Measuring ORP: MyronLMeters.com

Posted by 12 Apr, 2014

Tweet Ultrapen PT3 ORP tester Though the measurement of free chlorine concentration is often indicated for the disinfection of water and disinfectant byproduct control, there is a better way. Because free chlorine works through oxidation, ORP instrumentation can be used to monitor and control its effectiveness. ORP measures the actual oxidation power of the solution, […]



Ultrapen PT3 ORP tester Ultrapen PT3 ORP tester



Though the measurement of free chlorine concentration is often indicated for the disinfection of water and disinfectant byproduct control, there is a better way. Because free chlorine works through oxidation, ORP instrumentation can be used to monitor and control its effectiveness. ORP measures the actual oxidation power of the solution, specifically the strength and number of oxidation and reduction reactions in solution. This yields a clear picture of the efficacy of the chlorine present, regardless of the concentration or ratio of chlorine species in solution.
Measuring ORP directly reflects the sanitizing power of free chlorine or any other oxidizing or reducing chemicals. The measurement of ORP is precise, empirical and requires no user interpretation, making it ideal for water quality and industrial process control.
What is ORP?
ORP stands for Oxidation Reduction Potential, sometimes called REDOX. ORP is a differential measurement of the mV potentials built up when electrodes are exposed to solutions containing oxidants and reductants. ORP describes the net magnitude and direction of the flow of electrons between pairs of chemical species, called REDOX pairs.
In a REDOX pair, one chemical loses electrons while the other chemical gains electrons. The chemical in the REDOX exchange that acquires electrons is called the oxidant (HOCL, OCl-, ClO2, bromine, hydrogen peroxide, etc.). The chemical in the REDOX exchange that gives up electrons is called the reductant (Li, Mg2, Fe2+, Cr2, etc.). Oxidants acquire electrons through the process of reduction, i.e., they are reduced. Reductants lose their electrons through the process of oxidation, i.e., they become oxidized.
How is ORP measured?
ORP sensors are basically two electrochemical half-cells: A measurement electrode in contact with the solution being measured and a reference electrode in contact with a reservoir of highly concentrated salt solution.
When the solution being measured has a high concentration of oxidizers, it will accept more electrons than it loses so that the measurement electrode develops a higher electrical potential than the reference electrode. A voltmeter placed in line with the two electrodes will display this difference in potential between the two electrodes. Once the entire system reaches equilibrium, the resulting net potential difference represents the ORP. A positive reading indicates an oxidizing solution, and a negative reading indicates a reducing solution. The more positive or negative the value, the more powerful the oxidants or reductants, the greater their concentrations or both.
What does ORP measure?
ORP can be used to determine the efficacy of chemical disinfectants that work via the oxidation or reduction of the structures of microbial contaminants. For example, chlorine, an oxidant, will strip electrons from the negatively charged cell walls of some bacteria. Because ORP measures the total chemical activity of a solution, ORP measures the total efficacy all oxidizing and reducing disinfectants in solution: Hypochlorous acid, monochloramine, dichloramine, hypobromous acid, sodium hypochlorite, UV, ozone, peracetic acid, bromochlorodimethylhydantoin, etc.
ORP indicates the effectiveness of only those disinfectants that work through oxidation and reduction. ORP cannot be used to detect the presence of any one particular chemical or chemical species. Nor can it alone be used to determine the concentration of a known species of chemical in solution. This means that although ORP is the best way to know whether or not your sanitizer is working, it can’t tell you how much or what kind of sanitizer is working.
What factors affect ORP measurement?
While the accuracy of ORP sensors is relatively stable, which is why they do not require calibration, there are factors that affect their response time. Changes in temperature can affect response times by altering the kinetic rates of the reactions being measured, for example. Low temperatures reduce the kinetic rates and lengthen sensor response times.
The condition of the electrode will also alter response times by changing the “exchange current density” (the amount of electrons exchanged per unit area of exposed electrode). The lower the exchange current density, the more sluggish the sensor response. The typical measurement electrode is made from pure platinum (Pt) because it is a noble metal and, therefore, highly unreactive, i.e., the potential being measured is most likely due to the activity of the chemicals in the water and not reactions between the solution and the Pt itself. Even though Pt is a noble metal, it will form a thin oxide layer on the surface of the platinum when exposed to dissolved oxygen. This oxide layer facilitates the ORP measurement when it is very thin, one molecule thick, by attracting, or “adsorbing,” hydrolyzed oxidant or reductant molecules to the surface of the electrode.
Unfortunately, when the oxide layer becomes more than one molecule thick, the resulting lowered exchange current density offsets this benefit. Also, the adsorbed molecules cause a “memory effect.” If a sensor is placed in a less oxidizing solution after measuring a more oxidizing solution, it can take a very long time for the sensor to equilibrate to the new sample. Though the sensor response time is much slower, the final ORP reading will be the same.
ORP electrodes never require recalibration because there is no drift in zero point (as is the case with pH sensors). Any deviation from expected readings is most likely due to surface contamination of the electrodes or buildup of the oxide layer, both of which can easily be remedied by cleaning with a light abrasive, such as Softscrub®. Exposing the sensor to an “ORP conditioning solution” will help reduce the memory effect due to adsorption.
Can ORP be used as a surrogate parameter for free chlorine?
Yes. ORP measures the oxidizing power and, therefore, the actual residual sanitizing strength of the solution being tested. Simply counting how much chlorine is present is misleading because certain changes in water chemistry, such as pH or the addition of cyanuric acid, dramatically alter the oxidizing power of chlorine and, therefore, its efficacy, without changing how much chlorine is present.
When correlated with established disinfection control parameters, measurements and bacterial plate counts, this type of measurement gives a very accurate picture of the sanitizing activity. For this correlation to be valid, the water undergoing treatment must be characterized so that all chemical constituents are known. The pH and temperature values should be reported and held constant. ORP will report an empirical value or a hard number that indicates how active the sanitizer is. However, you have to make certain that microbial contamination is responding to the treatment. Once a correlation is established in a stable system, ORP is a very efficient and effective way to monitor microbial control.
ORP has long been used in bathing waters as the only means for automatic chemical dosing. In fact, the World Health Organization (WHO) suggests an ORP value of between 680-720 mV, depending on the sensor and the particular context, for safe bathing water. In the disinfection of drinking water, an ORP value of ~800 mV is required for oocyst inactivation.
For the purpose of pretreatment screening to detect chlorine levels prior to contact with chlorine-sensitive RO membranes, influent must first be screened to determine which chemicals besides chlorine are present that contribute to the ORP value. With these interferants characterized and pH and temperature held constant, ORP can be correlated to specific sanitizer concentrations, such as chlorine, in their known forms. Some manufacturers of RO membranes and other water quality treatment equipment will also specify an ORP tolerance value for prescreening and influent control. The same holds true of effluent screening.
Why ORP?
ORP is a faster, simpler empirical measurement than titration with DPD or other methods, and in many cases it gives the most accurate picture of the effect of all oxidizing and reducing chemicals in solution. No in-depth knowledge or training is required to obtain accurate repeatable results. User error is virtually eliminated because ORP readings require no subjective, visual interpretation, nor do they require calibration.
Using ORP disinfectant control can be automated because the measurement produces an electrical signal that can trigger switches when outside established control parameters. And ORP sensors are relatively low-maintenance. If you’re not using ORP to monitor and control chemical additions that work through REDOX, you should. You’ll save yourself time, hassle and money.
Myron L Meters is the premier internet retailer of accurate, reliable Myron L meters like the Ultrapen PT3, ORP pen tester.
Categories : Case Studies & Application Stories

Ultrapen PT3 ORP Pen Maintenance: MyronLMeters.com

Posted by 4 Apr, 2014

TweetMAINTENANCE Ultrapen PT3 ORP Pen I. Battery Replacement The PT3 display has a battery indicator that depicts the life remaining in the battery. When the indicator icon is at 3 bars, the battery is full. When the indicator icon falls to 1 bar, replace the battery with an N type battery.         […]

how to maintain and clean orp sensor for the ultrapen pt3

how to maintain and clean orp sensor for the ultrapen pt3

MAINTENANCE Ultrapen PT3 ORP Pen
I. Battery Replacement
The PT3 display has a battery indicator that depicts the life remaining in the battery. When the indicator icon is at 3 bars, the battery is full. When the indicator icon falls to 1 bar, replace the battery with an N type battery.

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1. In a CLEAN DRY environment unscrew the PT3 battery cap in a counter- clockwise motion.
2. Slide the cap and battery housing out of the PT3.
3. Remove the depleted battery out of its housing.
4. Insert a new battery into the battery housing oriented with the negative end touching the spring.
5. Align the groove along the battery housing with the guide bump inside the PT3 case and slide the battery housing back in.
6. Screw the battery cap back on to the PT3 in a clockwise direction. Do not over tighten.

II. Routine Maintenance

1. ALWAYS rinse the ORP sensor with clean water after each use.
2. ALWAYS replace the soaker cap with sponge filled with Sensor Storage
Solution to prevent the sensor from drying out after each use.
3. Cleaning the sensor: The Myron L Company recommends cleaning your sensor every two weeks, however this depends on application and frequency of use. Indications of a dirty sensor are slower and/or erroneous readings. Always recondition your sensor after cleaning.
To clean your sensor, select one of the following methods:
a. Basic Cleaning:
Using a solution made of dish soap mixed with water and a cotton swab, gently clean the inside of the sensor body and platinum electrode, rinse thoroughly with clean water, then recondition the sensor.
b. Moderate Cleaning:
Using a paste made of Comet® cleanser mixed with water and a cotton swab, gently clean the inside of the sensor body and platinum electrode, rinse thoroughly with clean water, then recondition the sensor. (If Comet® Cleanser is not available, use another mildly abrasive household cleanser).
c. Deep Cleaning:
Using ORP electrode cleaning paper and water, gently clean the platinum electrode, rinse thoroughly with clean water, then recondition the sensor.
4. Reconditioning the sensor: For greatest accuracy and speed of response, the Myron L Company recommends reconditioning the sensor after cleaning.
To recondition the sensor:
Rinse the sensor thoroughly with clean water, then allow it to soak in Storage Solution for a minimum of 1 hour (for best results allow the sensor to soak in Storage Solution overnight).
5. Do not drop, throw, or otherwise strike the PT3. This voids the warranty.
6. Do not store the PT3 in a location where the ambient temperatures exceed its specified Operating/Storage Temperature limits.

MyronLMeters.com is the premier internet retailer of the Ultrapen PT3 and other reliable Myron L meters. Save 10% on Myron L meters when you order online HERE.

Categories : Application Advice, Care and Maintenance, Product Updates, Technical Tips

Ultrapen PT3 ORP Pen Features: MyronLMeters.com

Posted by 4 Apr, 2014

Tweet                    The ULTRAPEN™ PT3 ORP Pen is designed to be extremely accurate, fast, and simple to use in diverse water quality applications. Advanced features include highly stable microprocessor-based circuitry; automatic temperature compensation from 15ºC to 30ºC while in calibration mode; user-intuitive design; and waterproof housing. A […]

 

DH-UP-PT3-2T

 

 

 

 

 

 

 

 

 

The ULTRAPEN™ PT3 ORP Pen is designed to be extremely accurate, fast, and simple to use in diverse water quality applications. Advanced features include highly stable microprocessor-based circuitry; automatic temperature compensation from 15ºC to 30ºC while in calibration mode; user-intuitive design; and waterproof housing. A true one-handed instrument, the PT3 is easy to calibrate and easy to use. To take a measurement, you simply push a button then dip the PT3 in solution. Results display in seconds.

FEATURES
1. Push Button — turns PT3 on; selects mode and unit of measurement preferences.
2. Battery Cap — provides access to battery for replacement.
3. Pocket Clip — holds PT3 to shirt pocket for secure storage.
4. Battery Indicator — indicates life remaining in battery.
5. Display — displays measurements, menu options, battery indicator, and
firmware revision (during power-up).
6. LED Indicator Light — indicates when to dip PT3 in solution, when measurement is in progress, and when to remove PT3 from solution.
7. ORP Sensor — measures oxidation-reduction potential or redox of solution.
8. Soaker Cap — contains a sponge soaked with Sensor Storage Solution to maintain sensor hydration. To remove, twist soaker cap while pulling off. To replace, fi soaker cap with storage solution just until sponge is covered. Squeeze and release tip of soaker cap so sponge will saturate with solution, then pour out any excess solution. Twist soaker cap while pushing back on.
CAUTION: Do NOT overfill the soaker cap as solution can squirt out while you are
pushing the cap back on.
9. Scoop — used to hold sample solution when dipping is not possible. To install, push scoop onto sensor while shifting side-to-side. To remove, pull scoop off while shifting side-to-side. Verify ORP sensor r
into PT3. If not, reinstall per ORP Sen page 5. To use, pour solution into scoop or hold scoop directly under a vertical stream to collect sample.
10. Holster — feed belt through strap in back of holster for hands-free portability.
11. Lanyard — attach through hole in top of pocket clip.
12. ORP Electrode Cleaning Paper — for deep cleaning the platinum electrode.

Technical Specs

ORP Range: -1000 mV to +1000 mV
ORP Accuracy: ± 10 mV
ORP Resolution: 1 mV ORP
Temperature Range: 0 – 71° C / 32 – 160° F
Temperature Accuracy: ± 0.1 ºC / ± 0.1 ºF
Temperature Resolution: 0.1ºC/0.1ºF
Time to Reading Stabilization: 10-45 seconds
Power Consumption: Active Mode 37 mA, Sleep Mode 2 μA
Temperature Compensation: Automatic In Calibration Mode From 15ºC to 30ºC
Physical Dimensions: 17,15 cm L x 1,59 cm D or 6.75 in. L x .625 in. D
Weight: 50,4 g / 1.78 oz. (without soaker cap and lanyard)
Case Material: Anodized Aircraft Aluminum with Protective Coating
Battery: One N type, Alkaline, 1.5V
Calibration Solutions: ORP80, ORP260, ORP470
Operating/Storage Temperature: 0 – 55ºC or 32 – 131ºF
Enclosure Ratings: IP67 and NEMA6
EN61236-1: 2006 – Annex A: 2008: Electrostatic discharge to the PT3 may cause it to spontaneously turn on. If this occurs, the PT3 will turn off.

* Temperature compensation in calibration mode: Temperature affects the reaction potentials for all chemicals differently. True ORP is the direct measurement of electron activity during an oxidation-reduction reaction, regardless of temperature. However, for maximum accuracy and ease of calibration, the Myron L Company has developed three calibration solutions with known dissolved species. We derived the temperature compensation (from 15ºC to 30ºC) for those solutions, and embedded automatic temperature compensation into the calibration function of your PT3. Note: To verify calibration while in measurement mode, you must manually correct for any variation in temperature. Example: @25ºC, ORP2602OZ calibration solution will read 260mV, however @ 20.0ºC ORP2602OZ will read 265mV.

MyronLMeters.com is the premier internet retailer of the Ultrapen PT3 and other reliable Myron L meters. Save 10% on Myron L meters when you order online HERE.

Categories : Product Updates

Conductivity Conversion to TDS in the Ultrameter: MyronLMeters.com

Posted by 1 Mar, 2014

TweetElectrical conductivity indicates solution concentration and ionization of the dissolved material. Since temperature greatly affects ionization, conductivity measurements are temperature dependent and are normally corrected to read what they would be at 25°C. A.           How It’s Done Once the effect of temperature is removed, the compensated conductivity is a function of the concentration (TDS). Temperature […]

Electrical conductivity indicates solution concentration and ionization of the dissolved material. Since temperature greatly affects ionization, conductivity measurements are temperature dependent and are normally corrected to read what they would be at 25°C.

A.           How It’s Done

Once the effect of temperature is removed, the compensated conductivity is a function of the concentration (TDS). Temperature compensation of the conductivity of a solution is performed automatically by the internal processor with data derived from chemical tables. Any dissolved salt at a known temperature has a known ratio of conductivity to concentration. Tables of conversion ratios referenced to 25°C have been published by chemists for decades.

B.           Solution Characteristics

Real world applications have to measure a wide range of materials and mixtures of electrolyte solutions. To address this problem, industrial users commonly use the characteristics of a standard material as a model for their solution, such as KCl, which is favored by chemists for its stability.

Users dealing with sea water, etc., use NaCl as the model for their concentration calculations. Users dealing with freshwater work with mixtures including sulfates, carbonates and chlorides, the three predominant components (anions) in freshwater that Myron L calls “Natural Water”. These are modeled in a mixture called “442™” which Myron L uses as a calibration standard, as it does standard KCl and NaCl solutions.

The Ultrameter II contains algorithms for these 3 most commonly referenced compounds. The solution type in use is displayed on the left. Besides KCl, NaCl, and 442, there is the User choice. The benefit of the User solution type is that one may enter the temperature compensation and TDS ratio by hand, greatly increasing accuracy of readings for a specific solution. That value remains a constant for all measurements and should be reset for different dilutions or temperatures.

C.           When does it make a lot of difference?

First, the accuracy of temperature compensation to 25°C determines the accuracy of any TDS conversion. Assume we have industrial process water to be pretreated by RO. Assume it is 45°C and reads 1500 µS uncompensated.

1.         If NaCl compensation is used, an instrument would report 1035 µS compensated, which corresponds to 510 ppm NaCl.

2.         If 442 compensation is used, an instrument would report 1024 µS compensated, which corresponds to 713 ppm 442.

The difference in values is 40%.

In spite of such large error, some users will continue to take data in the NaCl mode because their previous data gathering and process monitoring was done with an older NaCl referenced device.

Selecting the correct Solution Type on the Ultrameter II will allow the user to attain true TDS readings that correspond to evaporated weight.

If none of the 3 standard solutions apply, the User mode must be used.

TEMPERATURE COMPENSATION (Tempco) and TDS DERIVATION

The Ultrameter II contains internal algorithms for characteristics of the 3 most commonly referenced compounds. The solution type in use is displayed on the left. Besides KCl, NaCl, and 442, there is the User choice. The benefit of User mode is that one may enter the tempco and TDS conversion values of a unique solution via the keypad.

A. Conductivity Characteristics
When taking conductivity measurements, the Solution Selection determines the characteristic assumed as the instrument reports what a measured conductivity would be if it were at 25°C. The characteristic is represented by the tempco, expressed in %/°C. If a solution of 100 µS at 25°C increases to 122 µS at 35°C, then a 22% increase has occurred over this change of 10°C. The solution is then said to have a tempco of 2.2 %/°C. Tempco always varies among solutions because it is dependent on their individual ionization activity, temperature and concentration. This is why the Ultrameter II features mathematically generated models for known salt characteristics that also vary with concentration and temperature.

B. Finding the Tempco of an Unknown Solution

One may need to measure compensated conductivity of some solution unlike any of the 3 standard salts. In order to enter a custom fixed tempco for a limited measurement range, enter a specific value through the User function. The tempco can be determined by 2 different methods:

1. Heat or cool a sample of the solution to 25°C, and measure its conductivity. Heat or cool the solution to a typical temperature where it is normally measured. After selecting User function, set the tempco to 0 %/°C as in Disabling Temperature Compensation, pg. 15 (No compensation). Measure the new conductivity and the new temperature. Divide the % decrease or increase by the 25°C value. Divide that difference by the temperature difference.

2. Heat or cool a sample of the solution to 25°C, and measure its conductivity. Change the temperature to a typical measuring temperature. Set the tempco to an expected value as in User Programmable Temperature Compensation, pg. 15. See if the compensated value is the same as the 25°C value. If not, raise or lower the tempco and measure again until the 25°C value is read.

C. Finding the TDS Ratio of an Unknown Solution

Once the effect of temperature is removed, the compensated conductivity is a function of the concentration (TDS).

There is a ratio of TDS to compensated conductivity for any solution, which varies with concentration. The ratio is set during calibration in User mode as in User Programmable Conductivity to TDS Ratio, pg. 16.
A truly unknown solution has to have its TDS determined by evaporation and weighing. Then the solution whose TDS is now known can be measured for conductivity and the ratio calculated. Next time the same solution is to be measured, the ratio is known.

ph and ORP (6PFCE)

1. pH as an Indicator (6PFCE)

pH is the measurement of Acidity or Alkalinity of an aqueous solution. It is also stated as the Hydrogen Ion activity of a solution. pH measures the effective, not the total, acidity of a solution.
A 4% solution of acetic acid (pH 4, vinegar) can be quite palatable, but a 4% solution of sulfuric acid (pH 0) is a violent poison. pH provides the needed quantitative information by expressing the degree of activity of an acid or base. In a solution of one known component, pH will indicate concentration indirectly. However, very dilute solutions may be very slow reading, just because the very few ions take time to accumulate.

2. pH Units (6PFCE)

The acidity or alkalinity of a solution is a measurement of the relative availabilities of hydrogen (H+) and hydroxide (OH-) ions. An increase in (H+) ions increases acidity, while an increase in (OH-) ions increases alkalinity. The total concentration of ions is fixed as a characteristic of water, and balance would be 10-7 mol/liter (H+) and (OH-) ions in a neutral solution (where pH sensors give 0 voltage).
pH is defined as the negative logarithm of hydrogen ion concentration. Where (H+) concentration falls below 10-7, solutions are less acidic than neutral, and therefore are alkaline. A concentration of 10-9 mol/liter of (H+) would have 100 times less (H+) ions than (OH-) ions and be called an alkaline solution of pH 9.

3. The pH Sensor (6PFCE)

The active part of the pH sensor is a thin glass surface that is selectively receptive to hydrogen ions. Available hydrogen ions in a solution will accumulate on this surface and a charge will build up across the glass interface. The voltage can be measured with a very high impedance voltmeter circuit; the dilemma is how to connect the voltmeter to solution on each side.
The glass surface encloses a captured solution of potassium chloride holding an electrode of silver wire coated with silver chloride. This is the most inert connection possible from a metal to an electrolyte. It can
still produce an offset voltage, but using the same materials to connect to the solution on the other side of the membrane causes the 2 equal offsets to cancel.
The problem is, on the other side of the membrane is an unknown test solution, not potassium chloride. The outside electrode, also called the Reference Junction, is of the same construction with a porous plug in place of a glass barrier to allow the junction fluid to contact the test solution without significant migration of liquids through the plug material. Figure 33 shows a typical 2 component pair. Migration does occur, and this limits the lifetime of a pH junction from depletion of solution inside the reference junction or from contamination. The junction may be damaged if dried out because insoluble crystals may form in a layer, obstructing contact with test solutions.

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Figure 33

 

Glass Surface

H+ ions

Junction plug
Platinum button

 

KCl solution

 

 

Glass

 

 

Electrode wires

 

 

 

4. The Myron L Integral pH Sensor (6PFCE)

The sensor in the Ultrameter II (see Figure 34) is a single construction in an easily replaceable package. The sensor body holds an oversize solution supply for long life. The reference junction “wick” is porous to provide a very stable, low permeable interface, and is located under the glass pH sensing electrode. This construction combines all the best features of any pH sensor known.

5. Sources of Error (6PFCE)

The most common sensor problem will be a clogged junction because a sensor was allowed to dry out. The symptom is a drift in the “zero” setting at 7 pH. This is why the Ultrameter II 6PFCE does not allow more than 1 pH unit of offset during calibration. At that point the junction is unreliable.

b. Sensitivity Problems

Sensitivity is the receptiveness of the glass surface. A film on the surface can diminish sensitivity and cause a long response time.

c. Temperature Compensation

pH sensor glass changes its sensitivity slightly with temperature, so the further from pH 7 one is, the more effect will be seen. A pH of 11 at 40°C would be off by 0.2 units. The Ultrameter II 6PFCE senses the sensor well temperature and compensates the reading.

B. ORP/Oxidation-Reduction Potential/REDOX (6PFCE)

1. ORP as an Indicator (6PFCE)

ORP is the measurement of the ratio of oxidizing activity to reducing activity in a solution. It is the potential of a solution to give up electrons (oxidize other things) or gain electrons (reduce).
Like acidity and alkalinity, the increase of one is at the expense of the other, so a single voltage is called the Oxidation-Reduction Potential, with a positive voltage showing, a solution wants to steal electrons (oxidizing agent). For instance, chlorinated water will show a positive ORP value.

2. ORP Units (6PFCE)

ORP is measured in millivolts, with no correction for solution temperature. Like pH, it is not a measurement of concentration directly, but of activity level. In a solution of only one active component, ORP indicates concentration. Also, as with pH, a very dilute solution will take time to accumulate a readable charge.

3. The ORP Sensor (6PFCE)
An ORP sensor uses a small platinum surface to accumulate charge without reacting chemically. That charge is measured relative to the solution, so the solution “ground” voltage comes from a reference junction – same as the pH sensor uses.

4. The Myron L ORP Sensor (6PFCE)

Figure 34, pg. 45, shows the platinum button in a glass sleeve. The same reference is used for both the pH and the ORP sensors. Both pH and ORP will indicate 0 for a neutral solution. Calibration at zero compensates for error in the reference junction. A zero calibration solution for ORP is not practical, so the Ultrameter II 6PFCE uses the offset value determined during calibration to 7 in pH calibration (pH 7 = 0 mV). Sensitivity of the ORP surface is fixed, so there is no gain adjustment either.

5. Sources of Error (6PFCE)

The basics are presented in pH and ORP, pg. 44, because sources of error are much the same as for pH. The junction side is the same, and though the platinum surface will not break like the glass pH surface, its protective glass sleeve can be broken. A surface film will slow the response time and diminish sensitivity. It can be cleaned off with detergent or acid, as with the pH glass.

C. Free Chlorine

1. Free Chlorine as an Indicator of Sanitizing Strength Chlorine, which kills bacteria by way of its power as an oxidizing agent, is the most popular germicide used in water treatment. Chlorine is not only used as a primary disinfectant, but also to establish a sufficient residual level of Free Available Chlorine (FAC) for ongoing disinfection.

FAC is the chlorine that remains after a certain amount is consumed by killing bacteria or reacting with other organic (ammonia, fecal matter) or inorganic (metals, dissolved CO2, Carbonates, etc) chemicals in solution. Measuring the amount of residual free chlorine in treated water is a well accepted method for determining its effectiveness in microbial control.

The Myron L  FCE method for measuring residual disinfecting power is based on ORP, the specific chemical attribute of chlorine (and other oxidizing germicides) that kills bacteria and microbes.

2. FCE Free Chlorine Units

The 6PIIFCE is the first handheld device to detect free chlorine directly, by measuring ORP. The ORP value is converted to a concentration reading (ppm) using a conversion table developed by Myron L Company through a series of experiments that precisely controlled chlorine levels and excluded interferants.

Other test methods typically rely on the user visually or digitally interpreting a color change resulting from an added reagent-dye. The reagent used radically alters the sample’s pH and converts the various chlorine species present into a single, easily measured species. This ignores the effect of changing pH on free chlorine effectiveness and disregards the fact that some chlorine species are better or worse sanitizers than others.

The Myron L 6PIIFCE avoids these pitfalls. The chemistry of the test sample is left unchanged from the source water. It accounts for the effect of pH on chlorine effectiveness by including pH in its calculation. For these reasons, the Ultrameter II’s FCE feature provides the best reading-to-reading picture of the rise and fall in sanitizing effectivity of free available chlorine.

The 6PIIFCE also avoids a common undesirable characteristic of other ORP-based methods by including a unique Predictive ORP value in its FCE calculation. This feature, based on a proprietary model for ORP sensor behavior, calculates a final stabilized ORP value in 1 to 2 minutes rather than the 10 to 15 minutes or more that is typically required for an ORP measurement.

The Myron L Ultrameter II 6PFCe is available at MyronLMeters.com, the premier internet retailer of Myron L products. Save 10% on the Myron L Ultrameter II6 PFCe when you order online here: http://www.myronlmeters.com/Myron-L-6P-Ultrameter-II-Multiparameter-Meter-p/dh-umii-6pii.htm

 

Categories : Application Advice, Technical Tips

The Ultrameter II™ in Disaster Response: MyronLMeters.com

Posted by 29 Oct, 2013

TweetWhen disaster strikes, people are scared and disorganized. They need resources — safe water and proper sanitation — that aren’t easy to come by in the aftermath. Without the help of humanitarian organizations to provide assistance, large populations of survivors are subject to epidemics of cholera, diarrhea, meningitis, and other diseases as they struggle to […]

Ultrameter II 6P

Ultrameter II 6P

When disaster strikes, people are scared and disorganized. They need resources — safe water and proper sanitation — that aren’t easy to come by in the aftermath. Without the help of humanitarian organizations to provide assistance, large populations of survivors are subject to epidemics of cholera, diarrhea, meningitis, and other diseases as they struggle to meet these basic needs.

Qualified Help
Dr. Roddy Tempest, a leading designer and manufacturer of water purification systems has headed the efforts of public and private aid organizations, such as the United Nations and AmeriCares, in responding to people in crisis all over the world for over 15 years.

Dr. Tempest contributed his expertise and experience in such situ- ations as the aftermath of Hurricane Andrew in 1992, the Kosovar refugee crisis in the Balkans, the devastating earthquakes in Tur- key and the flood and mudslides that ravaged the coastal states of Venezuela in 1999. He has assisted in disaster relief efforts in Japan, Africa, Central America, and Taiwan, as well.

So when AmeriCares launched its water purification program for the inhabitants of Sri Lanka following the devastation of the tsunami on December 26, 2004, it turned to Dr. Tempest.

For this heroic effort, Dr. Tempest used two Ultrameter II 6P portable, handheld water testing instruments. Dr Tempest said the instruments gave him “a good, quick first-brush assessment of the possible water sources.”

The Ultrameter II reported and recorded instant precise measurements of Conductivity, Resistivity, TDS, ORP (REDOX), pH, and Temperature. But creating a livable situation for hundreds of thousands of displaced survivors wasn’t as easy as testing the water.

Water Doctor to the Rescue
From his offices in the United States, Dr. Tempest responded to the call for help by first reviewing satellite maps that showed the location of potential water sources in relation to groups of survivors, or Internally Displaced Persons (IDPs). He assessed the total situation of the potential water sources, trying at a glance to deter- mine possible contamination by flooding or infiltration of seawater. Upon his arrival in Sri Lanka, Dr. Tempest worked 24 hours a day to determine a suitable survival supply of water for the IDPs. As indicated in the World Health Organization’s Environmental Health in Emergencies and Disasters, the required water per person per day is 15 liters / 3.963 gallons.

Faced with this daunting task, Dr. Tempest surveyed the land via helicopter and fixed wing aircraft to record the extent of the damage, the location of IDPs, and the viability of potential water sources. Some of the photographs reveal the mammoth challenge he had ahead of him. Debris lay everywhere, indicating the likelihood of surface water and well contamination. Filtration was a must.

Dr. Tempest then combined satellite imagery, the photographs and sketches of water sources from his survey and a list of supplies to determine which water sources would be targeted for testing.

Following World Health Organization guidelines, Dr. Tempest considered as many potential water sources as possible, not just the most obvious ones. These included surface and groundwater near the groups of IDPs and tankered or bottled water brought in from a distance – though this would not be suitable for the long- term supply. The preferred source would have been groundwater, especially for the long-term.

Ultrameter II in Action
Dr. Tempest used the Ultrameter II 6P to screen these sources for their potential disinfection and filtering.
First, Dr. Tempest considered whether or not potential water sources could be protected from pollution and secured. Any potential source water had to be filterable and sanitizable. If the water was brackish, it would require a certain treatment method. If it was high in turbidity, then it would require another. If the pH needed adjusting, then yet another. If the source water was not easily treatable, then the source had to be discarded as an option and a better alternative found.

The Ultrameter II provided Dr. Tempest with fast, reliable, accurate initial information on whether or not to pursue further testing and treatment of a potential source. Dr. Tempest used a multiparameter approach and tested for Total Dissolved Solids (TDS), pH, ORP (REDOX), and temperature (recorded with every reading taken.) He also tested for turbidity and bacteria using other instrumentation.

Initially, Dr. Tempest used a measurement of the mineral salt concentration using TDS calibrated to a sodium chloride solution and TDS calibrated to a natural water standard.

Right away Dr. Tempest knew whether or not the water was too saline or saturated to be filtered  economically. If the TDS is too high, filtration systems that work by reverse osmosis can be overwhelmingly expensive to operate in a disaster area, especially considering electrical costs alone. At the very least, the systems become less efficient as the TDS increases and a burden in operation and maintenance costs. This is critical for the short-term disaster response, where Dr. Tempest has to get as much safe water to IDPs in as short amount of time as possible.

High TDS can also indicate an unacceptable level of specifically known inorganic contaminants caused by industrial pollution.
And though it is not a health consideration, high TDS water often has an unpleasant taste that deters people from using it. People may try to return to old wells or other sources of previously safe drinking water that have been contaminated in the disaster. The old source may be more trusted than one that tastes “polluted.” So even though TDS is a secondary water quality standard, it can profoundly impact whether or not the new source is acceptable.

Dr. Tempest also took instant electronic pH readings using the Ultrameter II. The pH directly affects the potential to disinfect the water. pH levels beyond 8 will require substantial increases in the amount of disinfectant required or the length of time the water must be disinfected before safe consumption. And at a pH beyond 9, a residual disinfectant is extremely difficult to maintain.

pH is also critical in the long-term disaster recovery planning. pH that is too low or too high affects water balance, as well, and can contribute to either corrosion or scaling of filtration and disinfection system components and plumbing. An electronic meter is the best choice in this application as compared to colored strips or solutions or other colorimetric methods that do not produce the accuracy required to consistently and correctly balance water and maintain proper disinfection levels. The more precisely the pH is maintained, the less costly safe water production is.

Dr. Tempest also took quick ORP (REDOX) measurements using the Ultrameter II. ORP (REDOX) is the oxidation reduction potential of the water and indicates the state of the water for gaining or losing electrons. Unlike pH, which measures the water’s ability to donate or receive hydrogen ions, ORP (REDOX) values reflect the presence of all oxidizing and reducing agents — not just acids and bases. Initially, the ORP (REDOX) value gave Dr. Tempest a rough idea of the organic load in the water. A reading of 650 mV or greater indicated good water quality that could effectively be sanitized by a minimal amount of free chlorine. A value like 250 mV indicated that the organic contaminants would significantly increase chlorine demand and thereby significantly increase operation and management costs.

ORP (REDOX) is not only a good first indicator about the viability of a water source, but it also is the best way of measuring the disinfectant present in the water after treatment has begun.

Putting It All Together
Using all of the results from these parameters and based on his knowledge of the location of IDPs in relation to potential water sources, Dr. Tempest decided which source would satisfy the needs of each specific location of groups of IDPs. Where possible, water treatment technology would be designed around the quality of the source waters tested where IDPs had gathered, since it was not practical to re-locate large groups of people to distant water sources. Unfortunately, in the case of the Tsunami in Sri Lanka, oftentimes the water closest to IDPs could not be filtered and relocation was necessary.

Dr. Tempest found after his first quick assessment of potential water sources that it was not practical to supply the IDPs in parts of the Batticoloa and Ampara Districts along the eastern coast, because the source water was too saline from seawater intrusion. With limited electricity, this
made the use of reverse osmosis or desalination equipment impractical.

He ended up settling on sites that were more inland, using source waters from man-made reservoirs. IDPs were then settled inland near the cleaner water source.

However, the water in the man-made reservoirs was heavily contaminated with toxic blue-green algae.

Dr. Tempest chose microfiltration and ultrafiltration water treatment systems in the eastern district locations, taking algae-infested water over the salt-saturated, so that treatment and operation costs would be significantly less. Dr. Tempest designed, built and commissioned 4 large transportable water treatment systems, each capable of producing over 500,000 liters/day.

Plans then continued to follow through with long-term water treatment using the Tempest Environmental Systems equipment for the Sri Lankan Ministry of Urban Development and Water Supply and their National Water Supply & Drain- age Board (NWSDB). The NWSDB has 14 Ultrameter II 6Ps in current use in Sri Lanka, which are providing continuing confidence checks to ensure system equipment remains up and running properly.

The Ultrameter II 6P is an excellent multiparameter water quality meter used by thousands of water treatment professionals. The instrument can test for pH, total dissolved solids, conductivity, resistivity, oxidation reduction potential, temperature, and has the capability of testing for free chlorine. This meter handles the job of SIX single parameter testers using one single water sample. Save 10% on the Ultrameter II 6P at MyronLMeters.com.

 

 

Categories : Case Studies & Application Stories

ORP Applications – MyronLMeters.com

Posted by 26 Aug, 2013

TweetWHAT IS ORP? Oxidation Reduction Potential or Redox is the activity or strength of oxidizers and reducers in relation to their concentration. Oxidizers accept electrons, reducers lose electrons. Examples of oxidizers are: chlorine, hydrogen peroxide, bromine, ozone, and chlorine dioxide. Examples of reducers are sodium sulfite, sodium bisulfate and hydrogen sulfide. Like acidity and alkalinity, […]

WHAT IS ORP?

Oxidation Reduction Potential or Redox is the activity or strength of oxidizers and reducers in relation to their concentration. Oxidizers accept electrons, reducers lose electrons. Examples of oxidizers are: chlorine, hydrogen peroxide, bromine, ozone, and chlorine dioxide. Examples of reducers are sodium sulfite, sodium bisulfate and hydrogen sulfide. Like acidity and alkalinity, the increase of one is at the expense of the other.

A single voltage is called the Oxidation-Reduction Potential, where a positive voltage shows a solution attracting electrons (oxidizing agent). For instance, chlorinated water will show a positive ORP value whereas sodium sulfite (a reducing agent) loses electrons and will show a negative ORP value.

ORP is measured in millivolts (mV), with no correction for solution temperature. Like pH, it is not a measurement of concentration directly, but of activity level. In a solution of only one active component, ORP indicates concentration. As with pH, a very dilute solution will take time to accumulate a measurable charge.

An ORP sensor uses a small platinum surface to accumulate charge without reacting chemically. That charge is measured relative to the solution, so the solution “ground” voltage comes from the reference junction – the same type used by a pH sensor.

HISTORY OF ORP

ORP electrodes were first studied at Harvard University in 1936. These studies showed a strong correlation of ORP and bacterial activity. These tests were confirmed by studies on drinking water and swimming pools in other areas of the world. In 1971 ORP (700 mV) was adopted by the World Health Organization (WHO) as a standard for drinking water. In 1982 the German Standards Agency adopted the ORP (750 mV) for public pools and in 1988 the National Swimming Pool Institute adopted ORP (650 mV) for public spas.

WHERE IS ORP USED?
As you can tell by the previous paragraphs, ORP is used for drinking water, swimming pools and spas. However, ORP is also used for cooling tower disinfection, groundwater remediation, bleaching, cyanide destruction, chrome reductions, metal etching, fruit and vegetable disinfection and dechlorination.

In test after test on poliovirus, E. coli, and other organisms, a direct correlation between ORP and the rate of inactivation was determined. It is, therefore, possible to select an individual ORP value, expressed in millivolts, at which a predictable level of disinfection will be achieved and sustained regardless of variations in either oxidant demand or oxidant concentration. Thus, individual ORP targets, expressed in millivolts, can be determined for each application, which will result in completely reliable disinfection of pathogens, oxidation of organics, etc. Any level of oxidation for any purpose can be related to a single ORP number which, if maintained, will provide utterly consistent results at the lowest possible dosage.

WHY USE ORP?

ORP is a convenient measure of the oxidizer’s or reducer’s ability to perform a chemical task. ORP is not only valid over a wide pH range, but it is also a rugged electrochemical test, which can easily be accomplished using in-line and handheld instrumentation. It is by far a more consistent and reliable measurement than say chlorine alone.

LIMITATIONS FOR ORP
As with all testing, ORP has certain limitations. The speed of response is directly related to the exchange current density which is derived from concentration, the oxidation reduction system, and the electrode. If the ORP of a sample is similar to the ORP of the electrode, the speed will be diminished.

Carryover is also a possible problem when checking strong oxidizers or reducers, and rinsing well will help greatly.

Although a better indicator of bactericidal activity, ORP cannot be used as a direct indicator of the residual of an oxidizer due to the effect of pH and temperature on the reading. ORP can be correlated to a system by checking the oxidizer or reducer in a steady state system with a wet test, and measuring pH. If the system stays within the confines of this steady state parameter (usually maintained by in- line or continuous control), a good correlation can be made. The best recommendation for ORP is to use wet tests, and over three test periods correlate the ORP values to those test parameters.

FREE CHLORINE CONVERSION USING ORP

The most ubiquitous and cost-effective sanitizing agent used in disinfection systems is chlorine. When chlorine is used as the sanitizer, free chlorine measurements are required to ensure residual levels high enough for ongoing bactericidal activity. Myron L meters accurately convert ORP measurements to free chlorine based on the understanding of the concentrations of the forms of free chlorine at a given pH and temperature. The conversion is accurate when chlorine is the only oxidizing/reducing agent in solution and pH is stable between 5 and 9. This pH range fits most applications because pH is usually maintained such that the most effective form of free chlorine, hypochlorous acid, exists in the greatest concentration with respect to other variables such as human tolerance.

MYRON L METERS

Myron L offers a variety of handheld instruments and in-line Monitor/controllers that may be used to measure, monitor and/or control ORP. The latest is the Ultrapen PT3, ORP/Redox and Temperature Pen. The Ultrameter III™ 9PTKA, Ultrameter II™ 6PFCE, PoolPro™ PS6FCE and PS9TK, and D-6 Digital Dialysate Meter™ are multi-parameter handheld instruments with ORP and FCE free chlorine measuring capabilities. These instruments also have the capability to measure conductivity, TDS, resistivity, pH, mineral/salt concentration and temperature, making them the preferred instruments for all water treatment professionals. The 720 Series II Monitor/controllers are an excellent choice for continuous in-line measurements.

For additional information, visit us at MyronLMeters.com.

Categories : Case Studies & Application Stories, Science and Industry Updates

The Ultrapen PT-3: MyronLMeters.com

Posted by 12 Jun, 2013

Tweet Myron l Meters Ultrapen PT-3 from Myron L Meters

Myron l Meters Ultrapen PT-3 from Myron L Meters
Categories : Product Updates

Application Bulletin: POOL & SPA Water – MyronLMeters.com

Posted by 31 Jan, 2013

Tweet                 Anyone responsible for operating and maintaining a swimming pool or spa has to test, monitor, and control complex, interdependent chemical factors that affect the quality of water. Additionally, aquatic facilities operators must be familiar with all laws, regulations, and guidelines governing what these parameters should be. […]

DH-PS9-TK-2T

 

 

 

 

 

 

 

 

Anyone responsible for operating and maintaining a swimming pool or spa has to test, monitor, and control complex, interdependent chemical factors that affect the quality of water. Additionally, aquatic facilities operators must be familiar with all laws, regulations, and guidelines governing what these parameters should be.

Why? Because the worst breeding ground for any kind of microorganism is a warm (enough) stagnant pool of water. People plus stagnant water equals morbid illness. That’s why pools have to be circulated, filtered, and sanitized –  with any number of chemicals or methods, but most frequently with chlorine compounds. However, adding chemicals that kill the bad microorganisms can also make the water uncomfortable, and in some cases unsafe, for swimmers. Additionally, if all the chemical factors of the water are not controlled, the very structures and equipment that hold the water and keep it clean are ruined.

So the pool professional must perform a delicate balancing act with all the factors that affect both the health and comfort of bathers and the equipment and structures that support this. Both water balance – or mineral saturation control – and sanitizer levels must constantly be maintained. This is achieved by measuring pertinent water quality factors and adding chemicals or water to keep the factors within acceptable parameters.

 WATER BALANCE

Water is constantly changing. Anything and everything directly and indirectly affects the relationship of its chemical parameters to each other: sunlight, wind, rain, oil, dirt, cosmetics, other bodily wastes, and any chemicals you add to it. Balanced water not only keeps swimmers comfortable, but also protects the pool shell, plumbing, and all other related equipment from damage by etching or build-up and stains.

The pool professional is already well acquainted with pH, Total Alkalinity (TA), and Calcium Hardness (CH); along with Total Dissolved Solids (TDS) and Temperature, these are the factors that influence water balance. Water that is in balance is neither aggressive nor oversaturated. Aggressive water lacks sufficient calcium to saturate the water, so it is hungry for more. It will eat anything it comes into contact with to fill its need, including the walls of your pool or spa or the equipment it touches. Over-saturated water cannot hold any more minerals, so dissolved minerals come out of solution and form scale on pool and equipment surfaces.

The pH of pool water is critical to the effectiveness of the sanitizer as well as the water balance. pH is determined by the concentration of Hydrogen ions in a specific volume of water. It is measured on a scale of 0-14, 0-7 being acidic and 7-14 being basic.

You must maintain the pH of the water at a level that assures the sanitizer works effectively and at the same time protects the pool shell and equipment from corrosion or scaling and the bathers from discomfort or irritation. If the pH is too high, the water is out of balance, and the sanitizer’s ability to work decreases. More and more sanitizer is then needed to maintain the proper level to kill off germs. Additionally, pH profoundly affects what and how much chemical must be added to control the balance. A pH of between 7.2 – 7.6 is desirable in most cases.*

As one of the most important pool water balance and sanitation factors, pH should be checked hourly in most commercial pools.* Even if you have an automatic chemical monitor/controller on your system, you need to double- check its readings with an independent pH test. With salt- water pools, pH level goes up fast, so you need to check it more often. Tests are available that require reagents and subjective evaluation of color depth and hue to judge their pH. But different users interpret these tests differently, and results can vary wildly. The PooLPRo and ULTRAPEN PT2 give instant lab-accurate, precise, easy-to-use, objective pH measurements, invaluable in correctly determining what and how much chemical to add to maintain water balance and effective sanitizer residuals.

Total Alkalinity (TA) is the sum of all the alkaline minerals in the water, primarily in bicarbonate form in swimming pools, but also as sodium, calcium, magnesium, and potassium carbonates and hydroxides, and affects pH directly through buffering. The greater the Total Alkalinity, the more stable the pH. In general, TA should be maintained at 80 – 120 parts per million (ppm) for concrete pools to keep the pH stable.* Maintaining a low TA not only causes pH bounce, but also corrosion and staining of pool walls and eye irritation. Maintaining a high TA causes overstabilization of the water, creating high acid demands, formation of bicarbonate scale, and may result in the formation of white carbonate particles (suspended solids), which clouds the water. Reducing TA requires huge amounts of effort. So the best solution to TA problems is prevention through close monitoring and controlling. The PoolPro PS9 Titration Kit features an in-cell conductometric titration for determining alkalinity.

 Calcium Hardness (CH) is the other water balance parameter pool professionals are most familiar with. CH represents the calcium content of the water and is measured in parts per million. Low CH combined with a low pH and low TA significantly increases corrosivity of water. Under these conditions, the solubility of calcium carbonate also increases. Because calcium carbonate is a major component of both plaster and marcite, these types of pool finishes will deteriorate quickly. Low CH also leads to corrosion of metal components in the pool plant, particularly in heat exchangers. Calcium carbonate usually provides a protective film on the surface of copper heat exchangers and heat sinks, but does not adversely affect the heating process. Without this protective layer, heat exchangers and associated parts can be destroyed prematurely. At the other extreme, high CH can lead to the precipitation of calcium carbonate from solution, resulting in cloudy water, the staining of structures and scaling of equipment. The recommended range for most pools is 200 – 400 ppm.* Calcium hardness should be tested at least monthly. The PoolPro  PS9 Titration Kit features an in-cell conductometric titration for determining hardness.

Total Dissolved Solids (TDS) is the sum of all solids dissolved in water. If all the water in a swimming pool was allowed to evaporate, TDS would be what was left on the bottom of the pool – like the white deposits left in a boiling pot after all the water has evaporated. Some of this dissolved material includes hardness, alkalinity, cyanuric acid, chlorides, bromides, and algaecides. TDS also includes bather wastes, such as perspiration, urine, and others. TDS is often confused with Total Suspended Solids (TSS). But TDS has no bearing on the turbidity, or cloudiness, of the water, as all the solids are truly in solution. It is TSS, or undissolved, suspended solids, present in or that precipitate out of the water that make the water cloudy.

High TDS levels do affect chlorine efficiency, algae growth, and aggressive water, but only minimally. TDS levels have the greatest bearing on bather comfort and water taste – a critical concern for commercial pool operators. At levels of over 5,000 ppm, people can taste it. At over 10,000 ppm bather towels are scratchy and mineral salts accumulate around the pool and equipment. Still some seawater pools comfortably operate with TDS levels of 32,000 ppm or more.

As methods of sanitization have changed, high TDS levels have become more and more of a problem. The best course of action is to monitor and control TDS by measuring levels and periodically draining and replacing some of your mature water with new, lower TDS tap water. This is a better option than waiting until you must drain and refill your pool, which is not allowed in some areas where water conservation is required by law. However, you can also decrease TDS with desalinization equipment as long as you compensate with Calcium Hardness. (Do not adjust water balance by moving pH beyond 7.8.)*

Regardless, you do need to measure and compensate for TDS to get the most precise saturation index and adjust your pH and Calcium Hardness levels accordingly. It is generally recommended that you adjust for TDS levels by subtracting one tenth of a saturation index unit (.1) for every 1,000 ppm TDS over 1,000 to keep your water properly balanced. When TDS levels exceed 5,000 ppm, it is recommended that you subtract half of a tenth, or one twentieth of unit (.05) per 1,000 ppm.* And as the TDS approaches that of seawater, the effect is negligible.

Hot tubs and spas have a more significant problem with TDS levels than pools. Because the bather load is relatively higher, more chemicals are added for superchlorination and sudsing along with a higher concentration of bather wastes. The increased electrical conductance that high TDS water promotes can also result in electrolysis or galvanic corrosion. Every hot water pool operator should consider a TDS analyzer as a standard piece of equipment.

A TDS analyzer is required to balance the water of any pool or spa in the most precise way. PoolPro, PoolMeter and ULTRAPEN PT1 instantly display accurate TDS levels giving you the information you need to take corrective action before TDS gets out of hand.

Temperature is the last and least significant factor in maintaining water balance. As temperature increases, the water balance tends to become more basic and scale- producing. Calcium carbonate becomes less soluble, causing it to precipitate out of solution. As temperature drops, water becomes more corrosive.

 In addition to helping determine water balance, temperature also affects bather comfort, evaporation, chlorination, and algae growth (warmer temperatures encourage growth). Myron L’s PooLPRo also precisely measures temperature to one tenth of a degree at the same time any other parameter is measured.

In the pool and spa industry water balance is calculated using the Langelier Saturation Index (LSI) formula:

SI = (pH + TF + CF + AF ) – 12.1

Where:

PH = pH value

TF = 0.0117 x Temperature value – 0.4116 CF = 0.4341 x ln(Hardness value) – 0.3926 AF = 0.4341 x ln(Alkalinity value) – 0.0074

The following is a general industry guideline for interpreting LSI values:

•   An index between -0.5 and +0.5 is acceptable pool water.

  • An index of more than +0.5 is scale-forming.
  • An index below -0.5 is corrosive.

pH, Total Alkalinity, and Calcium Hardness are the largest contributors to water balance. Pool water will often be balanced if these factors are kept within the recommended ranges.

The PoolPro PS9 Titration Kit features an LSI function that steps you through alkalinity & hardness titrations and pH & temperature measurements to quickly and accurately determine LSI. An LSI calculator allows you to manipulate pH, alkalinity, hardness and temperature values in the equation to determine water balance adjustments on the spot.

SANITATION

The most immediate concern of anyone monitoring and maintaining a pool is the effectiveness of the sanitizer – the germ-killer. There are many types of sanitizers, the most common being chlorine in swimming pools and bromine in hot tubs and spas. The effectiveness of the sanitizer is directly related to the pH and, to a lesser degree, the other factors influencing water balance.

To have true chemical control, you need to monitor both the sanitizer residual and the pH and use that information to chemically treat the water. To check chlorine residual, free chlorine measurements are made. For automatic chlorine dosing systems, ORP must also be monitored to ensure proper functioning.

Free Chlorine is the amount of chlorine available as hypochlorous acid (HOCl-) and hypochlorite ion (OCl-), the concentrations of which are directly dependent on pH and temperature. pH is maintained at the level of greatest concentration of HOCl- because hypochlorous acid is a much more powerful sanitizer than hypochlorite ion. Free chlorine testing is usually required before and after opening of commercial pools. Samples should be taken at various locations to ensure even distribution. Residual levels are generally kept between 1-2 mg/L or ppm.* PooLPRo V.4.03 and later features the ability to measure ppm free chlorine in pools and spas sanitized by chlorine only. With this feature PoolPro can measure a dynamic range of chlorine concentrations wider than that of a colorimetric test kit with a greater degree of accuracy.

ORP stands for Oxidation Reduction Potential (or REDOX ) of the water and is measured in millivolts (mV). The higher the ORP, the greater the killing power of all sanitizers, not just free chlorine, in the water. ORP is the only practical method available to monitor sanitizer effectiveness. Thus, every true system of automatic chemical control depends on ORP to work.

The required ORP for disinfection will vary slightly between disinfecting systems and is also dependent on the basic water supply potential, which must be assessed and taken into account when the control system is initialized. 650 mV to 700 – 750 mV is generally considered ideal.*

Electronic controllers can  be inaccurate and inconsistent when confronted with certain unique water qualities, so it is critical to perform manual testing with separate instrumentation. For automatic control dosing, it is generally recommended that you manually test pH and ORP prior to opening and then once during the day to confirm automatic readings.*

Samples for confirming automatic control dosing should be taken from a sample tap strategically located on the return line as close as possible to the probes in accordance with the manufacturer’s instructions. If manual and automatic readings consistently move further apart or closer together, you should investigate the reason for the difference.*

ORP readings can only be obtained with an electronic instrument. PoolPro provides the fastest, most precise, easy-to-use method of obtaining ORP readings to check the effectiveness of the sanitizer in any pool or spa. This is the best way to determine how safe your water is at any given moment.

SALTWATER SANITATION

A relatively new development, saltwater pools use regular salt, sodium chloride, to form chlorine with an electrical current much in the same way liquid bleach is made. As chlorine – the sanitizer – is made from the salt in the water, it is critical to maintain the salt concentration at the appropriate levels to produce an adequate level of sanitizer. It is even more important to test water parameters frequently in these types of pools and spas, as saltwater does not have the ability to respond adequately to shock loadings (superchlorination treatments).

Most saltwater chlorinators require a 2,500 – 3,000 ppm salt concentration in the water (though some may require as high as 5,000-7,000 ppm).* This can barely be tasted, but provides enough salt for the system to produce the chlorine needed to sanitize the water.

(It is important to have a good stabilizer level – 30 – 50 ppm* – in the pool, or the sunlight will burn up the chlorine. Without it, the saltwater system may not be able to keep up with the demand regardless of salt concentration.)

Taste and salt shortages are of little concern to seawater systems that maintain an average of 32,000 ppm. In these high-salt environments, you need to beware of corrosion to system components that can distort salt level and other parameter readings.

Additionally, incorrect salt concentration readings can occur in any saltwater system. The monitoring/controlling components can and do fail or become scaled— sometimes giving a false low salt reading. Thus, you must test manually for salt concentration with separate instrumentation before adding salt.

You must also test salt concentration manually with separate instrumentation to re-calibrate your system. This is critical to system functioning and production of required chlorine. Both the PoolPro and PT1 conveniently test for salt concentration at the press of a button as a check against automatic controller systems that may have disabled equipment or need to be re-calibrated.

Though no one instrument or method can be used to determine ALL of the factors that affect the comfort and sanitation of pool and spa water, PoolPro is a comprehensive water testing instrument that is reliable durable, easy-to-use and easy-to-maintain and calibrate. As a pool professional, a PoolPro will not only simplify your life, it will save you time and money.

 RECORD KEEPING – WHAT TO DO WITH ALL THOSE MEASUREMENTS …

Data handling should be done objectively, and data recorded in a common format in the most accurate way. Also, data should be stored in more than one permanent location and made available for future analysis. Most municipalities require commercial aquatic facilities to keep permanent records on site and available for inspection at any time.

PoolPro makes it easy to comply with record keeping requirements. The PoolPro is an objective means to test free chlorine, ORP, pH, TDS, temperature and the mineral/salt content of any pool or spa. You just rinse and fill the cell cup by submerging the waterproof unit and press the button of the parameter you wish to measure. You immediately get a standard, numerical digital readout –  no interpretation required – eliminating all subjectivity. And model PS9TK features the added ability to perform in-cell conductometric titrations for Alkalinity, Hardness and LSI on the spot. Up to 100 date-time-stamped readings can be stored in memory and then later transferred directly to a computer wirelessly using the bluDock™ accessory package. Simply pair the bluDock with your computer, then open the U2CI software application to download data. The user never touches the data, reducing the potential for human error in transcription. The data can then be imported into any program necessary for record-keeping and analysis. The bluDock is a quick and easy way to keep records that comply with governing standards.*

*Consult your governing bodies for specific testing, chemical concentrations, and all other guidelines and requirements. The ranges and methods suggested here are meant as general examples.

Save 10% when you order online here at MyronLMeters.com.

Categories : Case Studies & Application Stories, Product Updates

Environmental Applications Bulletin – MyronLMeters.com

Posted by 4 Oct, 2012

TweetEnvironmental Applications Keeping the water in our lakes, rivers, and streams clean requires monitoring of water quality at many points as it gradually makes its way from its source to our oceans. Over the years ever-increasing environmental concerns and regulations have heightened the need for increased diligence and tighter restrictions on wastewater quality. Control of […]

Environmental Applications
Keeping the water in our lakes, rivers, and streams clean requires monitoring of water quality at many points as it gradually makes its way from its source to our oceans. Over the years ever-increasing environmental concerns and regulations have heightened the need for increased diligence and tighter restrictions on wastewater quality. Control of water pollution was once concerned mainly with treating wastewater before it was discharged from a manufacturing facility into the nation’s waterways. Today, in many cases, there are restrictions on wastewater that is discharged to city sewer systems or to other publicly owned treatment facilities. Many jurisdictions even restrict or regulate the runoff of storm water — affecting not only industrial and commercial land, but also residential properties as well.

In its simplest form, water pollution management requires impoundment of storm water runoff for a specified period of time before being discharged. Normally, a few simple tests such as pH and suspended solids must be checked to verify compliance before release. If water is used in any way prior to discharge, then the monitoring requirements can expand significantly. For example, if the water is used for once-through cooling, testing may include temperature, pH, total dissolved solids (TDS), chemical oxygen demand (COD), and biochemical oxygen demand (BOD), to name a few.

Once water is used in a process, some form of treatment is often required before it can be discharged to a public waterway. If wastewater is discharged to a city sewer or publicly owned facility, and treatment is required, the quality is often measured and the cost is based not only on the quantity discharged, but also the amount of treatment required. As a minimum requirement suspended solids must be removed. Filtering or using clarifiers often accomplishes such removal. Monitoring consists of measuring total suspended solids (TSS) or turbidity.

If inorganic materials have been introduced into the water, their concentration must be reduced to an acceptable level. Inorganics, such as heavy metals, typically are removed by raising the pH to form insoluble metal oxides or metal hydroxides. The precipitated contaminants are filtered or settled out. Afterward, the pH must be adjusted back into a “normal” range, which often requires continuous monitoring of pH.

Organic materials by far require the most extensive treatment. Many different methods have been devised to convert soluble organic compounds into insoluble inorganic matter. Most of these involve some form of biological oxidation treatment. Bacteria are used to metabolize the organic materials into carbon dioxide and solids, which can be easily removed. To insure that these processes work smoothly and efficiently requires regular monitoring of the health of the biological organisms. The level of food (organic material), nutrients (nitrogen and phosphorous), dissolved oxygen, and pH are some of the parameters that must be controlled. After bio-oxidation the wastewater is filtered or clarified. Often the final effluent is treated with an oxidizing compound such as chlorine to kill any remaining bacterial agents, but any excess oxidant normally must be removed prior to discharge. Oxidation Reduction Potential (ORP)/Redox is ideal for monitoring the level of oxidants before and after removal. The final effluent stream must be monitored to make sure it meets all regulatory requirements.

The monitoring of wastewater pollution does not end there. Scientists are continuously testing water in streams, ground water, lakes, lagoons, and other bodies of water to determine if and what effects any remaining contamination is having on the receiving waters and its associated aquatic life. Measurements may include pH, conductivity, TDS, temperature, dissolved oxygen, TSS and organic levels (COD and BOD).

Environmental testing is not limited to monitoring of wastewater systems. Control of air emissions often includes gas-cleaning systems that involve the use of water. Wet scrubbers and wet electrostatic precipitators are included in this group. A flue gas desulfurization (FGD) system is one type of wet scrubber that uses slurry of lime, limestone, or other caustic material to react with sulfur compounds in the flue gas. The key to reliable operation of these units is proper monitoring of solids levels and pH. After use, the water in these systems must be treated or added to other wastewater from the plant, where it is treated by one of the methods previously discussed.
With proper monitoring, systems that maintain cleaner air and water can be operated efficiently and effectively. Such operation will go a long way toward maintaining a cleaner environment for future generations.

Myron L Meters offers a full line of handheld instruments and in-line monitor/controllers that can be used to measure or monitor many of the parameters previously mentioned. The following table lists some of the model numbers for measuring, monitoring, or controlling pH, conductivity, TDS and ORP. For additional information, please refer to our data sheets or Ask An Expert at MyronLMeters.com.

Note: When using a monitor/controller to measure pH in streams that contain heavy metals, sulfides, or other materials that react with silver, Myron L Meters recommends using a double junction pH sensor with a potassium nitrate (KNO3) reference gel to avoid fouling the silver electrode. See our 720II Sensor Selection Guide for pH and ORP Monitor/controllers for more information.
Recommended handheld:

Ultrameter II 6P

 

 

 

 

 

 

 

 

http://www.myronlmeters.com/Ultrameter-II-6P-Multiparameter-Meter-p/dh-umii-6pii.htm

Multi-Parameter: Conductivity, TDS, Resistivity, pH, ORP, Temperature, Free Chlorine (FCE)
+/-1% Accuracy of Reading
Memory Storage: Save up to 100 samples w/ Date & Time stamp
Wireless Download Module Optional
Waterproof

 

Categories : Case Studies & Application Stories, Science and Industry Updates

Ultrapen PT3 pen – Tests ORP / REDOX and Temperature – MyronLMeters.com

Posted by 23 Sep, 2012

TweetThe All NEW ULTRAPEN PT3 pen tests ORP / REDOX and Temperature with great reliability. Advanced features include highly stable microprocessor-based circuitry; automatic temperature compensation from 15ºC to … [Learn more about the ULTRAPEN PT3 pen NOW!]

The All NEW ULTRAPEN PT3 pen tests ORP / REDOX and Temperature with great reliability. Advanced features include highly stable microprocessor-based circuitry; automatic temperature compensation from 15ºC to … [Learn more about the ULTRAPEN PT3 pen NOW!]

Ultrapen PT3 instrument diagram

Categories : Product Updates