Measuring Key Water Quality Parameters: MyronLMeters.com

Posted by 12 Apr, 2014

TweetThe right meter is essential for measuring any of several key water quality parameters:Conductivity is the ability of water to conduct an electrical current and is an indirect measure of the conductive ionic mineral concentration. The more conductive ions that are present, the more electricity can be conducted by the water. This measurement is expressed […]

The right meter is essential for measuring any of several key water quality parameters:

Conductivity is the ability of water to conduct an electrical current and is an indirect measure of the conductive ionic mineral concentration. The more conductive ions that are present, the more electricity can be conducted by the water. This measurement is expressed in microsiemens per centimeter (µS/cm) at 25º Celsius. Myron L Meters carries a complete line of conductivity meters, including the Ultrameter II 4P.

Resistivity is the inverse of conductivity. Electrical conductivity is a measure of water’s resistance to an electric current. Water itself has a weak electrical conductivity. Electric current is transported in water by dissolved ions, making conductivity measurement a quick and reliable way to monitor the total amount of ionic contaminants in water. Myron L Meters carries a complete line of resistivity meters, including inline monitor/controllers like the 753II Resistivity Digital Monitor/Controller.

Total Dissolved Solids (TDS) is also a measurement of the amount of dissolved minerals in the water. In this instance they would be called solids in solution. The quantity of dissolved solids in the solution is directly proportional to the conductivity. In this case, conductivity is the measurement but it is used to estimate TDS. It is measured with a conductivity meter but is reported as TDS in parts per million (ppm), via a complex algorithm. Myron L Meters carries a complete line of TDS meters, including the Ultrapen PT1.

pH is a measure of the concentration of hydrogen ions in the water, indicating the acidity or alkalinity of the water. On the pH scale of 0-14, a reading of 7 is considered to be neutral. Readings below 7 indicate acidic conditions, while readings above 7 indicate the water is alkaline or basic. Naturally occurring fresh waters have a pH range between 6 and 8. Myron L Meters carries a complete line of pH meters, including the Ultrapen PT2

Temperature is expressed in degrees Celsius (C) or Fahrenheit (F). Most digital handheld Myron L Meters include a temperature function.



Oxidation reduction potential (ORP)can correlate millivolt readings to the sanitization strength of the water. Microbes can cause corrosion, fouling, and disease, and oxidizing biocides are usually used to keep microbial levels under control. ORP is expressed in millivolts (mV). Myron L Meters carries a complete line of ORP meters, including the Ultrapen PT3

Free Chlorine refers to both hypochlorous acid (HOCl) and the hypochlorite (OCl–) ion or bleach, and is commonly added to water systems for disinfection. Free chlorine is typically measured in drinking water disinfection systems to find whether the water system contains enough disinfectant.  Myron L Meters Ultrameter II 6PFCe and Ultrapen PT4 can both be used to measure free chlorine.

Salinity is simply a measure of the amount of salts dissolved in water, a measurement useful to pool service technicians and others.  You can measure salinity with a Myron L Pool Pro PS6.

Alkalinity is a measure of the capacity of water or any solution to neutralize or “buffer” acids. This measure of acid-neutralizing capacity is important in figuring out how “buffered” the water is against sudden changes in pH. Alkalinity is a titration function of the Ultrameter III 9PTKA.

Hardness is caused by compounds of calcium and magnesium, and by a variety of other metals.  As water moves through soil and rock, it dissolves very small amounts of minerals and holds them in solution. Calcium and magnesium dissolved in water are the two most common minerals that make water “hard.” Hardness is a titration function of the Ultrameter III 9PTKA.

LSI or Langelier Saturation Index helps you determine the scaling potential of water. LSI is a calculated number used to predict the calcium carbonate stability of water. It indicates whether the water will precipitate, dissolve, or be in equilibrium with calcium carbonate. LSI is a titration function of the Ultrameter III 9PTKA.

MyronLMeters.com is the premier internet retailer of accurate, reliable Myron L meters.  Save 10% when you order Myron L meters online at MyronLMeters.com. You’ll find reliable instruments for every water quality parameter mentioned above.



 

 

 

Categories : Uncategorized

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

Calibrating the Ultrapen PT3 ORP Pen: MyronLMeters.com

Posted by 4 Apr, 2014

TweetCalibration of the Ultrapen PT3 ORP Pen The factory recommends calibrating twice a month, depending on usage. However, you should check the calibration whenever measurements are not as expected. NOTE: If the measurement is NOT within calibration limits for any reason, “Error” will display. Check to make sure you are using a proper ORP calibration […]

how to calibrate orp with the ultrapen pt3

how to calibrate orp with the ultrapen pt3

Calibration of the Ultrapen PT3 ORP Pen
The factory recommends calibrating twice a month, depending on usage. However, you should check the calibration whenever measurements are not as expected.
NOTE: If the measurement is NOT within calibration limits for any reason, “Error” will display. Check to make sure you are using a proper ORP calibration solution. If the solution is correct, clean the sensor as described im the manual under Routine Maintenance. (Reconditioning the sensor should not be necessary due to the high ionic strength of the calibration solutions.) Restart calibration.
NOTE: Small bubbles trapped in the sensor may give a false calibration. After calibration is completed, measure the ORP calibration solution again to verify correct calibration. Remember, in measurement mode you must manually correct for temperature variance from 25ºC. Example: At 25ºC, ORP2602OZ calibration solution will read 260mV; however, at 20.0ºC ORP2602OZ will read 265mV.
NOTE: If at any point during calibration, you do not submerge the sensor in solution
before the flashing slows, allow the PT3 to turn off and start over.

A. Calibration Preparation
1. Ensure the ORP sensor is clean and free of debris.
2. For maximum accuracy, pour a small amount of the calibration solution into a separate container to rinse the sensor in prior to calibration. If this is not possible, rinse the sensor in clean water prior to calibration.

B. Calibration
Use Myron L Company 80mV Quinhydrone, 260mV Quinhydrone, or 470mV Light’s ORP Calibration Solution.
1. Thoroughly rinse the PT3 by submerging the sensor in ORP calibration rinse solution and swirling it around.
2. Push and release the push button to turn the PT3 on.
3. Push and hold the push button. The display will alternate between “CAL”, “FAC CAL”, “ºCºF TEMP”, “ModE SEL” and “ESC”.
4. Release the button when “CAL” displays. The display will indicate “CAL” and
the LED will flash rapidly.
5. While the LED flashes rapidly, dip the PT3 in ORP calibration solution so that
the sensor is completely submerged.
6. While the LED flashes slowly, the display will indicate “ [value] CAL”; swirl the
PT3 around to remove bubbles, keeping the sensor submerged.
7. If the ORP calibration is successful, the display will indicate “CAL SAVEd”, then time out.
8. Verify calibration by retesting the calibration solution.

C. Factory Calibration
When ORP calibration solution is not available, the PT3 can be returned to factory default calibration using the FAC CAL function. This will erase any stored wet calibration.
NOTE: default factory calibration resets the electronics only and does NOT take the condition of the sensor into consideration.
To return your PT3 to factory calibration:
1. Push and release the push button.
2. Push and hold the push button. The display will alternate between “CAL”, “FAC CAL”, “ºCºF TEMP”, “ModE SEL” and “ESC”.
3. Release the button when “FAC CAL” displays. The display will alternate between “PUSHnHLD” and “FAC CAL”.
4. Push and hold the push button until “SAVEd FAC” displays indicating the PT3 has been reset to its factory calibration.

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 […]

 

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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

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

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