Archive for March, 2014

Ultrameter II Cleaning the conductivity & TDS sensor – Myron L Meters

Posted by 2 Mar, 2014

Tweet[mc4wp_form] This video is about cleaning the Ultrameter II conductivty and TDS sensor. Learn the steps for using isopropyl alcohol or Lime-A-Way to clean the sensor to get accurate readings. If you are having trouble during calibration of the conductiivty and tds parameters then you can follow these steps. Order the Myron L Ultrameter II […]

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This video is about cleaning the Ultrameter II conductivty and TDS sensor. Learn the steps for using isopropyl alcohol or Lime-A-Way to clean the sensor to get accurate readings. If you are having trouble during calibration of the conductiivty and tds parameters then you can follow these steps.

Order the Myron L Ultrameter II here: https://www.myronlmeters.com/Ultrameter-II-s/55.htm

Categories : Videos

Ultrameter: Measuring Conductivity, TDS and Resistivity: MyronLMeters.com

Posted by 1 Mar, 2014

TweetPlease note:  These procedures apply to Ultrameters, Pool Pros, Tech Pros, and D-4 and D-6 dialysate meters. Measuring Conductivity & TDS 1. Rinse cell cup 3 times with sample to be measured. (This conditions the temperature compensation network and prepares the cell.) 2. Refill cell cup with sample. 3. Press COND or TDS. 4. Take […]

Please note:  These procedures apply to Ultrameters, Pool Pros, Tech Pros, and D-4 and D-6 dialysate meters.

Measuring Conductivity & TDS

1. Rinse cell cup 3 times with sample to be measured. (This conditions

the temperature compensation network and prepares the cell.)

2. Refill cell cup with sample.

3. Press COND or TDS.

4. Take reading. A display of [- – – -] indicates an over range condition.

Measuring Resistivity

Resistivity is for low conductivity solutions. In a cell cup the value may drift from trace contaminants or absorption from atmospheric gasses, so measuring a flowing sample is recommended.

1. Ensure pH protective cap is secure to avoid contamination.

2. Hold instrument at 30° angle (cup sloping downward).

3. Let sample flow continuously into conductivity cell with no aeration.

4. Press RES key; use best reading.

NOTE: If reading is lower than 10 kilohms display will be dashes: [ – – – – ]. Use Conductivity.

If you have further questions, please watch our Ultrameter 6P product overview video here: http://blog.myronlmeters.com/ultrameter-ii-product-review/

 IV. AFTER USING THE ULTRAMETER II

Maintenance of the Conductivity Cell

Rinse out the cell cup with clean water. Do not scrub the cell. For oily films, squirt in a foaming non-abrasive cleaner and rinse. Even if a very active chemical discolors the electrodes, this does not affect the accuracy; leave it alone.

Myron L Meters is the premier internet retailer of Myron L meters, solutions, parts and accessories. Save 10% on the Ultrameter II 6PFCe when you order online at MyronLMeters.com.

Categories : Application Advice, Technical Tips

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.

Capture

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

Recommended Ultrameter Solutions and Accessories: MyronLMeters.com

Posted by 1 Mar, 2014

TweetA.           Conductivity/TDS Standard Solutions Your Ultrameter II has been factory calibrated with the appropriate Myron L NIST traceable KCl, NaCl, and our own 442™ standard solutions. Most Myron L conductivity standard solution bottles show three values referenced at 25°C: Conductivity in microsiemens/ micromhos, the ppm/TDS equivalents (based on our 442 Natural Water™) and NaCl standards. […]

A.           Conductivity/TDS Standard Solutions

Your Ultrameter II has been factory calibrated with the appropriate Myron L NIST traceable KCl, NaCl, and our own 442™ standard solutions. Most Myron L conductivity standard solution bottles show three values referenced at 25°C: Conductivity in microsiemens/ micromhos, the ppm/TDS equivalents (based on our 442 Natural Water™) and NaCl standards. All standards are within ±1.0% of reference solutions.

1.            Potassium Chloride (KCl)

The concentrations of these reference solutions are calculated from data in the International Critical Tables, Vol. 6. The 7000 µS is the recommended standard. Order KCL-7000 here: http://www.myronlmeters.com/Myron-L-KCL-7000-uS-32-oz-calibration-solution-p/s-kcl-7000q.htm

2.            442 Natural Water™

442 Natural Water Standard Solutions are based on the following salt proportions: 40% sodium sulfate, 40% sodium bicarbonate, and 20% sodium chloride, which represent the three predominant components (anions) in freshwater. This salt ratio has conductivity characteristics approximating fresh natural waters and was developed by Myron L over four decades ago. It is used around the world for measuring both conductivity and TDS in drinking water, ground water, lakes, streams, etc. 3000 ppm is the recommended standard. Order 442-3000 here: http://www.myronlmeters.com/442-3000-ppm-TDS-calibration-solution-32oz-quart-p/s-442-3000q.htm

Order 442-3000

3. Sodium Chloride (NaCl)

This is especially useful in sea water mix applications, as sodium chloride is the major salt component. Most Myron L standard solution labels show the ppm NaCl equivalent to the conductivity and to ppm 442 values. The 14.0 mS is the recommended standard. Order NACL-14.0 here: http://www.myronlmeters.com/Myron-L-NACL-14-0-mS-32-oz-calibration-solution-p/s-nacl-14.0q.htm

B.           pH Buffer Solutions (6PFCE)

pH buffers are available in pH values of 4, 7 and 10. Myron L buffer solutions are traceable to NIST certified pH references and are color-coded for instant identification. They are also mold inhibited and accurate to within ±0.01 pH units @ 25°C. Order 4, 7 or 10 Buffers here: http://www.myronlmeters.com/pH-Buffer-Calibration-Solutions-s/82.htm

C.           pH Sensor Storage Solution (6PFCE)

Myron L pH Sensor Storage Solution prolongs the life of the pH sensor.

Order Ultrameter pH/ORP Sensor Storage solution here: http://www.myronlmeters.com/Myron-L-pH-ORP-Sensor-Storage-Solutions-32-oz-p/s-ssq.htm

D.           Soft Protective Carry Cases

Padded Nylon carrying case features a belt clip for hands-free mobility. Two colors to choose from:

Blue – Model #: UCC  Desert Tan – Model #: UCCDT  Order your UCC Ultrameter carrying case here: http://www.myronlmeters.com/Myron-L-UCC-Canvas-Case-p/a-ucc.htm

E.            Hard Protective Carry Cases

Large case with 2 oz. bottles of calibration standard solutions (KCl-7000, 442-3000, 4, 7, & 10 pH buffers and pH storage solution). Model #: PKUU Small case (no calibration standard solutions) – Model #: UPP

Order your PKUU Ultrameter hard carrying case here: http://www.myronlmeters.com/Myron-L-PKUU-Porta-kit-Digital-Meter-Carrying-Case-p/a-pkuu.htm

F.            Replacement pH/ORP Sensor (Ultrameter 6PFCE)

pH/ORP sensor is gel filled and features a unique porous liquid junction.

It is user-replaceable and comes with easy to follow instructions.

Model #: RPR  Order your Ultrameter replacement pH/ORP sensor here: http://www.myronlmeters.com/Myron-L-RPR-Ultrameter-pH-ORP-Sensor-p/a-rpr.htm

G.           bluDock™ Wireless Data Transfer Accessory Package

This accessory lets you download the Ultrameter II stored readings to a spreadsheet on a computer. The package includes a bluDock modified circuit board in the unit, software CD, installation and operating instructions, and dongle. Model #: BLUDOCK Order your Ultrameter bluDock here: http://www.myronlmeters.com/Myron-L-BluDock-Wireless-Download-Module-p/a-bd.htm

Myron L Meters is the premier internet source for Myron L meters, solutions, parts and accessories.  Save 10% on Myron L meters when you order online at MyronLMeters.com

Categories : Product Updates

Cleaning The Ultrameter II 6P Sensors: MyronLMeters.com

Posted by 1 Mar, 2014

TweetConductivity/TDS/Resistivity The conductivity cell cup should be kept as clean as possible. Flushing with clean water following use will prevent buildup on electrodes. However, if very dirty samples — particularly scaling types — are allowed to dry in the cell cup, a film will form. This film reduces accuracy. When there are visible films of […]

Conductivity/TDS/Resistivity

The conductivity cell cup should be kept as clean as possible. Flushing with clean water following use will prevent buildup on electrodes. However, if very dirty samples — particularly scaling types — are allowed to dry in the cell cup, a film will form. This film reduces accuracy. When there are visible films of oil, dirt, or scale in the cell cup or on the electrodes, use isopropyl alcohol or a foaming non-abrasive household cleaner. Rinse out the cleaner and your Ultrameter II is again ready to use.

pH/ORP (6PFCE)

The unique pH/ORP sensor in your Ultrameter II  is a nonrefillable combination type that features a porous liquid junction. It should not be allowed to dry out. To keep it from drying out and to prolong the life of the sensor, use SS sensor storage solution found here: http://www.myronlmeters.com/Myron-L-pH-ORP-Sensor-Storage-Solutions-32-oz-p/s-ssq.htm.  However, if this occurs, the sensor may sometimes be rejuvenated by first cleaning the sensor well with Isopropyl alcohol or a liquid spray cleaner such as Windex™ or Fantastic™ and rinsing well. Do not scrub or wipe the pH/ORP sensor.

Capture

 

 

 

 

 

 

 

Then use one of the following methods:

1.            Pour a HOT salt solution ~60°C/140°F — a potassium chloride (KCI) solution such as Myron L pH/ORP Sensor Storage Solution is preferable, but HOT tap water with table salt (NaCl) will work fine — in the sensor well and allow to cool. Retest.

or

2.            Pour DI water in the sensor well and allow to stand for no more than 4 hours (longer can deplete the reference solution and damage the glass bulb). Retest. If neither method is successful, the sensor must be replaced.

“Drifting” can be caused by a film on the pH sensor bulb and/or reference. Use isopropyl alcohol (IPA) or spray a liquid cleaner such as Windex™ or Fantastic™ into the sensor well to clean it. The sensor bulb is very thin and delicate. Do not scrub or wipe the pH/ORP sensor. Leaving high pH (alkaline) solutions in contact with the pH sensor for long periods of time is harmful and will cause damage. Rinsing such liquids from the pH/ORP sensor well and refilling it with Myron L Storage Solution, a saturated KCl solution, pH 4 buffer, or a saturated solution of table salt and tap water, will extend the useful life.

Samples containing chlorine, sulfur, or ammonia can “poison” any pH electrode. If it is necessary to measure the pH of any such sample, thoroughly rinse the sensor well with clean water immediately after taking the measurement. Any sample element that reduces (adds an electron to) silver, such as cyanide, will attack the reference electrode.

Replacement sensors are available here:  http://www.myronlmeters.com/Myron-L-RPR-Ultrameter-pH-ORP-Sensor-p/a-rpr.htm

Myron L Meters is your best internet source for Ultrameter 6P parts and accessories.  You can always save 10% on Myron L meters when you order online at MyronLMeters.com.

 

Categories : Care and Maintenance, Technical Tips