Calibrate Conductivity on the Ultrameter II 6PII

Posted by 22 Mar, 2014

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Ultrameter II 6PII, how to calibrate conductivity. Learn how to use the digital handheld water quality meters to take readings for conductivity. The Ultrameter II 6PII

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Questions About Inline Monitors, Controllers, Aquaswitches:

Posted by 20 Mar, 2014 is the premier online distributor of Myron L Instruments. We make it easy to shop for your water quality testing instruments online. We understand that in order to make a buying decision you need more than just a recommendation or a product description. At you will find detailed information about every product, including demo videos and customer reviews.

Since the 1960s, Myron L products have led the industry in high quality, simple to operate conductivity and pH instrumentation for municipal, commercial and industrial water quality control, chemical concentration testing and process control. Today, Myron L meters are more convenient than ever to research and buy right here at We provide the background, insight, product imagery and specifications you need to make the right choice–all in one convenient online store. Have questions that aren’t answered in our FAQ section or on the blog? Ask an expert by filling out a short form and we’ll respond with an answer within 24 hours. At our mission is simple: Provide the best products with the best service, every day. We are proud to represent a quality product from a quality manufacturer!

My 750 Series II Monitor or Monitor/Controller display shows a 1, then a space, then a decimal point. What does this mean?
This is an over-range condition that can be fixed by performing an Electronic calibration of the circuit board. Please see directions in the Operations Manual or follow this brief review of Electronic Calibration. Hook up a Multi-Meter to the R+ and R- leads located at the top of the circuit board, switch the Multi-Meter to DC volts, push the Full Scale Push to Test button and read the DC voltage on the Multi-Meter. While pushing the Full Scale Push to Test button, adjust the CAL screw on the circuit board until the Multi-Meter reads 9.95-10.00 VDC. The display on the Myron L Monitor or Monitor/Controller should now read Full Scale.

How do I pick the correct range module for my Monitor or Monitor/Controller?
You must pick a range module that covers your 2/3 of your operating range. If you pick a range module that is too broad, then your accuracy will suffer or it will not show a number on the display. For example, if your operating range is 100-150 microsiemens, a range module of 0-200 microsiemens (-115) would be a good choice. A range module of 0-5,000 microsiemens (-123) would not be a good choice for this application.

Why does my displayed number fluctuate?
There is air or air bubbles around the sensor or the sensor is not properly installed. Tap on the sensor body to dislodge air bubbles or loosen securing nut to release trapped air. The sensor tip must be in the flow of water.

My device connected to the dry contact relay does not work and has no power. What do I do?
The Myron L dry contact relay does not draw power from the circuit board. You must supply the power to the relay to power your device.

Why is the display number on the Monitor or Monitor/Controller negative?
This is the offset that is being display and is caused when the sensor is not hooked up or is hooked up and sitting in air.

Why is the displayed number on the Monitor or Monitor/Controller half the reading than it should be?
This is caused when the 115/230 VAC switch is set to 230VAC when in fact it should be switched to 115 VAC.

Does the Aquaswitch I require any other device to help it switch banks?

Yes, the AquaSwitch I requires a Monitor/Controller in order to switch banks.

What is the recommended method to mount a Conductivity or Resistivity sensor?
The optimal method to mount the sensor is in the end of a tee with the water flowing directly into the tip of the sensor and flowing up and away at a 90 degree angle. Please see the 750 Series II Operations Manual for complete instructions.

I want to use my Monitor or Monitor/Controller for another application but the water quality is a totally different range. Can my existing unit be changed?
Our 750 Series II Conductivity/TDS and Resistivity Monitors and Monitor/Controllers can be “Re-Ranged” with a new range module to meet you changing needs. Simply un-plug the old range module and plug in the new range module into the circuit board. Refer to page 8 of the Operations Manual to see the Range Selection guide and to see if any minor modifications are necessary.

How can I tell what the model number of my Monitor or Monitor/Controller is?
The module number is circled on the transformer and printed on the back of the case.

Have other questions?  Try our literature database HERE, our video channel HERE, or use the handy Ask An Expert contact form at

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

pH and ORP Sensors for Inline Monitor/Controllers:

Posted by 19 Mar, 2014

All Myron L pH and Oxidation Reduction Potential or ORP sensors are combination pH/reference, or ORP/reference. These sensors are designed to operate with Myron L 720 Series II pH and ORP Monitor/controllers. Each sensor has a built-in isolated preamplifier that guarantees accurate and reliable measurements — completely eliminating ground-loops and noise issues. The preamp allows for longer distances between the sensor and our Monitor/controller without the loss of accuracy or reliability due to cable capacitance, resistance, or noise.

Our preamp is so simple and low cost that we build it right into the sensor, thus allowing for a truly sealed sensor system — no O-rings to become damaged and leak, no BNC connectors to corrode and cause unreliable readings. It is actually no more expensive than the BNC connectors and coax cable it replaces.

All pH sensors include a built-in Temperature Sensor for automatic Temperature Compensation (TC). The TC may be disabled, requirements per USP, or if a separate temperature device is required for your SCADA system.

All bodies are made of Schedule 80 Chlorinated Polyvinyl Chloride (CPVC) or Ryton®* Polyphenylene Sulfide (PPS) to withstand the demanding requirements of most applications. Choice of double ended 1/2” or 3/4” MNPT body allows for ease of installation in either in-line or submersion applications. All Myron L sensors are completely encapsulated and sealed to keep out moisture and to assure long life under demanding conditions. Just install and use. Overall length is ~165 mm/6.5 in. Standard cable length is 3 meters/ 10 ft. Sensors may be ordered with 8 meter/25 ft. or 30 meter/100 ft. lengths. Cable may be extended simply and without problems. We recommend a junction box to protect the splice.

For in-line use, simply install sensor into female threaded fitting or tee. For submersion use, simply install into user supplied pipe coupling and extension pipe.

• Built-in isolated preamp guarantees accurate, trouble
free operation.

• Temperature Sensor built-in for automatic Temperature
Compensation (may be disabled as required).

• All sensors are double ended MNPT for simple in-line
or submersion applications.

• All sensors are pH/reference, or ORP/ reference, or a
combination of the two.
• CPVC/Ryton® bodies assure compatibility in most

• All sensors are completely encapsulated and sealed.

• Sensor cable may be extended simply, without problems.

• All ORP sensors have an extended tip Platinum
electrode except “F” models.

• Heavy Duty “F” models may be installed in ANY
direction, including inverted.

Sensor specs







In the specific descriptions below, substitute ORP for pH where

General Purpose Single Junction
Low Cost In-line/Submersion pH and ORP Sensors.
The Single Junction “S” reference sensor is used for simple, non-demanding applications. It uses Potassium Chloride (KCI) reference gel. Response time, generally 95% in one second. For intermittent use up to 100°C/212°F @ 3,45 bar/50 psi. Twelve (12) month shelf life. This is our most economical sensor.

Special Purpose Double Junction
Low Cost In-line/Submersion pH and ORP Sensors.
The Double Junction “D” reference sensor is used in more demanding applications where “poisoning” of the reference is a possibility or a concern. It uses Potassium Nitrate (KNO3) gel where the reference meets the solution. This sensor is an ideal, cost effective alternative for demanding environmental applications not requiring the added advantages of the Heavy Duty Flat Tip sensor listed below. Response time, generally 95% in one second. When in doubt it is best to select a Double Junction sensor. Twelve (12) month shelf life. This sensor is the ideal, most cost effective Double Junction sensor on the market.

Low Conductivity

Low Cost In-line/Submersion pH and ORP Sensors.
The Low Conductivity “LC” sensor is recommended when the pH or ORP of low conductivity (low ionic strength) solutions must be measured. This sensor utilizes a porous polyethylene Double Junction with a low molar (0.1) KCI gel in the reference meeting the solution. This low molar reference more closely matches the low ionic strength of the solution, which allows more stable readings and cuts down in the contamination of the solution being measured. The LC sensor is recommended for use in RO/DI applications with solutions less than 100 µM/
µS/ppm. Twelve (12) month shelf life. This sensor is made for special, low conductivity applications.

Heavy Duty
Low Cost In-line/Submersion pH and ORP Sensors.
The Heavy Duty “F” utilizes a FLAT-TIP self cleaning sensor (flat glass in place of a round bulb) for use where the most demanding applications are found, such as wastewater. The flat tip will last longer in most abrasive and/or oily solution environments. These sensors utilize a HDPE (High Density Polyethylene) Double Junction reference with a high temperature
— chemical resistant acrylamide gel. Response time, generally 95% in five seconds. For continuous use 100°C/212°F @ 3,45 bar/50 psi, 81°C/178°F @ 5,86 bar/85 psi, and 76°C/169°F @ 6,9 bar/100 psi. Six (6) month shelf life. This sensor may be installed in ANY direction including INVERTED, and is simply the BEST sensor for tough applications.

Note: High flow reference junctions (HDPE, Kynar and Teflon) are available on above models upon special order. These special junctions will help keep the reference from clogging as easily — in some applications, however, they will deplete the reference gel more quickly, and thus have a shorter shelf/use life.

ALL pH and ORP sensors are life limited. For this reason, it is recommended that extra sensors be kept on hand for all process applications. To obtain the maximum life, ALWAYS store sensor in pH/ORP Sensor Storage Solution when not in use. DO NOT allow sensor to dry out.

Sensor Part numbers


Sensor diagram


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Categories : Product Updates

Ultrameter II : Cleaning the sensor –

Posted by 9 Mar, 2014

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This video is about Ultrameter II cleaning the sensor

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Testing Fountain Solutions:

Posted by 6 Mar, 2014

Need to know the best meter for your application? Review our Bulletins which explain in clear detail the best model for your needs. If you have more questions, visit our FAQ section or send our Experts a question using the contact form. We’ll respond as quickly as possible! Visit for videos, operations manuals, FAQ, MSDS, and more information about Myron L meters.

Fountain Solutions
Accurate fountain (dampening) solution concentration control is essential for consistent, high-quality results in lithography. Low concentration can cause drying on the non-image area of the plate resulting in tinting, scumming, blanket piling, etc. High concentrations, on the other hand, bring about over-emulsification of the ink. This results in weakening of color strength and changes in ink rheology (body and flow properties). Correct concentration will allow the non-image areas of the plate to be appropriately wetted.

Ways to Test

Traditionally, pH was the test relied on to determine fountain solution concentration. Today, however, conductivity testing is recognized as a much more accurate method. Many modern dampening solutions are pH stabilized (or buffered), so only small changes in pH are seen even when dramatic changes occur in solution strength. Conductivity measurement is a fast and easy test which is more indicative of fountain solution concentration than pH. This is true for all neutral, alkaline, and many acid type solutions.

pH is still important, however, with unbuffered acid fountain solutions. Checking both conductivity and pH can provide valuable information. Acid fountain solution is a mixture of gum arabic, wetting agents, salts, acids, buffers, etc. Conductivity will tell you if the proper amount of most ingredients are present, but pH is necessary to check acid concentrations. pH will also determine how effective one ingredient, gum arabic, will be.

Conductivity Testing

What is conductivity? Conductivity is the measurement of a solution’s ability to conduct an electrical current. It is usually expressed in microsiemens (micromhos). Absolutely pure water is actually a poor electrical conductor. It is the substances dissolved in water which determine how conductive the solution will be. Therefore, conductivity is an excellent indicator of solution strength. To properly measure the conductivity of fountain solutions:

Test and write down the conductivity of the water used to prepare the solution.
Mix the fountain solution concentrate with the water, using the manufacturer’s recommendations or as experience dictates.
Measure the conductivity of the mixed solution.
Subtract the water conductivity value obtained in step 1. This is necessary because tap water quality can change from day to day.

The resulting number is an accurate indicator of fountain solution strength. Caution: because alcohol will lower a solution’s conductivity, always test solution conductivity before and after the addition of alcohol.

Determining the best concentration of fountain solution is mostly ‘trial and error.’ It can be very useful to make a graph, recording readings for every one-half or one ounce of concentrate added to a gallon of water. Record readings on a graph with the vertical axis representing conductivity values and the horizontal axis representing ounces/gallon. Such a graph will help ‘fine tune’ your system during future press runs.
For ‘on the spot’ fountain solution tests, Myron L meters are fast, accurate, and reliable. Measurements are made in seconds simply by pouring a small sample of solution into the instrument cell cup and pressing a button. Automatic temperature compensated accuracy and reliability have made our instruments popular in pressrooms worldwide.

pH Testing

Even though pH usually is not the best method to check the concentration of fountain solution, it is still very important and must be checked regularly. The pH of acid dampening solution affects sensitivity, plate-life, ink-drying, etc. Also, pH can change during a run if the paper has a high acid or alkaline content. pH, therefore, must be maintained at the proper level for good printing.

A convenient and accurate way to test pH (as well as temperature) is the waterproof ULTRAMETER II Model 6P or TECHPRO II TH1. The 6P has a 100 reading memory and the TH1 has a 20 reading memory to store test results onsite. The 6P also measures conductivity. All electrodes are contained in the cell cup for protection. Model M6/PH also measures pH and conductivity.

Continuous Control

For continuous monitoring and/or control of fountain solution concentration, we offer a complete series of in-line conductivity instruments. These economical, accurate, and reliable models use a remotely installed sensor and a panel/wall mount meter enclosure. Most contain an adjustable set point and heavy duty relay circuit which can be used to activate alarms, valves, feed pumps, etc. All models contain a 0-10VDC output for a chart recorder or PLC (SCADA) input, if required, (4-20mA output is also available).

The 750 Series II with dual set point option has become quite popular in pressrooms. The two set points allow a ‘safe zone’ for controlling fountain solution concentration.


Ultrameter II 6P, 512M5 and M6/PH are available with the useful LITHO-KIT. This accessory includes a foam-lined, rugged all-plastic carrying case with calibrating solutions and buffers. In addition, a syringe to simplify drawing samples and a thermometer for testing fountain solution temperature are also included.



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

Posted by 2 Mar, 2014
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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:

Categories : Videos

Ultrameter: Measuring Conductivity, TDS and Resistivity:

Posted by 1 Mar, 2014

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:


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

Categories : Application Advice, Technical Tips

Conductivity Conversion to TDS in the Ultrameter:

Posted by 1 Mar, 2014

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.


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.


Figure 33


Glass Surface

H+ ions

Junction plug
Platinum button


KCl solution






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, the premier internet retailer of Myron L products. Save 10% on the Myron L Ultrameter II6 PFCe when you order online here:


Categories : Application Advice, Technical Tips

Recommended Ultrameter Solutions and Accessories:

Posted by 1 Mar, 2014

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:

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:

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:

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:

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:

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:

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:

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:

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:

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

Categories : Product Updates

Cleaning The Ultrameter II 6P Sensors:

Posted by 1 Mar, 2014


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.


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:  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.









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.


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:

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


Categories : Care and Maintenance, Technical Tips