Frequently Asked Questions

No, using liquid standards to calibrate values between 18 µS (55,555 Ω) and 0.05 µS (18,000,000 Ω) are not practical due to carbon dioxide contamination from the atmosphere.  A solution of 18 megohm-cm will degrade to approximately 1 megohm-cm if allowed to stand in open air.

A resistivity monitor/controller can have its electronics calibrated using a cell substitute.  This is a module that is comprised of accurate fixed resistors that are installed in place of the actual resistivity electrode.  Once the cell sub is installed the electronics can be calibrated very accurately.  Contact your Myron L^® distributor to obtain information regarding the cell sub.

No, unlike the in line resistivity monitor/controller, the Myron L^® Ultrameter handheld instrument combines the unique ability to measure conductivity (0 to 200 mS) and resistivity (10 KΩ to 30 MΩ) ranges into one microprocessor based instrument.  Since resistivity is the reciprocal of conductivity, the instrument only requires the calibration of a conductivity range using a Myron L^® standard.  Once a liquid standard is used to properly calibrate a conductivity range, this will automatically ensure accurate measurements throughout the resistivity ranges.

Note: The resistivity ranges are calibrated only if the conductivity ranges are calibrated for the same solution.  When using the Ultrameter to measure ultra pure water, a special technique is required to capture the water in the sensor well to reduce the affects of carbon dioxide in the sample.  For detailed information on the calibration and the use of the EP, see the EP instruction manual.  For detailed information on the calibration and use of the Ultrameter, see the Ultrameter operation manual.

The Myron L^® Company warranty on all standards and buffers is one year from the date it is manufactured (see the label on the bottle).  If the standards and buffers become contaminated by the user pouring test samples back into the bottle or inserting the probe into the bottle the solution will not be accurate and should be discarded.  The life of Myron L^® standards and buffers can exceed 1 year if the bottle is stored tightly capped and is not exposed to direct sunlight or freezing temperatures.  If the solution becomes frozen, do not remove the cap - allow the standard or buffer solution to thaw completely and shake the bottle vigorously before opening.

It is a fact that all ions conduct differently.  The ion composition of your water sample should be the primary factor when selecting a calibration standard.  To ensure your instrument is calibrated accurately, a standard of similar ion composition to the solution being tested should be used.  If the predominate ion in a solution to be tested is NaCl (seawater, brackish water, etc.) the correct choice for a calibration standard is NaCl.  The three values on the bottle represent a cross-reference of the predominate ion composition of the three most common solutions tested.  These cross-reference values are correct at 25°C only.

442™ Natural water - this standard solution was developed by the Myron L^® Company to simulate the properties of natural water (rivers, lakes, wells, etc.).  The acronym 442 represents (4) 40% Sodium Bicarbonate, (4) 40% Sodium Sulfate, (2) 20% Sodium Chloride. The 442 standard is the best choice to use when measuring water samples such as city water, rivers, lakes, and wells.

NaCl - this standard solution is made of Sodium Chloride and is to be used to calibrate an instrument that measures solutions such as seawater and brackish water where predominate ions are NaCl (sodium chloride).

KCI Standard - this standard solution is made from Potassium Chloride and is an international standard to calibrate instruments that measure conductivity.  The unit of measure for KCl is micromhos/microsiemens or millimhos/millisiemens.

To choose the proper standard contact your Myron L^® distributor.

The most common error comes from not removing the rubber plug. Rinse the cell well and pour the sample to be measured into both wells.

By checking the download center on the website, you can access all of the part numbers and prices instantly.

Please see the instructions in your manual or download instructions from our download section of the website.

The Ultrameter II 6P must be switched to the resistivity parameter. First, you want to ensure that the pH cap is secure and will not allow contamination from the pH sensor well. Hold the instrument down at a 30˚ angle allowing the sample to flow over the cell cup and down away from the user. Let the sample flow continuously into the conductivity cell. If sample is from a spout, bring unit as close to the spout as possible to avoid aeration and atmospheric contamination.

With everyday sampling, the cell cup may build up a residue or film on the cell walls that may cause the readings to become erratic. Use a 50/50 mixture of a common household cleaner (i.e. Lime-A-Way, CLR, Tilex, etc) and DI water. Pour into conductivity cell cup and scrub with a q-tip. Be sure to get around all the electrodes and the thermistor probe. On the DS handheld unit, use an acid brush to scrub the cell cup. Let it set for about 10 minutes. Rinse the cell cup thoroughly with tap water, then a final rinse with DI water.

Correlation between conductivity and TDS is non-linear. No single multiplier can be used to determine the relationship.

This is possibly caused by contamination to the circuit board. One or more of the traces on the PCB have been jumped/bridged and there is a contamination. Possible moisture, condensation, dirt, dried salts or other condensation inside is a potential cause for this display.

The more times the case is opened, it increases the chances of contamination or moisture in the case. The only time to change the battery is when the “LO BATT” symbol displays, when the units just simply wont turn on, or when the case is already open to change the pH probe. When moisture/debris get inside, it can cause a malfunction.

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.

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.

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.

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.

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.

This is caused when the 115/230 VAC switch is set to 230VAC when in fact it should be switched to 115 VAC.

The cell substitutes cannot be used for both Series. There are different part numbers for the 750 & 750 II Series.

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

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.

Our 750 Series II Conductivity/TDS and Resistivity Monitors and Monitor/Controllers can be “Re-Ranged” with a new range module to meet your 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.

The module number is circled on the transformer and printed on the back of the case.