Note: Refer to TDS/Conductivity Equivalents chart for actual calibration point values.

Note: RE-10 Range Extenders are usually calibrated with either 442-15,000 or 442- 30,000 Standard Solution.

Conductivity instruments are a convenient way to determine the parts per million of total dissolved solids (ppm/TDS) in boilers, cooling towers, reverse osmosis systems, etc. Although the International Unit (Sl) of measuring conductivity is the microsiemens/ cm (also known as micromhos/cm), a direct reading in ppm/TDS is sometimes preferred.

Myron L^® conductivity instruments and monitor/ controllers are calibrated to read in ppm/442, ppm/ NaCI, or microsiemens. All three values are listed on our Standard Solutions. The relationship among these standards can be seen in the table and graphs that follow.

442 Natural Water™ Standard Solution is used in calibrating many Myron L^® Instruments. It is the best choice when measuring boiler and cooling water samples, city water supply, lakes, wells, etc. "442" refers to the combination of salts mixed with deionized water to comprise this standard: 40% sodium sulfate, 40% sodium bicarbonate, 20% sodium chloride. A combination of standard salts is necessary since natural water salt type and concentration can vary greatly by location. After much research, the 442 Standard was developed by the Myron L^® Company more than 40 years ago. It remains the world's most accepted standard.

NaCl Standard Solution is offered to calibrate instruments that measure any sample that is predominately NaCI (sodium chloride), such as sea water, brackish water, etc. As can be seen in the graph at right, 1000 ppm of NaCI has a conductivity of 2000 micromhos. Note how this 1:2 relationship is continuously variable throughout the curve and decreases as ppm NaCI increases.

KCl Standard Solution is used to calibrate conductivity instruments that read directly in microsiemens (micromhos) or millisiemens (1000 microsiemens). KCI (potassium chloride) is a very stable salt and is an international calibration standard for conductivity measurement.

pH Buffer Solutions 4, 7 and 10 are mold inhibited and accurate to within + 0.01 pH units @ 25°C. Myron L^® Buffers are traceable to NIST certified pH references and are color-coded for instant identification.