General Water Treatment F.A.Q.
Can I calibrate my MyronL resisivity in line monitor/controller using a standard ?
Why does the Myron L standard solutions show three different values on the bottle?
How long will my Myron L standards and buffers last?
Why does my pH always read 4.0?
What is pH?
Definition: The negative logarithm of hydrogen ions in a solution.
Ratio of Hydrogen ions (H+) and Hydroxyl ions (OH-) determine the pH value of a solution. Any hydrogen activity
will produce a 59.16 mV/pH unit across the glass membrane. The measurement is expressed on a scale of 0.0
to 14.0. Water with a pH of 7 is considered neutral (H+ ions = 10-7 and OH- ions =10-7). A solution is
considered Acidic when the hydrogen ions (H+) exceed the Hydroxyl ions (OH-) and a solution is considered an
Alkaline (base) when the Hydroxyl ions (OH-) exceed Hydrogen ions (H+).
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Can I calibrate my MyronL resisivity in line monitor/controller using a standard ?
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.
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Can I calibrate my Myron L hand held EP or Ultrameter in the resistivity range (0 to 18 megohm) using a liquid standard?
No, unlike the in line resistivity monitor/controller, the Myron L Ultrameter hand held instrument combines the unique ability to measure conductivity (0 to 200 mS) and resistivity (10KΩ to 30MΩ) 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.
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Why does the Myron L standard solutions show three different values on the bottle?
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. 442ú Natural water - this standard solution was developed to simulate the properties of natural water (rivers, lakes, wells, etc.). The acumen 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.
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How long will my Myron L standards and buffers last?
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.
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Why does my pH always read 4.0?
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.
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