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FREQUENTLY ASKED

QUESTIONS & DEFINITIONS

Q.  Can I calibrate my Myron L resistivity in line monitor/controller using a standard?

A.  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.


Q.  Can I calibrate my Myron L hand held EP or Ultrameter in the resistivity range (0 to 18 megohm) using a liquid standard?

A.  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 (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.

Q.  How long will my Myron L standards and buffers last?

A.  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.

Q.  Why does the Myron L standard solutions show three different values on the bottle?

A.  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.

Q.  Why does my pH always read 4.0?

A.  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.   


DEFINITIONS
(Used in Myron L Data Sheets, Application Sheets and Instructions)

ACCURACY

Refers to how close the indication is to the absolutely correct value.  A 1% accuracy on a 0-500 ppm instrument is accurate to within 5 ppm or 1% of 500 = 5.

BLEED VALVE

A small valve to bleed off small amounts of water from a container vessel or bath.

BLOWDOWN

Removal of liquids or solids from a process/storage vessel or a line by the use of pressure.

CALIBRATE

Check or adjust the graduations of a quantitative measuring instrument.

CONDENSATE

Steam which rises and cools to a liquid.  When measuring condensate, liquid Must Be COOLED before putting it into cell cup of instrument.

CONDUCTIVITY

The ratio of the electric current density to the electric field in a material. Some materials such as metals, copper, silver, gold, platinum have very high conductivities but other materials such as plastic may have a very low conductivity.  Seawater contains a large quantity of dissolved salts therefore, has a high conductivity.  Deionized water (DI) has a low conductivity.

CONVERSION CHART

Must be used to convert a parts per million reading to micromho or vice versa because the ppm scales are non linear and the micromho scales are linear. Because of the curve, there is no set ratio so one must refer to the chart.

DEMINERALIZATION

Removal of mineral constituents from water.

DEIONIZATION

Removal of ionized minerals and salts from a solution by a two phase ion exchange procedure.

DI WATER

Deionized water.

DIALYSATE METER

Verifies the total concentration of ionized salts in dialysate solutions used in hemodialysis or kidney equipment.

EFFLUENT

Liquid that has passed through a processing operation.

ELECTRICAL RELAY

Employs a solenoid to provide mechanical action to move a varying number of electrical contacts back and forth or on and off.

HCl

Hydrochloric acid - used to clean scale, accumulations of salts or alkaline condition.

KCl

Potassium Chloride - salt used to prepare micromho/microsiemen standards.  If a cell has a range of 0-1000 KCl, it is the same as 0-1000 micromhos.

LINEAR METER

The deflection of the pointer is proportional to the quantity measured. Micromho scales are linear.

MEGOHM

1,000,000 ohms of resistivity.
MHOA unit of conductance.  The conductance of a conductor in mhos is the reciprocal of its resistance in ohms.  In reference to solutions it is the ability of a solution to conduct current from point A to point B.  Also can be measured in millimhos and micromhos.
MICROEquivalence of 10-6 or one millionth (1/1,000,000). Symbol - µ.

MILLI

Equivalence of 10-3 or one thousandth (1/1,000). Symbol - m.
NaClSodium Chloride, salt used to prepare dialysate solutions and some standards usually upon request only.
NaOHSodium Hydroxide - strong base, highly alkaline and highly corrosive.
NONLINEARPertaining to a response which is not directly or inversely proportional to a given variable.  Parts per million scales are nonlinear.
OHMA unit of resistance to electrical current and ohm is the reciprocal of mho/siemen.  Symbol - .

PARTS PER MILLION/
ppm

Concentration expressed as parts of a dissolved solid (salt, in our case) per million parts of pure water.  For example, 1000 ppm of NaCl means 1000 parts NaCl in 1,000,000 parts of pure water.  In very dilute aqueous solutions, ppm is approximately equal to 1 mg solute per 1 liter of solution.  Abbreviated ppm.
PARTS PER THOUSAND/
ppt
Concentration expressed as parts of a dissolved solid (salt, in our case) per thousand parts of pure water.  For example, 100 ppm of NaCl means 100 parts NaCl in 1,000 parts of pure water.  Abbreviated ppt.
pHA term used to describe the hydrogen-ion activity of a system; a solution of pH 0 to 7 is acid, pH of 7 is neutral, pH 7 to 14 is alkaline.  Our pDS Meters have scales of 2 to 12 pH.

PRODUCT WATER

Water that has completed a recycling process.
POTABLE WATERSuitable for drinking (US standard 500 ppm).
POTASSIUM CHLORIDESalt used to prepare micromho standards KCl.
REPEATABILITYSame reading each time for the same solution.
RESIN BEDTank filled with resins and water is forced through these resins and the resins latch onto the conductive ions or dissolved solids in the water.
RESISTIVITYThe opposition of a medium which opposes or reduces current flow.  Any substance which reduces or eliminates current flow, reciprocal of conductivity.

REVERSE OSMOSIS

A method of water treatment by forcing pure water to pass through membranes that will not pass sodium or chloride ions.
SCALEA buildup of mineral, salts on surfaces of boilers, cooling towers, swimming pools (any interior surface of water liners or containers).  Scale can build up in cell cup of instrument.  This will insulate the electrodes from the solution to be measured, so it must be free from scale.
SCALES (DIALS)A means of measuring by graduated marks.  Myron L Instruments use both linear and non-linear scales depending on the model instrument. Measurement can be read in ppm or mhos e.g. DS Meter may have a scale with 50 divisions for each ppm.  0-500 ppm scale has divisions for each 10 ppm. 0-5000 ppm scale has a division for each 100 ppm.
SALINITYAmount of salt in a solution.
SIEMENSSee MHO.  Also can be measured in millisiemens (mS) and microsiemens (µS).  Symbol - S
SODIUM CHLORIDESee NaCl (table salt) used to prepare some standards upon request.
SOLENOID VALVEA valve actuated by a solenoid for controlling the flow of gases or liquid in pipes.
TEMPERATURE COMPENSATIONA solution which has a certain conductivity at a specific temperature will, when heated, increase its conductivity.  When that same solution is cooled or chilled, it will decrease its conductivity.  Temperature compensation means the conductivity reading will automatically adjust to what that solution would have read at a standard temperature.  Our instruments are compensated to 25°C or 77°F.
TOTAL DISSOLVED SOLIDS/TDSThe total solids dissolved in a solution.  This is a measurement of all conductive ions in the solution.  Abbreviated TDS.
TRACKINGThe ability of an electronic circuit to indicate known values across its entire operating range when, a predetermined coinciding current is applied to it.

442™ SOLUTIONS

This is the Myron L Company standard of natural water.  40% sodium sulfate, 40% sodium bicarbonate, 20% sodium chloride.

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