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.
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.
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.
6. What is the part
number and price?
By checking the download
center on the website, you can access all of the part numbers and
7. How do I change the
Please see the
instructions in your manual or download instructions from our
download section of the website.
8. How do I measure DI
water with my handheld?
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.
9. How do I clean the
conductivity cell cup on the handheld units?
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.
10. What is the
conversion from conductivity to TDS?
conductivity and TDS is non-linear. No single multiplier can be used
to determine the relationship.
11. The display on my
Ultrameter II 6P reads "Error 1". What does that mean?
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.
12. The meter is
malfunctioning or not displaying properly, so I changed the battery.
Now it doesn't work.......What happened?
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.
13. 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
14. 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
15. 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
16. My device
connected to the Myron L® 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.
17. 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.
18. 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.
19. Can I use my cell
substitute to calibrate the 750 Series and 750II Series Monitors or
The cell substitutes
cannot be used for both Series. There are different part numbers for
the 750 & 750 II Series.
20. 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.
21. 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
22. 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
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.
23. 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.