Myron L Aquaswitch II - Manual (Page 40)

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CAUTION - READ FOLLOWING CAREFULLY
D . CALIBRATION PROCEDURES
AQUASWITCH I does not require calibration.
All Myron L AQUASWITCH II Monitor/controllers are factory
calibrated prior to shipping and are ready to install without further
calibration. Calibration should be checked occasionally with the
internal Calibration/Full Scale Test switch (FS SW) to ensure
continued accuracy. The following procedures are provided in the
event that recalibration becomes necessary. The only equipment
required are a tweaker or small screwdriver, and standard
solution.
Refer to Figure V.A.1. to locate the components described in this
section.
NOTE: When opening instrument, remove front cover with care;
a ribbon cable connects the front panel and main board.
When performing calibration procedures, the
technician must take extreme care to avoid
contacting the circuitry other than the CALibration
control. Failure to do so could result in damage to
the equipment, property and/or personal injury.
1. ELECTRONIC CALIBRATION
(CIRCUIT ONLY)
This method is faster than the following method using standard
solution, but it does not include the sensor. Therefore, it should
be used only in applications where the chance of sensor
contamination or damage are slight.
NOTE: The D I S play calibration control has been s e t and
sealed prior to leaving the factory, and under normal conditions
will not require readjustment. This allows the customer to use the
panel meter/display to easily set the electronic Full Scale value. If
the D I S play calibration control has been adjusted it will be
necessary to, first, verify or adjust the Full Scale using a DVM as
described in “Full Scale Calibration” below, followed by adjusting
the D I S play calibration control to Full Scale on panel
meter/display.
a. Full Scale Calibration
1. Ensure power is OFF.
2. Using a standard slot screwdriver remove the two (2)
screws on the front panel.
3. Carefully wiggle the front panel to loosen the gasket and
pull gently toward you. Do not pull more than about 8
inches/20CM or you could damage the wiring harness.
4. Turn the front panel around so that the back side is
facing you and set aside.
5. Turn power ON.
6. Press and hold the Full Scale Test switch. The display
should indicate Full Scale for the particular range
selected, i.e. 0-50 ppm should indicate 50. If not, set to
Full Scale with the CALibration control.
NOTE: When setting digital models with a full scale of 2000
(1999), it is advisable to adjust Full Scale to 1990, otherwise an
overrange condition may occur.
7. Turn power O F F .
8. Re-install front panel as described below in
“REASSEMBLY” or continue.
9. To operate, turn power ON.
b. 0-10VDC Recorder Output Calibration
For output voltages other than 10VDC, substitute as required, i.e.
5.00VDC or 2.00VDC per Section II.F.2.
Requires a DVM set to DC Volts.
1. Ensure power is OFF.
2. Attach DVM to RECORDER output connection.
3. Turn power ON.
4. Press and hold the Full Scale Test switch (FS SW).
5. The DVM should indicate 10.00VDC.
6. If not, adjust CALibration control until DVM indicates
10.00VDC.
7. Verify the panel meter/display, it should indicate Full
Scale reading as shown on Range Module.
8. If not, adjust D I S play control until a full scale reading is
displayed. When setting digital models with a full scale of
2000 (1999), it is advisable to adjust Full Scale to 1990,
otherwise an overrange condition may occur.
9. Turn power OFF.
10. Re-install front panel as described below in
“REASSEMBLY” or continue.
11. To operate, turn power ON.
2. CALIBRATION USING
STANDARD SOLUTION
The best method of recalibrating your conductivity/TDS
AQUASWITCH II Monitor/controllers is with NIST traceable
Standard Solution (available from the Myron L Company).
Because it includes the sensor, the entire system is recalibrated.
NOTE: Since standard solution calibrations are NOT practicable
with Resistivity models, another means of verification or
calibration of resistivity models is to use the transfer standard
method, using a hand-held or portable instrument capable of
resistivity measurements, i.e. the Myron L Ultrameter™. See
section V.D.4 description.
The following procedure describes the easiest method for
standard solution calibration of your Conductivity/TDS
Monitor/controller.
1. Using a standard solution which is 60-90% of full scale
of the instrument, i.e. for 0-20 µS range use KCl-18,
rinse thoroughly and fill a clean glass beaker with the
standard solution.
2. Place sensor in the beaker of standard solution. The
level of standard solution must be high enough to cover
at least 1/2" above cross hole.
3. Slowly shake the sensor to remove air bubbles from
inside the sensor bore hole.
4. Allow 5-10 minutes for temperature to equilibrate. For the
quickest and the best results, both the sensor and
solution should be at the same temperature.
5. Turn power ON.
6. Read the display of the instrument. The display should
match the value and units of measure located on the
bottle of standard solution. If the reading is different,
adjust CALibration control on the main circuit board until
the reading matches the solution value. This will require
removal of the front panel. For removal, see section
V.D.1.a, 1-4.
7. After adjustment, turn power OFF.
8. Re-install front panel as described below in
“REASSEMBLY”.
9. To operate, turn power ON.
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