Myron L 729II - Manual (Page 55)

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5. TRANSFER STANDARD METHOD
Another method of calibrating a Monitor/controller is via the
transfer standard. Instead of removing the entire Monitor/
controller and sensor, and either returning it to the manufacture or
sending it to a third party laboratory for recertification, the
transfer standard allows for a quick check and return to service
— less down time. It is very easy to perform, and may be used to
check ANY manufactures Monitor/controller — pH or ORP. This
method still has the benefit of third party verification, if so
desired. This method works very well with an ORP
Monitor/controller as span drift is usually not common in quality
sensors. However, it does have its limitations, especially in a pH
Monitor/controller, and can not be used if the controller is
expected to operate in wide range. It is recommended that the
internal electronic calibration be performed first.
NOTE: The recommendations below may not be applicable for all
applications or conditions - may require experimentation for best
results.
1. A high quality hand-held instrument, one capable of
accurate “pH” and/or “ORP” readings, such as the
Myron L Ultrameter II™ 6P or the TechPro II™ TPH1
or TH1, is calibrated using pH buffer solutions (4, 7 &
10), or if so desired, sent to a third party laboratory for
calibration & certification.
2. Once the Ultrameter II or TechPro II is calibrated, the
process solution is measured and recorded.
3. The Monitor/controller is than calibrated/adjusted to
match the value measured by the Ultrameter.
pH Monitor/controller
a. If the normal operating range of the is between 5 - 9
adjust the ZERO calibration control.
b. If the normal operating range of the is between 0 - 5 or
9-14 adjust the SPAN calibration control.
ORP Monitor/controller. ORP solutions of high ionic strength
and with a strong mV reading give the best results.
a. Adjust only the ZERO calibration control.
4. Turn power OFF.
5. Re-install front panel as described below in
“REASSEMBLY”.
REASSEMBLY
1. Carefully reinstall the front panel, bottom first.
Ensure no wires have been pinched between
enclosure and front panel.
2. Reinstall the screws and tighten.
3. To operate, turn power ON.
D. PREVENTIVE CARE
The Myron L Company recommends that the following Preventive
Care procedures be observed.
1. ENCLOSURE
1. Try to prevent exposure to excessive heat and moisture.
2. The Monitor’s main AC power source should be protected
against excessive voltage “spikes.”
3. Take care not to damage the Monitor/controller during
handling.
NOTE: Daily, weekly or monthly maintenance schedules are
based upon the frequency of use and the severity of the
Monitor/controller’s environment and operating conditions.
4. Repeat the Monitor/controller’s Check-Out procedures
to verify satisfactory operation and/or isolate possible
troubleshooting symptoms.
5. Check all cable connections to ensure that they are free
of moisture and contamination.
6. Inspect and replace damaged component boards and
cable assemblies.
CLEANING - clean front panel with limited soap and water, and
soft non- abrasive cloth. Dry.
2. pH and ORP SENSORS
Periodically remove, clean and inspect the sensor. pH and ORP
sensors may be cleaned using Isopropyl Alcohol (IPA). This will
remove oils that have saturated into the glass bulb and on the
surface of the reference junction.
If the process will not allow sufficient down time, replace sensor
with another, and clean using the procedure below. Periodic
cycling of sensors may be necessary due to the process.
Another effective, but less friendly method is to use 5% HCl
acid. This is harsh on the sensor and can be dangerous to
personnel. And it is usually not necessary unless there is excess
scaling.
Depending on application, soaking in enzymes is also an
effective method to clean the sensor.
Try the IPA first.
For ORP sensors we have found, after IPA cleaning, lightly
polishing the Platinum tip with emery paper will help to restore
the correct indication on the Monitor/controller. Allow recovery
time.
Clean using the following procedure.
1. Turn system OFF.
2. Carefully remove sensor from solution stream.
3. Rinse with clean water.
4. Shake dry.
5. Pour a small amount of IPA in to a beaker, glass, or cup.
6. Swish the sensor in the IPA for about 5 minutes.
7. Rinse again with clean water.
8. Shake dry.
9. Soak sensor in Myron L pH/ORP Storage Solution until
sensor recovers from IPA cleaning shock.
10. Reinstall sensor in to system line with fresh thread
sealant.
11. Turn system ON.
PLEASE NOTE THE FOLLOWING:
ALL pH and ORP sensors have a limited life.
Operating conditions; temperatures and solutions all have an
effect on that life. The higher the temperatures and stronger the
solutions, the shorter the life.
When not in use or in storage, sensors must be hydrated at all
times with pH/ORP storage solution.
Offset and drift characteristics may be compensated for by
Monitor/controller calibration, ZERO and SPAN respectively.
However, calibration beyond ±~1 pH unit or ±~60mV indicate
sensor contamination or damage, sensor must be cleaned or
replaced. Continued use beyond these limits could effect your
systems accuracy and reliability.