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8.1.9
ORP Electrode Cleaning
8.1.10
Industrial pH Electrode Cleaning
8.2 Pump Maintenance
8.2.1 Changing Pump Tubing
Fouling of the platinum sensing element of the ORP electrode can cause sluggish response
and drift. To clean the electrode, soak it in 1N HCl for 15 minutes. Recalibrate before
replacing it in the sample.
Some process streams contain materials that adhere to the glass of the electrode.
Frequency of required cleaning is determined from experience with the sample stream
being tested. Loose or lodged debris can usually be removed by placing the electrode
under a flowing spigot or the jet of a wash bottle.
Wipe the glass membrane gently with a soft, wet cloth or a paper tissue. Never use
abrasive cleaners on the glass membrane. Remove oil deposits by cleaning in a solution of
liquid dishwashing detergent and warm water. Do not use ammonia or ammonia-
containing cleaning solutions. If necessary, use 1% HCl or other dilute acid solution to
clean the glass. Do not leave the electrode in the acid for more than 30 seconds. Always
wash the electrode thoroughly with a mild detergent after cleaning with acid, then rinse in
deionized water. After cleaning with an acid solution, allow the electrode to soak for an
hour in a neutral (pH 7.00) buffer solution
The plastic housing can be cleaned with almost any mild detergent.
Under ambient pressures and temperatures, the pump tubing should give at least 3 to 6
months of useful service. Though the rate of electrolyte dispensed decreases over time,
this is not critical. As long as some electrolyte is flowing, the reference junction should
remain cleared. Check for pump tubing failure by observing the reference outlet tube of
the electrode while the pump is running and the priming tee is in the RUN position.
A full drop of electrolyte should appear in less than 5 minutes (5 pumps).
If it does not appear, purge the system (see Section 8.1.6 Purging the System) to make sure
the reference line is not clogged. Replace the tubing if the reference line is clear (see
Figure 26 on page 89).
1. Cut a section of the replacement pump tubing (Part No. 43623-00) to 3.5 inches.
2. Remove the pulse dampener by disconnecting it from the pump tubing. Shake the fluid
out of the pulse dampener.
3. Disconnect the pump tubing at the inlet side.
4. Loosen the four plate screws over the pump face.
5. Pull out the old tubing and install the new tubing.
6. Reconnect the tubing and pulse dampener.
7. At this point, proceed as you would for purging the system (see Section 8.1.6 Purging
the System).
87
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Troubleshooting
