Ph Electrode Cleaning; Platinum Electrode Cleaning - Emerson Rosemount 385+ -02 Reference Manual

Maintenance
February 2019
4.2.2 Insertion/Submersion Version (Code -03 and -04 )
WARNING
Before removing the sensor, be absolutely certain that the process pressure is reduced to 0 psig and
the process temperature is lowered to a safe level!
Remove the sensor from process for cleaning, calibration or replacement.
4.3

pH Electrode Cleaning

If the electrode is coated or dirty, it may be cleaned as follows:
1.
2.
3.
CAUTION
The solution used in the following step is an acid and should be handled with care. Follow the directions of the
acid manufacturer. Wear the proper protective equipment. Do not let the solution come in contact with skin
or clothing. If contact with the skin is made, immediately rinse with clean water.
4.
5.
4.4

Platinum Electrode Cleaning

Remove any film or dirt by wiping the electrodes platinum band with a clean, lint free, cloth. If
needed, a strong detergent should be used to remove any remaining dirt or film.
Platinum electrodes can become poisoned by cyanide or sulfide compounds. However, processes
involving these compounds (such as cyanide destruction) will destroy all the cyanides or sulfides
before they can react with the platinum.
Should poisoning occur, the electrode can be restored to normal operation by polishing the
platinum (metallic) surface with moistened baking soda (after a strong detergent wash to remove
any film on the platinum surface).
20
Remove the sensor from process as instructed in Section 4.2.
Wipe the glass bulb with a soft, clean, lint free cloth or tissue. If this does not remove the
dirt or coating, proceed to step 3. If the sensor appears to be clean, go to step 5.
Wash the glass bulb in a strong detergent solution and thoroughly rinse with tap water. If
the bulb still appears to have a coating, proceed to step 4.
Following the caution above, wash the glass bulb in dilute 5% hydrochloric acid solution
and then rinse it thoroughly in tap water. Replace the sensor if it cannot be cleaned. If the
glass bulb appears clean, proceed to step 5.
Buffer calibrate the sensor (Refer to Section 3.0). If the sensor appears to respond
sluggishly to pH change, soaking it overnight in a weak acid solution (5% hydrochloric acid)
may improve its response. Be sure to follow the CAUTION above and to rinse the sensor's
tip thoroughly with tap water. If the sensor will not calibrate, it must be replaced.
Reference Manual
00809-0100-3386
Maintenance