Emerson Rosemount 389, Reference Manual

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4 Maintenance
Rosemount ™ 389/389VP sensors require minimum maintenance. Keep the sensors clean
and free of debris and sediment at all times. The frequency of cleaning by wiping or
brushing with a soft cloth or brush is determined by the nature of the solution being
measured. Remove sensors from the process periodically and check them in buffer
solutions.
WARNING
PRESSURE AND TEMPERATURE
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!
If the sensor will not calibrate, refer to your transmitter reference manual for proper test
procedures. If you determine that the sensor has failed, discard and replace it.
4.1 Clean electrode
If the electrode is coated or dirty, clean as follows:
Procedure
1. Remove the sensor from process.
2. Remove the sensor from process as instructed in
Retractable version
3. Wipe the glass bulb with a soft, clean, lint free cloth or tissue. If this does not
remove the dirt or coating, go to Step 4 (detergents clean oil and grease; acids
remove scale.)
4. Wash the glass bulb in a strong detergent solution and rinse it in clean water. If this
does not clean the glass bulb, go to Step 5 .
WARNING
CORROSIVE SUBSTANCE
The solution used during the following step is an acid; handle 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 skin is made,
immediately rinse with clean water.
5. Wash the bulb in a dilute 5% hydrochloric acid solution and rinse with clean water.
Soaking the sensor overnight in the acid solution can improve cleaning action.
Replace the sensor if it cannot be cleaned.
6. Following the Warning above, wash the glass bult in dilute 5% hydrochloric acid
solution and then rinse it thoroughly with clean tap water. Replace the sensor if it
cannot be clean. If the glass bulb appears clean, proceed to
Step 7 .
7. Buffer calibrate the sensor.
Reference Manual Maintenance
00809-0100-3389 February 2019
Reference Manual 31