15
MODEL 381pH/ORP SECTION 3.0
MAINTENANCE
SECTION 3.0MAINTENANCE3.1 GENERAL. This section provides instructions for
performing periodic maintenance and for determining
the cause of a malfunction (troubleshooting).
3.2 PERIODIC MAINTENANCE. The following period-
ic maintenance is based on operation in a water sam-
ple. Determine the schedule for the operation being
maintained from past experience, or by analyzing data
gathered since initial installation of the sensor.
3.2.1 Monthly. Perform the following maintenance
monthly:
1. Remove the sensor from the solution or sample
and observe the condition of the electrode tip.
2. If the electrode tip is coated, clean it with a soft,
clean cloth or tissue moistened with a mild, non-
abrasive detergent, and rinse the electrode tip with
clean water. Detergents may be used to remove
oil and grease coatings.
3. If Step 2 does not clean the electrode tip, remove
the electrode and clean it with a dilute, 0.1
hydrochloric acid solution and rinse with clean
water. HCI may be used to remove thin film and
scale coatings not removed with a damp cloth or
detergents.
4. Check calibration and install the sensor in the
process as instructed in Section 2.0.
3.2.2 Annually. Perform the following maintenance
annually (not required for combination electrode):
1. Remove the sensor from the process.
2. While holding the sensor in an upright position,
remove and discard the liquid junction.
3. Drain the solution from the sensor body and rinse
the inside of the body with clean, warm water.
4. Remove the cover from the body by grasping the
body and rotating the cover ΒΌ-turn in the counter-
clockwise direction.
5. When the cover breaks loose from the body, pull
straight out on the cover and disconnect the cable
connector from the preamplifier.
6. Disconnect the electrode BNC connector from the
preamplifier and then unplug the preamplifier from
the body.
7. Remove and discard the double junction elec-
trode.
8. Remove and discard the O-rings on the body.
9. Install a new double junction electrode in the body
(refer to Table 3-4 Spare Parts).
10. Make sure the upper and lower body O-ring seal-
ing surfaces are clean, and lubricate the new O-
rings with O-ring lubricant (P/N 2001928). Install
the O-rings making sure they are not twisted.
11. Install the preamplifier on the body and make sure
all connections are secure and that both O-rings
are in place.
12. Install the cover on the body so the threads will
engage.
13. Rotate the cover until the triangle on the body
aligns with (or falls within) the adjacent mark on
the cover.
CAUTION
DO NOT use a pipe wrench on the body or
cover. Severe damage could result.
14. While holding the sensor in an upright position, fill
the reference chamber in the body (through the
liquid junction opening) with gel solution (P/N
9210342). Care must be taken to remove as much
air as possible from the reference cell.
15. Wrap Teflon tape on a new liquid junction (see
Table 3-4 Spare Parts) and install the liquid junc-
tion in the body.
16. Test the sensor per Section 2.7. Install the sensor
as described in Section 2.0.
NOTE
Flow-through sensor (Codes 03 & 04). Upper
and lower flow cell O-rings should be
replaced at this time. Lubricate new O-
rings with O-ring lubricant (P/N 2001928)
and reinstall sensor as described in
Section 2.4. & 2.5.