Hach EC1000 Instruction Manual page 97

Symptom Probable Cause
The response The electrode is fouled. The
is slow. sample coated the pH glass
bulb with a solid film.
The sample is cold and/or of
low ionic strength.
Long term drift in The electrode has insufficient
the pH reading. conditioning.
The reference electrolyte is
not flowing out of the
electrode.
No electrolyte flow. Pump tubing is pinched off.
The priming tee is in the
wrong position.
The reference electrolyte
bottle is empty.
Air in the reference line.
The pump tubing is worn out.
To verify, remove the priming
tee, and turn on the pump.
Within 5 minutes a drop of
electrolyte should form at the
end of the tube exiting
the pump.
The reference line is clogged
(evidenced by the inability to
force electrolyte out of the
electrode reference outlet
during purging).
The electrode is clogged.
Leaks in the reference line
(evidenced by puddles of wet
crystals in the pump
enclosure, at the electrode
reference inlet, or along the
Teflon reference tubing).
Excessive use of Pump plate screws not tight.
electrolyte.
* Note: The Industrial pH Electrode does not include an electrolyte pump, disregard symptoms associated with the electrolyte pump.
Table 16 pH Electrode Troubleshooting* (continued)
Corrective Action
Clean the pH glass bulb (see Section 8.1.8 pH Electrode Cleaning ).
Raise the temperature of the sample.
Condition a new or dry electrode for at least one hour in the process
sample. Perform a grab sample calibration after conditioning.
Verify that a full drop of reference electrolyte forms within 5 minutes at the
end of the reference outlet tube of the electrode. If this does not occur, refer
to the next Symptom: There is no electrolyte flow.
Be sure pump tubing runs straight across pump fingers and is not pinched
against the black pump body. (See Section 8.2.1 Changing Pump Tubing ).
Verify that the priming tee is in the RUN position ( Figure 21 on page 73).
Refill the electrolyte bottle with Process pH Reference Electrolyte (Cat. No.
24291-00). Purge the system (see Section 6.3 Purging the System ).
Purge the system (see Section 6.3 Purging the System ).
Replace the pump tubing (see Section 8.2.1 Changing Pump Tubing ). May
be required every three months.
Determine if the clog is in the electrode or the Teflon reference tubing by
disconnecting the compression nut and ferrule from the electrode
electrolyte inlet. Purge the system (see Section 6.3 Purging the System ). If
the clog is in the reference tubing, disconnect the priming tee and reference
tubing from the pump tubing, and soaking it in hot tap water. Blow the clog
free with a syringe. Replace the tubing if this does not work.
Unclog by attaching the syringe luer lock adapter, found in the maintenance
kit, to the reference inlet of the electrode. Fill the syringe with water, and
attach it to the adapter. Remove the reference outlet screw with a small
screw driver. (see Figure 25 on page 85) Apply pressure to the syringe until
water drips out of the reference tube outlet. If this does not free the clog,
soak the electrode in hot tap water overnight and repeat the above process.
If the clog remains, replace the electrode.
Tighten all fittings. If a leak occurs at a compression nut and ferrule fitting,
be sure the ferrule is correctly oriented (see Figure 25 on page 85,
Detail A ). Leaks also may indicate a clogged system.
Tighten screws securely to pump face.
(See Section 8.2.1 Changing Pump Tubing )
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