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8.1.5 Crystal Formation in Reference Tube
8.1.6 Purging the System
Note: If air bubbles are
detected, re-purge
the system.
8.1.7 Storage and Conditioning
8.1.7.1
pH Electrode Storage and Conditioning
8.1.7.2
ORP Electrode Storage and Conditioning
The electrolyte solution for the reference portion of the electrode contains 1.5N KCl in
40% glycerol in water solution. Should some portion of the electrode dry out, crystals
may interfere with the free flow of electrolyte. These deposits are easily removed by
disassembling the check valve (see Figure 25 on page 85) and immersing the entire
electrode and tube in hot water (approximately 45 °C/100 °F) for three to five minutes.
After the blocked areas are immersed for several minutes, reassemble the electrode. Take
the syringe full of electrolyte and attach it to the priming tee. Turn the priming tee handle
to the purge position (see Figure 21 on page 73). Push out several milliliters of electrolyte,
and reconnect the electrode to the pump. Turn the priming tee handle to the run position
(see Figure 21 on page 73).
1. Remove the storage cap from the electrode.
2. Loosen the four screws on the face of the pump to allow fluid to flow through the
pump tubing.
3. Connect the syringe (with the plunger all the way in) to the side port of the
priming tee.
4. Turn the priming tee handle to the FILL position (see Figure 21 on page 73 [Fill]).
5. Withdraw about 3 mL of electrolyte. Expel about 0.5 mL of electrolyte to clear any
trapped air bubbles in the tee. Turn the priming tee handle to the PURGE position (see
Figure 21 on page 73 [Purge]). With the syringe still attached, tighten the four pump
head screws. Be sure the tube through the pump runs straight across the fingers, and is
not pinched closed.
6. Purge all the air from the electrode line by holding the electrode up-side-down and
pushing electrolyte through with the syringe (see Figure 21 on page 73 [Purge]) Do
not push air back into the system. Turn the priming tee handle to the RUN position
(see Figure 21 on page 73 [Run]).
7. Disconnect the syringe.
8. Turn the pump on and look for fluid flow out of the electrode.
9. Reset electrolyte time (see Section 2.2.7 Reference Solution Timer).
For best results, attach the pH sensor and condition for at least one hour in buffer or
sample with the reference electrolyte pump on. Recalibration after the first day of use is
recommended. If the electrode is taken out of use and stored, flush the reference line with
deionized water using the syringe and luer lock adapter. Using the syringe, blow out the
deionized water with air. Store the electrode wet in reference electrolyte.
Attach the sensor and clean the electrode in 1M HCl for 15 minutes before use.
Recalibration after the first day of use is recommended. If the electrode is taken out of use
and stored, flush the reference line with a syringe filled with deionized water. Blow out the
deionized water with air using the same syringe. Store the electrode wet in
reference electrolyte.
84
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Troubleshooting
