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associated with the coating and clogging. Frequency of cleaning will depend on the process and application. The
following procedures are used to clean pH and ORP electrodes.
If possible, the electrode should be cleaned without removing it from the sensor body. However, if the electrode
must be removed, the o-rings must be inspected and re-lubricated.
5.2.4
H E
C
C
P
LECTRODE
ARTRIDGE
LEANING
Remove the sensor from the process and carefully wash the wetted end of the electrode cartridge in a mild
solution of detergent and water or with methyl alcohol. If the electrode response is not improved, soak the
electrode in 0.1 Molar HCl for 5 minutes. Remove and rinse the electrode with tap water and soak in 0.1 Molar
NaOH for 5 minutes.
Remove the electrode from the NaOH solution, rinse the electrode with copious amounts of tap water and soak
in a 4 pH buffer solution for 10 minutes. This should improve the response of the electrode. If not, replace the
electrode.
If the electrode must be left out of the process for an extended period of time, store it in a solution of water
saturated with KCl or a 4.0 pH buffer solution. ECD does not recommend the storage of electrodes in distilled or
deionized water.
5.3 C
H
F
C
(CHFC)
ONSTANT
EAD
LOW
ONTROLLER
The CHFC is designed to provide a constant flow to the Free Chlorine Sensor (FCS) independent of variations in
the sample pressure. Decreasing the sample flow to the FCS will lower the output of the FCS. In most clean
water applications the CHFC requires no maintenance. The vertical position of the central tube sets the Head
Pressure of the system. It is set for optimal flow but lower flow rates can be attained by adjusting its height.
On a monthly basis visually inspect the CHFC, the interconnecting tubing and the drain tubing for obstructions or
sediments that may reduce the flow. The CHFC and tubing can be easily disassembled and cleaned with soap
and water. Some dirty applications like Cooling Towers may require periodic cleaning due to sediments.
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