User Guide

pH/ORP PROBE CHECK

The pH electrode and the reference electrode for both pH

and ORP can be automatically monitored through HI 504.

Setup items involved are I.13 (pH electrode impedance test

enable), I.14 (reference electrode impedance test enable),

I.15 (maximum reference electrode impedance) and I.04 (po-

tential matching pin enable).

A “pH electrode broken or leakage error” (error code: 10) is

generated whenever the pH electrode impedance is less than

approximately 1 MΩ. This error can be due to breakage of the

electrode glass or short circuits caused by moisture or dirt.

A “reference electrode broken or dirty or not immersed” error

(error code: 11) is generated whenever the reference elec-

trode impedance is greater than the value set in item I.15

(maximum reference electrode impedance range is 0.5 to

100.0 KΩ, default is 50.0 KΩ). This error can be due to

soiling of the reference electrode. It can occur also when

either the reference electrode or the matching pin are not

immersed in the solution. An automatic cleaning procedure

can be triggered by this error (see the “Alarm - Error configu-

ration” section for more details).

The pH electrode test is performed when the following condi-

tions are satisfied:

• the test has been enabled through the setup item I.13;

• the device is in one of the following modes: idle, last cali-

bration data scrolling, event log file scrolling;

• the device is not in hold mode;

• the device is configured to measure pH.

Note If an amplified electrode is used, the pH electrode test

must be disabled through the setup item I.13.

The reference electrode test is performed when the following

conditions are satisfied:

• the matching pin has been enabled through the setup

item I.04;

• the test has been enabled through the setup item I.14;

• the device is in one of the following modes: idle, last cali-

bration data scrolling, event log file scrolling;

• the device is not in hold mode.

Note When testing or calibrating the instrument through a

pH/ORP simulator like HI 931001 or HI 8427, tempo-

rarily set the items I.13 and I.04 to “OFF”.