Metex 8760CLP Total Free Chlorine & pH Analyzer - Manual (Page 58)

AQUAMETRIX INC.
1-800-742-1413 www.aquamerix.com
58
If the sensor tests as still good, and the analyzer and wiring works with the model AM-659, but the
“+ERR” or over-scale still occur when the analyzer and sensor are hooked up and placed in service, then
the most likely cause is a ground loop short forming, not actually a pH sensor problem. Refer to the
model AM-659 user manual troubleshooting procedures to resolve this pH loop, plant site, interaction
problem.
The above symptoms cover most difficulties associated with pH sensors. The key to isolating problems
in the pH sensor or analyzer is being able to separate the two.
Restoring Electrode Response
Used electrodes which are mechanically intact but low efficiency or slow responding, can often be
restored to full response by one of the following procedures:
1) Scale deposits:
Dissolve the deposit by immersion of the electrode tip, overnight (or over weekend), in electrode
wash solution, P/N AM-A1100091, followed by rinse in tap water. Soak in electrode storage
solution, P/N AM-A1100090 for 1 to 2 hours.
Difficult cases: Repeat substituting gentle scale remover, P/N AM-A1100093, then 15 minute rinse.
2) Oil or grease films:
Wash electrode tip with detergent and water. If film is known to be soluble in a particular organic
solvent, wash with this solvent. Rinse electrode tip with tap water. Let sit in demin water, P/N AM-
A1100015, for 2 to 4 hours, followed by 2 to 4 hours in electrode storage solution, P/N AM-
A1100090.
Difficult cases: Repeat using wash in sodium hypochlorite (Javex Bleach) in water solution,
adjusted to pH 6.5 ± 0.5 using vinegar or acid.
3) Plugged or dry reference junction:
Remove the contaminant with one of the above procedures, then soak in electrode storage solution,
P/N AM-A1100090 for 24 hours to one week.
Difficult cases: Repeat but heat almost to boiling for ½ hour first, then soak in electrode storage
solution, P/N AM-A1100090 for 24 hours to one week.
4) Biological growths:
Wash electrode tip with detergent and water.
Difficult cases: Wash with Sodium hypochlorite (Javex Bleach) in water solution, adjusted to pH
6.5 ± 0.5 using vinegar or acid. Use rubber gloves, and wash until deposits fall off or turn white.
Rinse tip with tap water. Let sit in demin water, P/N AM-A1100015 for 2 to 4 hours, then 2 to 4
hours in electrode storage solution, P/N AM-A1100090.
5) Clean, but slow and with less than 85% efficiency:
Wash electrode tip with electrode renew solution, P/N AM-A1100092, for 15 minutes. Rinse
electrode tip using tap water for 15 minutes. Let sit in demin water, P/N AM-A1100015, for 2 to 4
hours, followed by 2 to 4 hours in electrode storage solution, P/N AM-A1100090.
NOTE: If none of the above procedures succeed in restoring electrode response, it is near the end of
the useful life of that sensor and should be replaced.