Ph Orp Electrode Poisoning Ion Selection

Direct answer: Signet's own published pH/ORP Electrode Application Matrix rates its general-purpose 2724-2726/2734-2736 electrode families only '**' (Compatible, the lowest non-excluded tier) against every one of these poisoning chemicals, while the Harsh Chemicals family (2764-2767) rates '*****' (Better) against the identical list. This is not a hard compatibility cutoff (general-purpose electrodes will technically function) but a real electrode-life/reliability distinction - continuous exposure to silver-ion-reactive or heavy-metal chemistries will foul or poison a general-purpose electrode's reference junction faster than the harsh-chemical-rated version. Directly relevant to any cyanide destruction (see cyanide-destruction-ph-orp-setpoints) or chrome reduction (see chrome-reduction-ph-orp-setpoints) system quote, since both processes generate exactly these poisoning ions in the monitored stream, and to any plating-bath wastewater treatment quote generally.

Confidence: confirmed

Applies when	ph electrode, orp electrode, ph sensor, cyanide destruction, chrome reduction, plating wastewater, heavy metals
Avoid	general purpose pH electrode, 2724-2726, 2734-2736 (Instrumentation)
Recommend instead	Georg Fischer (GF Signet) 2764-2767 or 2774-2777 'Harsh Chemicals' pH/ORP electrode family ()
Rationale	Signet's own published pH/ORP Electrode Application Matrix rates its general-purpose 2724-2726/2734-2736 electrode families only '' (Compatible, the lowest non-excluded tier) against every one of these poisoning chemicals, while the Harsh Chemicals family (2764-2767) rates '***' (Better) against the identical list. This is not a hard compatibility cutoff (general-purpose electrodes will technically function) but a real electrode-life/reliability distinction - continuous exposure to silver-ion-reactive or heavy-metal chemistries will foul or poison a general-purpose electrode's reference junction faster than the harsh-chemical-rated version. Directly relevant to any cyanide destruction (see cyanide-destruction-ph-orp-setpoints) or chrome reduction (see chrome-reduction-ph-orp-setpoints) system quote, since both processes generate exactly these poisoning ions in the monitored stream, and to any plating-bath wastewater treatment quote generally.
Confidence	confirmed
Source	vendor-sources/gf-signet-instrumentation-catalog.md

Applies when

ph electrode, orp electrode, ph sensor, cyanide destruction, chrome reduction, plating wastewater, heavy metals

Avoid

general purpose pH electrode, 2724-2726, 2734-2736 (Instrumentation)

Recommend instead

Georg Fischer (GF Signet) 2764-2767 or 2774-2777 'Harsh Chemicals' pH/ORP electrode family ()

Rationale

Signet's own published pH/ORP Electrode Application Matrix rates its general-purpose 2724-2726/2734-2736 electrode families only '**' (Compatible, the lowest non-excluded tier) against every one of these poisoning chemicals, while the Harsh Chemicals family (2764-2767) rates '*****' (Better) against the identical list. This is not a hard compatibility cutoff (general-purpose electrodes will technically function) but a real electrode-life/reliability distinction - continuous exposure to silver-ion-reactive or heavy-metal chemistries will foul or poison a general-purpose electrode's reference junction faster than the harsh-chemical-rated version. Directly relevant to any cyanide destruction (see cyanide-destruction-ph-orp-setpoints) or chrome reduction (see chrome-reduction-ph-orp-setpoints) system quote, since both processes generate exactly these poisoning ions in the monitored stream, and to any plating-bath wastewater treatment quote generally.

Confidence

confirmed

Source

vendor-sources/gf-signet-instrumentation-catalog.md

This is a general engineering rule derived from real field/case-study evidence, not a substitute for a project-specific specification review — confirm against your exact process conditions before ordering equipment.

Source: Liberty Chemical Equipment & Supply, Inc. (LibertyCES) — engineering data compiled from real vendor and field-verified sources. For a free spec review, call James Riggins at (559) 395-5500 or email james@libertyces.com / sales@libertyces.com. Website: libertyces.com.