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Chemical Compatibility

Controller — Acids

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Named chemicals

Sulfuric Acid (chrome reduction/cyanide destruction stage 2)

What LibertyCES's vendor documentation shows

Chrome reduction: pH lowered to 2.0-2.5 via acid dosing, ORP setpoint -300mV, explicit SO2 gas-release hazard if overdosed.

Materials documented for this service

  • N/A

Products cited for this service

GF Signet controller

Real Specifications

Chrome reduction optimum pH rangepH 2.0-2.5gf-signet-application-solutions.md
Chrome reduction minimum detention time15 minutesgf-signet-application-solutions.md
Chrome reduction ORP setpoint-300mV (-400mV max)gf-signet-application-solutions.md
Cyanide destruction stage 2 (sulfuric acid) detention timeUp to 4 hours (modern systems)gf-signet-application-solutions.md
Cyanide destruction stage 1 oxidation targetBelow 0.1 ppmgf-signet-application-solutions.md
Install / Failure Note

GF Signet warns explicitly that lowering pH further than the 2.0-2.5 optimum on chrome reduction risks releasing hazardous sulfur dioxide gas — the reaction only needs to reach pH 3.0 before it slows significantly, so overshooting low doesn't buy faster reduction, it buys a gas hazard.

Chrome reduction is regulatorily strict for a reason — hexavalent chromium is roughly a thousand times more toxic than trivalent chromium per GF Signet's own literature, and it won't form a settleable hydroxide precipitate until it's reduced. Getting the pH/ORP control loop right (2.0-2.5 pH, -300mV ORP, 15-minute minimum detention) is the difference between a compliant discharge and a violation, which is why Liberty CES treats this controller spec as safety-critical rather than a tuning nicety.

Every material and product claim on this page traces to real, vendor-published documentation on file with LibertyCES. Chemical compatibility depends on exact concentration, temperature, and duty cycle — confirm current specifications with the manufacturer and request a spec review before final specification.

FAQ

Is Controller compatible with Acids?

Chrome reduction: pH lowered to 2.0-2.5 via acid dosing, ORP setpoint -300mV, explicit SO2 gas-release hazard if overdosed. This is strong evidence.

What materials are documented for Controller in Acids service?

Materials documented for this service: N/A. Chemical compatibility depends on exact concentration, temperature, and duty cycle — confirm with a spec review before final specification.

What specific Acids chemicals does this cover?

Named chemicals in this documentation: Sulfuric Acid (chrome reduction/cyanide destruction stage 2).

What products are cited for Controller in Acids service?

Documented examples include GF Signet controller.

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