Chlorine Gas & Chlorine Water
Where even "universal" fluoropolymers and standard elastomers fail — including at disinfection-residual concentration, not just industrial strength.
Chlorine gas and chlorine water attack more materials than specifiers expect. Wet chlorine gas fails both common elastomers, FKM and EPDM, at room temperature, leaving only true fluoropolymers viable. PFA, normally a broad default, fails even against a dilute 400 ppm chlorine-water disinfection residual of the kind found in routine treatment-plant service.
Chlorine: identifiers
| CAS Registry Number | 7782-50-5 |
|---|---|
| Molecular formula | Cl2 (Hill notation) |
| Molecular weight | 70.90 g/mol |
| PubChem record | CID 24526: Chlorine |
Two Real Conditions, Two Different Failure Sets
Wet chlorine gas (5%)
HDPE and PP both fail even at 68°F room temperature. FKM and EPDM — both common elastomers — also fail outright at any temperature tested. Only PVDF, ECTFE, PTFE, FEP, and PFA remain resistant.
Chlorine water (400 ppm, typical disinfection residual)
PVC/CPVC resistant-to-conditional through 104-140°F. FKM fails even at 68°F. PFA — normally considered a broadly chemical-resistant "universal" fluoropolymer — also fails even at 68°F. Two materials normally treated as safe defaults both fail against even a dilute chlorine-water residual.
Source: combined chemical resistance chart, 858 real data rows. Confirm current ratings with the manufacturer before final specification.
Real Chlorine-Service Valve Data
AVCO Valve's Chlorine Service Ball Valve line is built specifically to Chlorine Institute Pamphlet 6 compliance — carbon steel body with Monel 400 or Hastelloy C wetted trim, and a vented ball for pressure relief. This is chemistry-specific engineering data for gas-phase chlorine handling, distinct from the material compatibility findings above which cover wetted plastic/elastomer components.
Frequently Asked Questions
Can standard elastomers handle wet chlorine gas?
No — FKM and EPDM, the two most common elastomer choices, both fail outright against wet chlorine gas even at room temperature. Only true fluoropolymer materials (PVDF, ECTFE, PTFE, FEP, PFA) remain resistant.
Is PFA always safe to assume for chlorine service?
No — this is a genuinely counterintuitive finding. PFA, normally treated as a broadly chemical-resistant "universal" fluoropolymer, fails even at 68°F against chlorine water at just 400 ppm — a typical treatment-plant disinfection residual concentration, not an aggressive industrial concentration. Never assume PFA compatibility for chlorine service without confirming the specific rating.
Why does a low chlorine concentration (400 ppm) still cause material failures?
Chlorine water at disinfection-residual concentration is chemically distinct from a simple dilution assumption — both FKM and PFA fail at this concentration despite it being far more dilute than industrial chlorine gas handling. Concentration alone doesn't predict material compatibility; the specific chemical form (gas vs. dissolved water) and material combination both matter.
What real chlorine service data exists for valves?
AVCO Valve's Chlorine Service Ball Valve line is built to Chlorine Institute Pamphlet 6 compliance, with carbon steel body and Monel 400 or Hastelloy C wetted trim, plus a vented ball for pressure relief — real, chemistry-specific engineering data for gas-phase chlorine service distinct from the material compatibility data above.
Confirm your exact chlorine service before you specify
Send LibertyCES your chlorine form (gas or dissolved), concentration, and temperature — we'll confirm the right material.
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Reviewed by James Riggins, 30+ years specifying water and chemical process equipment · Updated