CR O-Rings (Neoprene / Chloroprene)

Chloroprene Rubber (CR), also known as neoprene rubber and widely searched as chloroprene o rings, is a versatile synthetic elastomer that bridges the gap between general-purpose and specialty sealing materials. CR offers good resistance to weathering, ozone, and refrigeration gases, combined with moderate oil resistance and inherent flame retardance.

With an operating temperature range of -40°C to +120°C, CR is commonly used in HVAC systems, marine deck hardware, and outdoor applications where ozone degradation would rapidly destroy standard NBR. CR remains compatible with common refrigerants including CFC, HCFC (R-22), and ammonia (R-717). For newer HFC refrigerants (R-410A, R-32, R-134a), verify compound compatibility — some modern CR formulations perform well, but testing at actual service conditions is recommended.

CR also exhibits excellent adhesion to metal substrates, making it a preferred material for bonded sealing assemblies, hose liners, and fabric-reinforced gaskets.

CR swells significantly in aromatic fuels, ketones (MEK, acetone), and strongly oxidising acids. For petroleum applications with aromatic content, NBR or FKM are the better choices. For weather and ozone resistance combined with oil resistance, HNBR is a technically superior but higher-cost option.

Lead time: 7–15 days standard; 3–5 days for stocked sizes. MOQ: 1 piece. ISO 9001 certified.

The molecular structure of CR is poly(2-chloro-1,3-butadiene), polymerized primarily in the trans-1,4 configuration (approximately 85–90%) with minor cis-1,4 and 1,2-vinyl content. The chlorine atom (approximately 40% by weight) attached to every other carbon in the backbone provides three key benefits: it increases polarity, giving CR moderate oil and fuel resistance superior to EPDM; it improves flame resistance by releasing HCl gas during combustion, which dilutes oxygen and suppresses flame propagation (UL 94 V-2 rating); and it provides some degree of ozone resistance by reducing the reactivity of residual double bonds. CR is vulcanized using metal oxides — zinc oxide (ZnO) and magnesium oxide (MgO) — rather than sulfur, forming ether crosslinks (-C-O-C-) that are more thermally stable than polysulfidic bonds. The presence of residual double bonds (unlike fully saturated HNBR or EPDM) means CR is not completely ozone-proof, but it resists ozone cracking far better than NBR.

Quantified performance comparisons versus related elastomers clarify CR's niche. In ozone resistance (ASTM D1171, 50 pphm, 40°C, 20% strain), CR shows no cracking after 200–400 hours, while NBR fails within 24–48 hours — a 5–10× improvement. EPDM and HNBR still outperform CR, showing no cracking after 1000+ hours. In oil resistance (ASTM D471, IRM 903 at 100°C, 70 h), CR shows volume swell of 20–40% versus NBR's 10–20% and HNBR's 5–15% — CR is less oil-resistant than NBR but more resistant than EPDM (>40% swell). In flame resistance (UL 94), CR achieves V-2 self-extinguishing rating while NBR, EPDM, and VMQ burn readily — only FKM (V-0) and specialty flame-retardant compounds outperform CR. In adhesion to metal, CR's polarity and metal oxide cure system provide bond strengths of 4–8 MPa in standard peel tests, significantly higher than NBR's 2–4 MPa — making CR the preferred choice for bonded metal-rubber assemblies. In low-temperature flexibility (TR10, ASTM D1329), CR achieves -35°C to -40°C, comparable to NBR but inferior to EPDM's -45°C to -50°C.

A practical selection decision tree: if your application is an HVAC compressor seal handling R-22, R-717 (ammonia), or legacy CFC refrigerants, specify 60–70 Shore A CR — it is the historical industry standard and remains cost-effective. If your application is marine deck hardware exposed to salt spray, UV, and ozone, specify 70 Shore A CR with UV stabilizer; for the highest durability in this environment, HNBR is the technical upgrade at 3× cost. If your application requires flame-retardant sealing in mining equipment or transportation, specify CR with flame-retardant additive package (UL 94 V-2) — it is the most economical self-extinguishing elastomer for general industrial use. If your application is a bonded metal-rubber seal assembly, specify CR for its superior metal adhesion. If your application involves modern HFC refrigerants (R-410A, R-134a), request ASTM D471 immersion data for the specific refrigerant and lubricant combination before specifying CR — compatibility is formulation-dependent. If your application involves aromatic fuels, ketones, or concentrated acids, do not use CR — specify NBR, FKM, or FFKM. If continuous service above +120°C is required, specify HNBR or FKM.

Storage of CR O-rings is straightforward but requires attention to the metal oxide cure system. Store in opaque packaging below 25°C, away from strong acids that could neutralize the MgO/ZnO cure system and cause scorch or premature curing. CR is resistant to moderate ozone levels but should still be kept away from high-ozone sources. The recommended shelf life is 5–7 years under ideal conditions. CR's specific gravity of 1.20–1.35 provides easy field distinction from NBR (1.00–1.25) and EPDM (0.86–0.87). A common error is specifying CR for modern automotive refrigerant systems using R-1234yf (HFO) with PAG oil — some CR compounds show excessive swell in PAG lubricants, and HNBR or specific HFO-compatible CR formulations should be verified before use. Another frequent mistake is confusing CR with NBR in inventory: both are black, and hardness ranges overlap. Specific gravity measurement (CR 1.20–1.35 vs NBR 1.00–1.25) is the fastest field test; CR feels noticeably heavier than NBR of the same size.