Medical Rubber Components
Medical rubber applications span a wider compliance and performance range than almost any other sector: from commodity gaskets in hospital equipment housings to precision-molded platinum-cured silicone diaphragms in life-critical fluid management systems. The standards are not interchangeable, the cure systems are not equivalent, and the sterilization compatibility varies significantly across compounds. Getting these right at the specification stage prevents costly design revisions and regulatory delays.
Wayne Rubber manufactures custom rubber seals, gaskets, o-rings, and diaphragms for medical device, pharmaceutical processing, diagnostic, and laboratory equipment applications in Wixom, Michigan. Platinum-cured silicone, USP Class VI EPDM, and biocompatible elastomers are available with full documentation. Wayne Rubber supplies to medical equipment OEMs and Tier suppliers; implantable device applications are outside our scope.
Three Standards That Are Not the Same Thing
FDA 21 CFR 177.2600, USP Class VI, and ISO 10993 are frequently cited together in medical rubber specifications as if they are equivalent. They are not. Each tests for different properties, is required by different regulatory bodies in different contexts, and applies to different contact scenarios. Specifying the wrong standard (or assuming one implies the others) leads to specification gaps that create regulatory problems during FDA submission or CE marking.
Specifies the permitted ingredients and extraction limits for rubber articles in repeated contact with food. This is a food safety regulation, not a medical biocompatibility standard. A compound compliant with 21 CFR 177.2600 has been formulated from the FDA’s permitted ingredient list and meets the extraction limits for aqueous and fatty food contact. It does not mean the compound has been tested for cytotoxicity, sensitization, or systemic toxicity in human contact. FDA 21 CFR 177.2600 compliance is the minimum requirement for food-contact seals and is commonly cited for pharmaceutical manufacturing equipment that contacts product. It does not satisfy the biocompatibility requirements for medical devices that contact patients or biological fluids.
Published by the U.S. Pharmacopeia, a non-governmental standards body whose standards are referenced in FDA regulations for pharmaceutical and medical applications. USP Class VI testing involves three in-vivo animal tests: a systemic injection test (acute toxicity, 72 hours); an intracutaneous test (local tissue reaction, 72 hours); and an implantation test (long-term tissue reaction, 7 days). A material that passes all three is designated USP Class VI compliant. This designation indicates the material does not produce acute toxic, sensitizing, or tissue-reactive responses in these test protocols. USP Class VI is the standard specification for pharmaceutical manufacturing equipment seals and for non-implantable medical device components. It is the primary biocompatibility certification that pharmaceutical equipment buyers and medical device OEMs specify for seals in patient-adjacent but non-implantable applications.
The international standard series for biological evaluation of medical devices, required for FDA 510(k) clearance and CE marking submissions for medical devices that contact patients. ISO 10993 is a framework of 20+ individual standards covering cytotoxicity, sensitization, hemocompatibility, genotoxicity, carcinogenicity, reproductive toxicity, and other endpoints depending on the contact type (surface contact, blood contact, implant) and contact duration (limited, prolonged, permanent). ISO 10993 testing requirements are substantially more extensive than USP Class VI and are required when the rubber component contacts human tissue or blood directly. A USP Class VI certification does not substitute for ISO 10993 in an FDA submission for a medical device. ISO 10993-5 (cytotoxicity) and ISO 10993-10 (sensitization) are the most commonly required endpoints for non-implantable device seals.
Platinum Addition Cure vs. Peroxide Cure: Why It Matters for Medical Applications
Silicone rubber is the dominant elastomer in medical applications, and it can be cured by two systems that produce materially different compounds despite similar base polymer chemistry. Peroxide-cured silicone uses organic peroxide initiators to crosslink the polymer chains. The peroxide decomposition produces organic acid byproducts (primarily methyl acetate and acetone from DCP-cured compounds) that remain in the cured rubber as extractables. These byproducts require thorough post-curing at 200°C to drive them out of the compound before use. Residual extractables in inadequately post-cured peroxide silicone can cause cell toxicity in biocompatibility testing and can affect drug product purity in pharmaceutical contact applications.
Standard food-grade silicone and many industrial silicone compounds are peroxide-cured. The compound can be formulated to meet 21 CFR 177.2600 and USP Class VI, but the extractables profile requires careful post-cure management, and the resulting compound has higher extractable levels than platinum-cured alternatives.
Platinum addition-cured silicone (LSR and platinum-cured HCR) uses a platinum catalyst to facilitate a hydrosilylation addition reaction between the vinyl groups and silicon-hydride groups in the polymer. The reaction produces no byproduct molecules; the cure is purely additive. The result is a compound with dramatically lower extractables than peroxide-cured silicone, no residual organic acids, and better stability under repeated sterilization. Platinum-cured silicone is the standard for pharmaceutical manufacturing seals, medical device components, and any application where extractable level specifications are part of the product or process validation.
A caution specific to platinum-cured silicone: organotin compounds, sulfur, and many amine-based accelerators inhibit the platinum catalyst, preventing complete cure. Contact between platinum-cured silicone and sulfur-containing adhesives, amine-based release agents, or standard peroxide-cured rubber compounds before cure is complete will result in uncured tacky surfaces. This incompatibility must be managed during assembly and tooling if platinum-cured silicone is used alongside other elastomers in a manufacturing environment.
Sterilization Method Compatibility by Compound
Medical rubber components used in reusable devices or equipment must survive the sterilization modality used by the end user or facility. Different sterilization methods attack rubber through different mechanisms, and compounds that survive one modality may fail in another. This is a specification step that the engineer specifying the seal must address; the rubber compound supplier cannot assume which sterilization protocol will be used.
| Compound | Autoclave / Steam (134°C) | Gamma Irradiation (25-50 kGy) | Ethylene Oxide (EtO) | H2O2 Vapor (VHP) | Dry Heat (180°C) |
|---|---|---|---|---|---|
| Platinum Silicone | Excellent: standard for repeated steam cycles | Good: some property change at high dose | Excellent: compatible; residual monitoring required | Excellent: preferred for VHP-compatible devices | Excellent: good to 200°C dry heat |
| USP Class VI EPDM | Good: suitable for steam to 135°C | Fair: acceptable for single-use; repeated doses cause hardening | Good: generally compatible | Good: acceptable for most H2O2 vapor programs | Fair: acceptable to 150°C; not for repeated dry-heat cycling |
| USP Class VI NBR | Poor: steam attack; hardening and cracking | Good: acceptable for single-use | Good: generally compatible | Fair | Poor: limit 120°C; repeated cycling causes hardening |
| USP Class VI FKM | Fair: acceptable for limited steam cycles; not continuous | Good: generally stable | Good: compatible | Good | Excellent: best dry-heat resistance to 200°C |
| FFKM | Excellent: steam to 200°C; best steam resistance | Excellent | Excellent | Excellent | Excellent: to 300°C; highest temperature rating |
Medical Rubber Applications
- Diagnostic instrument seals: platinum silicone o-rings and gaskets for blood analyzers, centrifuges, and in-vitro diagnostic equipment housings requiring USP Class VI compliance and low extractables
- Surgical instrument seals: autoclave-compatible platinum silicone seals for reusable instrument sterilization pouches, containers, and wrapping systems
- Respiratory device diaphragms: platinum silicone diaphragms for ventilators, CPAP/BiPAP devices, and anesthesia machines where biocompatibility and repeated steam sterilization are required
- Infusion pump diaphragms: precision-molded platinum silicone for drug delivery pump dosing chambers requiring tight dimensional tolerances and low extractables
- Dental equipment seals: silicone and EPDM seals for dental handpiece sterilization trays, autoclave chamber seals, and waterline fittings
- Imaging equipment gaskets: EPDM and silicone housing gaskets for MRI, CT, and X-ray equipment where biocompatibility is required for patient-adjacent surfaces
- Bioreactor and fermentation vessel seals: platinum silicone or USP Class VI EPDM gaskets for fermentation vessels, chromatography columns, and buffer preparation tanks in biopharmaceutical manufacturing
- Aseptic filling line seals: platinum silicone diaphragms and o-rings for aseptic filling valves and pump heads in pharmaceutical manufacturing requiring SIP sterilization
- Lyophilizer (freeze dryer) seals: silicone chamber door gaskets and vacuum system o-rings for freeze-drying equipment; must survive repeated steam-in-place cycles and cryogenic product temperatures
- Process chromatography seals: USP Class VI EPDM or silicone seals for column fittings, manifolds, and pump heads in purification processes
- Autoclave and sterilizer door seals: EPDM or silicone inflatable seals for steam sterilizer door closing mechanisms in pharmaceutical manufacturing
- Cleanroom equipment seals: low-particle-generation platinum silicone gaskets for HEPA filter housings, cleanroom pass-throughs, and equipment penetrations
- Analytical instrument seals: low-extractable platinum silicone o-rings for HPLC, GC, and mass spectrometry instrument fittings where extractables would interfere with analytical results
- Pipette and liquid handling seals: silicone piston seals and diaphragms for automated liquid handling and pipetting stations requiring chemical resistance and low contamination
- Lab autoclave seals: EPDM and silicone door gaskets for benchtop and floor-standing laboratory autoclaves requiring repeated 134°C steam cycles
- Cell culture equipment seals: platinum silicone seals for bioreactor vessels, spinner flasks, and culture vessel fittings requiring cytotoxicity compliance
- Cryogenic storage seals: silicone seals for liquid nitrogen storage vessels and cryogenic sample containers where low-temperature flexibility to -65°F is required
- Microfluidic device components: precision-molded platinum silicone channel seals and interface gaskets for lab-on-chip and microfluidic diagnostic platforms
- Sterilization container seals: silicone and EPDM lid gaskets for reusable surgical instrument container systems; must pass multiple 134°C Prevac cycles without significant compression set
- Hospital bed and equipment gaskets: EPDM and neoprene housing seals for hospital beds, patient monitoring equipment, and treatment devices with surface disinfectant exposure
- Medical gas system seals: EPDM o-rings and seals for medical oxygen, nitrogen, and nitrous oxide pipeline connections and regulator assemblies; confirm compound compatibility with the specific gas
- Wound care device seals: platinum silicone seals for negative pressure wound therapy (NPWT) canister connections and dressing interfaces
- Endoscope reprocessing equipment: EPDM seals for automated endoscope reprocessors (AER) handling high-level disinfectant solutions including glutaraldehyde and ortho-phthalaldehyde
- IV and fluid therapy equipment: platinum silicone and EPDM gaskets for infusion bag port connectors, drip chambers, and IV line attachment fittings
Medical Rubber Products from Wayne Rubber
Medical-Grade Elastomers at Wayne Rubber
Request Medical-Grade Rubber Components from Wayne Rubber
Provide the application, required standard (USP Class VI, ISO 10993, or 21 CFR 177.2600), sterilization method, contact type (device housing, fluid contact, or patient-adjacent), and dimensional drawing. Wayne Rubber will confirm the compound and provide full documentation.