High Temperature / Heat Resistant Silicone O-Rings
Manufacturer & Custom Solutions
High Temperature / Heat Resistant Silicone O-Rings
High-temperature silicone O-rings from ZSR Silicone stay flexible at 250°C and handle short spikes to 300°C. Choose from VMQ, FVMQ or fiberglass-reinforced grades depending on your heat and chemical exposure.
FDA 21 CFR 177.2600
Rubber Articles Intended for Repeated Use
LFGB 30&31
EU Food Contact Materials
USP Class VI / ISO 10993
Biocompatibility of Medical Devices
RoHS / REACH
Environmental Compliance
UL 94
Flammability of Plastic Materials
Built to Your Exact Spec
Custom Silicone O-Rings Options
Every Silicone Grade, One Perfect Seal
Every O-ring starts with the right compound. Platinum-cured and peroxide-cured systems are available for all grades — we recommend platinum cure for food and medical contact.
| Grade | Hardness (Shore A) | Temperature | Compliance | Best For |
|---|---|---|---|---|
| Industrial VMQ | 30 – 80 | -60°C to +230°C | RoHS / REACH | General industrial sealing |
| FDA Food Grade | 30 – 70 | -60°C to +230°C | FDA 21 CFR 177.2600 | Food & beverage equipment |
| Medical Grade (Platinum) | 10 – 70 | -60°C to +230°C | USP Class VI | Medical devices & laboratory |
| High Temperature | 40 – 80 | up to +300°C | RoHS | Ovens, lighting, engine bays |
| Fluorosilicone (FVMQ) | 40 – 80 | -60°C to +200°C | RoHS | Fuel, oil & solvent exposure |
| LSR (Liquid Silicone) | 10 – 80 | -60°C to +230°C | FDA / medical grades | High-volume precision parts |
| Transparent / Clear | 30 – 70 | -60°C to +200°C | FDA options | Visual inspection points |
From 0.5 mm ID to Oversized Joint Rings
Size, cross-section and tolerance are fully custom. Send a drawing, a standard size number (e.g., AS568-214), or a physical sample — we handle the rest.
| Item | Range / Options |
|---|---|
| Size Range | ID 0.5 – 500 mm+; molded or vulcanized-joint for oversized IDs |
| Cross-Section | 0.5 – 10 mm; round (standard), square-cut, custom profile |
| Size Standards | AS568 · JIS B2401 · BS 1806 · DIN 3771 · ISO 3601 · ISO 6149 · AN6227 / AN6230 (see standards table below) |
| Tolerance | ISO 3302-1 class per size & process; ±0.05 mm on small molded rings |
| Custom Geometry | Non-standard ID / cross-section from your drawing or sample |
| Surface | Standard finish / PTFE-coated for low friction |
Any Color Your Brand or Assembly Needs
We color-match silicone compounds to Pantone or RAL references, including translucent and transparent grades for visual inspection points.
Your Brand, Built Into the Part
Branding, part numbers and batch traceability — molded in, engraved or printed, without compromising the seal.
Molded, Spliced or Coated — One Factory
Molding, splicing and finishing under one roof — we match the process to your volume, size and tolerance target.
| Process | How It Works | Best For |
|---|---|---|
| Compression Molding | Pre-formed silicone pressed and cured in a heated mold | Medium volumes, large cross-sections |
| LSR Injection Molding | Liquid silicone injected into closed molds | High volumes, tight tolerances |
| Vulcanized Joint (Spliced) | Extruded cord cut to length and vulcanized into a ring | Oversized IDs, low volumes, fast tooling |
| PTFE Coating | Low-friction coating applied to finished rings | Dynamic sealing, easy installation |
| Rapid Prototyping | Prototype tooling before production mold | Fit & function validation |
Related Silicone O-ring
| Image | Product | Type | Short Info | Action |
|---|---|---|---|---|
| BS 1806 Silicone O-rings | Standard & Size | British Standard inch-size silicone O-rings. Common in UK and Commonwealth industrial equipment. | View Details |
| DIN 3771 Silicone O-rings | Standard & Size | German metric standard O-rings for hydraulic and pneumatic sealing in European machinery. | View Details |
|
| Custom Molded Silicone O-rings | Standard & Size | Custom-shaped silicone O-rings molded to your exact drawing or sample. No standard size limitations. | View Details |
| AS568 Silicone O-rings | Standard & Size | Inch-size silicone O-rings that follow the AS568 standard. Widely used in North American machinery and hydraulic systems. | View Details |
| AN6227 Silicone O-rings | Standard & Size | Aerospace-standard O-rings with small cross-section. Used in aviation and military-grade sealing. | View Details |
| JIS B2401 Silicone O-Ring | Standard & Size | Japanese industrial standard O-rings commonly used in Asian-manufactured machinery and automotive equipment. | View Details |
| ISO 3601 Metric Silicone O-Rings | Standard & Size | Metric silicone O-rings manufactured to ISO 3601 dimensions. Fits international equipment groove standards. | View Details |
| ISO 6149 Metric Silicone O-Rings | Standard & Size | Metric O-rings designed for hydraulic and pneumatic fluid power sealing applications under ISO 6149 standards. | View Details |
| FDA Food Grade Silicone O-Rings | Grade | Food-safe silicone O-rings compliant with FDA regulations. Safe for repeated food contact. | View Details |
| Industrial Grade Silicone O-ring | Grade | General-purpose silicone O-rings for industrial sealing. Cost-effective with reliable performance. | View Details |
| Medical Grade Silicone O-ring | Grade | Biocompatible silicone O-rings for medical devices. Passes USP Class VI and supports sterilization. | View Details |
|
| High Temperature / Heat Resistant Silicone O-Rings | Special Function | Silicone O-rings that stay flexible at temperatures above 200°C. For ovens, engines and furnaces. | View Details |
| Oil-Resistant / Fuel-Resistant Silicone O-Rings | Special Function | Modified silicone O-rings that resist swelling in oils, fuels and petroleum-based fluids. | View Details |
 | VMQ Silicone O-Rings | Materials | Heat and cold-resistant silicone O-rings for food, medical, automotive, and industrial applications. | View Details |
| HCR / HTV / Solid Silicone Rubber O-rings | Materials | Durable solid silicone rubber O-rings made by compression molding. The standard choice for general sealing. | View Details |
| Fiberglass Reinforced Silicone O-rings | Materials | High-strength silicone O-rings reinforced with fiberglass fabric. Withstands extreme heat and pressure. | View Details |
| Liquid Silicone Rubber (LSR) O-rings | Materials | Injection-molded liquid silicone rubber O-rings with tight tolerances and clean surfaces. Ideal for high-volume production. | View Details |
| Platinum Cured Silicone O-rings | Materials | Ultra-clean silicone O-rings cured with platinum catalyst. Lower extractables for food and medical use. | View Details |
 | Fluorosilicone (FVMQ) O-rings | Materials | Fuel and oil-resistant silicone O-rings for aerospace, automotive and chemical applications. | View Details |
| Transparent / Clear Silicone O-rings | Color | See-through silicone O-rings for visual inspection and clean-looking medical or food equipment. | View Details |
| Custom Colors Silicone O-rings | Color | Silicone O-rings matched to your exact color sample or specification. | View Details |
What Is High Temperature / Heat Resistant Silicone?
High temperature silicone is silicone rubber that has been specially formulated to resist heat aging. All silicone handles heat better than most rubber materials, but high-temp grades add extra protection so the O-ring stays soft and seals reliably for years in hot conditions.
How Standard Silicone Reacts to Heat
Standard silicone rubber is already heat-resistant because of its silicon-oxygen backbone. Unlike carbon-based rubber (like NBR or EPDM), silicone does not melt or decompose easily. However, at temperatures above 200°C for long periods, standard silicone starts to:
How High-Temp Silicone Is Different
At ZSR, we make high-temp silicone by adding heat stabilizers to the compound. These are special additives that:
The result is an O-ring that lasts 2 to 5 times longer in hot conditions than standard silicone.
PVMQ — The Extreme Option
For the hottest applications, ZSR offers PVMQ (phenyl methyl vinyl silicone). In this material, some of the methyl groups in the polymer chain are replaced by phenyl groups. This change:
PVMQ is the material used in aerospace engine seals and satellite components. It costs more than standard VMQ, but it is the only choice when the temperature range is extreme at both ends.
Key Properties of High-Temp Silicone
High temperature silicone is simply silicone rubber with extra protection against heat aging. It is not a different material family — it is the same silicone you trust, made stronger for hot environments. Whether your equipment runs at 150°C all day or sees 300°C spikes during startup, ZSR has a heat-resistant grade that fits. Our engineering team can review your temperature profile and recommend the right compound, hardness, and size for your seal.
Temperature Rating Comparison
Not all silicone O-rings handle heat the same way. At ZSR Silicone Parts, we offer three heat-performance levels so you can match the material to your actual temperature needs.
Grade | Continuous Use | Short-Term Peak | Key Features |
|---|---|---|---|
Standard VMQ | -60°C to +200°C | Up to +230°C | Good for most industrial and automotive applications. Lowest cost. |
High-Temp VMQ | -60°C to +230°C | Up to +250°C | Enhanced heat stabilizers. Better resistance to long-term heat aging. |
PVMQ (Phenyl Silicone) | -70°C to +230°C | Up to +300°C | Phenyl groups replace some methyl groups. Best for extreme heat and cold. |
What "Continuous" vs "Short-Term" Means
Continuous:
The temperature the O-ring can handle 24 hours a day, 7 days a week, for its full service life without hardening or cracking.
Short-Term Peak:
The maximum temperature the O-ring can survive for minutes or hours during an overload, spike, or emergency condition. It will not fail immediately, but prolonged exposure at this level will shorten its life.
ZSR's Recommendation:
Important:
Temperature ratings assume the O-ring is in air or an inert environment. In oil, steam, or certain chemicals, the maximum temperature may be lower. Send ZSR your full operating conditions and we will confirm the right grade.
Hardness Selection for High Heat
At high temperatures, silicone rubber becomes softer. This means a 50 Shore A O-ring at room temperature might feel like 40 Shore A at 200°C. If the material gets too soft, it can squeeze out of the groove or lose its seal force. At ZSR, we help customers pick the right hardness for their heat level.
The Heat-Softening Rule
As a general guide, silicone loses about 1 to 2 Shore A points for every 10°C above 100°C. A 50 Shore A O-ring at 25°C will measure roughly:
ZSR's Hardness Recommendations by Temperature
Operating Temperature | Recommended Hardness | Why |
|---|---|---|
Up to 150°C | 40 – 70 Shore A | Standard range works fine. |
150°C to 200°C | 50 – 70 Shore A | Slightly harder to offset softening. |
200°C to 230°C | 60 – 80 Shore A | Firmer material resists extrusion better at high heat. |
Above 230°C (short-term) | 70 – 80 Shore A | Maximum hardness for spike conditions. |
Compression Set at High Temperature
Compression set is the biggest enemy of high-temp seals. It measures how much the O-ring stays flattened after being squeezed for a long time. At high temperatures, compression set gets worse. ZSR controls this by:
Special Note on PVMQ
PVMQ (phenyl silicone) handles both extreme heat and extreme cold better than standard VMQ. However, it is more expensive and harder to source. At ZSR, we stock PVMQ for aerospace and defense customers who need that wide temperature window.
Common High-Temp Applications
ZSR's high-temperature silicone O-rings are used wherever equipment gets hot and must keep running.
Industry | Application | Temperature Challenge |
|---|---|---|
Automotive | Turbocharger seals, exhaust manifold gaskets, EGR valve seals, under-hood sensors | Engine bays reach 150°C–200°C. Turbochargers see 250°C+ spikes. |
Aerospace | Engine seals, fuel system gaskets, cabin pressure seals, avionics cooling | Altitude changes plus heat. Needs -55°C cold start and +200°C+ running. |
Food Equipment | Oven door seals, steam kettle gaskets, commercial fryer covers, baking machine seals | Steam at 100°C–150°C. Oven doors see 200°C+ during cleaning cycles. |
Industrial Heating | Furnace door seals, kiln gaskets, heat press pads, molding machine seals | Constant exposure to 200°C–250°C. Needs long life without hardening. |
Lighting | LED heat sink seals, stage light gaskets, projector seals | LED drivers and high-power lamps generate 150°C–180°C. |
Electronics | Power supply seals, transformer gaskets, battery pack seals, server cooling | Compact electronics with poor airflow. Heat builds up to 150°C+. |
Plastics & Rubber Molding | Injection molding machine seals, extruder gaskets, hot runner seals | Direct contact with melted plastic at 200°C–300°C. |
Renewable Energy | Solar inverter seals, wind turbine brake seals, battery thermal management | Outdoor exposure plus internal heat from power conversion. |