Material

Silicone (VMQ)

Silicone rubber (VMQ — Vinyl Methyl Silicone) offers the widest usable temperature range of any common elastomer, from -60 °C to +200 °C in standard grades and up to +300 °C in specialty high-temperature formulations. Its unique silicon–oxygen backbone provides inherent resistance to ozone, UV, weathering and ageing, along with excellent electrical insulating properties and biocompatibility. Silicone is available in FDA 21 CFR 177.2600, USP Class VI, BfR and 3-A Sanitary compliant grades, making it the first choice for food-contact, medical-device and pharmaceutical sealing. It is primarily a static-sealing material — mechanical strength and dynamic wear resistance are comparatively low versus organic rubbers like NBR or FKM.

Silicone (VMQ) O-rings in a range of sizes.

Silicone O-rings, food- and medical-grade compounds.

Material Data Sheet

Temperature range

-60 °C to +200 °C (high-temp grades to +300 °C)

Hardness range

20–80 Shore A

Tensile strength

5–12 MPa (typically ~7 MPa)

Elongation at break

200–600 % (typically ~300 %)

Compression set

15–30 % (at 150 °C × 22 h)

Resists

Extreme temperature swings, ozone, UV, weathering, many dilute acids and alkalis, food and body fluids

Avoid with

Petroleum fuels and oils, concentrated acids, ketones, steam >150 °C, dynamic high-wear applications

Standards

ASTM D2000 (FC/FE/GE class), ISO 1629, ASTM D1418 (VMQ/PVMQ designation)

Approvals

FDA 21 CFR 177.2600, USP Class VI, BfR, 3-A Sanitary, NSF/ANSI 51 (compound dependent)

Silicone types

Understanding silicone rubber grades

Several silicone sub-types exist, each tailored to a specific service envelope. FITCO supplies all common grades and can recommend the best match for your application.

Designation	Full Name	Temp Range	Key Feature
VMQ	Vinyl Methyl Silicone	-60 to +200 °C	General-purpose, best cost-to-performance ratio
PVMQ	Phenyl Vinyl Methyl Silicone	-100 to +200 °C	Extended low-temperature flexibility (aerospace, cryogenic)
FVMQ	Fluorosilicone	-55 to +200 °C	Fuel and oil resistance added to silicone's temperature range
LSR	Liquid Silicone Rubber	-50 to +200 °C	Injection-moulded, high precision, ideal for high-volume medical parts

Advantages

Why choose silicone O-rings

Widest Temperature Range

Continuous service from -60 °C to +200 °C (PVMQ to -100 °C, specialty grades to +300 °C) — no other common elastomer matches this span, making silicone ideal for applications with extreme thermal cycling.

Food & Medical Compliance

Readily available in FDA 21 CFR 177.2600, USP Class VI, BfR, 3-A Sanitary and NSF/ANSI 51 grades — the default choice for food-contact, pharmaceutical, medical-device and potable-water seals.

Weather, Ozone & UV Resistance

The silicon–oxygen backbone is inherently inert to ozone, ultraviolet light and weathering. Silicone seals last decades in outdoor or exposed environments without cracking or degradation.

Electrical Insulation

Outstanding dielectric properties across the full temperature range, making silicone the preferred sealing material for electrical connectors, sensor housings, LED assemblies and high-voltage insulators.

Low Compression Set

Silicone maintains elastic recovery even after long-term compression at elevated temperatures — compression set of 15–30 % at 150 °C ensures reliable static sealing over extended service intervals.

Colour & Translucency Options

Available in virtually any colour including translucent and white, enabling colour-coded identification on production lines and meeting aesthetic requirements in consumer and medical products.

Limitations

Where silicone is not recommended

Low Tear & Abrasion Resistance

Silicone's tensile strength (~7 MPa) and tear resistance are substantially lower than NBR, FKM or HNBR. It is best suited for static seals; dynamic or high-friction applications will cause rapid wear.

Petroleum Fuels & Oils

Standard VMQ swells and degrades in petroleum-based fuels, hydrocarbon oils and many non-polar solvents. Where fuel or oil contact is expected, fluorosilicone (FVMQ) or FKM should be considered.

Concentrated Acids & Alkalis

Strong mineral acids and concentrated caustic solutions attack silicone rubber. Mild acids and dilute alkalis are generally acceptable — consult FITCO's chemical compatibility guide for specific media.

Steam Above 150 °C

While silicone tolerates dry heat to 200 °C+, prolonged exposure to pressurised steam above 150 °C can cause reversion (softening). EPDM or FFKM are better choices for high-pressure steam service.

Applications

Where silicone seals are used

Food & Beverage

Dairy equipment, brewing and bottling lines, beverage dispensers, baking ovens, food-processing machinery — FDA-grade silicone O-rings withstand CIP cleaning cycles and wide temperature swings without imparting taste or odour.

Medical & Pharmaceutical

Surgical instruments, drug-delivery devices, ventilators, blood-handling equipment, sterile packaging. USP Class VI-compliant silicone provides biocompatibility and resistance to autoclave sterilisation.

Automotive & Aerospace

Turbocharger hose connectors, sensor housings, lighting assemblies, EV battery-pack seals. Aerospace uses PVMQ grades for extreme low-temperature flexibility in fuel systems and environmental controls.

Electronics & Lighting

LED lens gaskets, connector seals, display bezels, outdoor enclosure gaskets — silicone's electrical insulation, UV stability and wide operating temperature make it the standard for electronics sealing.

Available as