Low Temperature FKM vs. Low Temperature Silicone: Choosing the Right Elastomer for Extreme Cold
Updated: Sep 29, 2025
Introduction
Sealing systems often operate in environments where temperatures plunge far below freezing. From aerospace hydraulics at altitude, to cryogenic pumps in industrial facilities, to medical equipment undergoing sterilization cycles, elastomers must remain flexible and reliable at temperatures where most materials become brittle. Choosing the wrong material leads to leakage, premature failure, and costly downtime. Get in touch with the Canyon Components engineering team now!
Two of the most common elastomer families used for cold service are low temperature FKM and low temperature silicone (VMQ, PVMQ, FVMQ). Both materials are widely available, customizable, and versatile, but they serve different niches.
This blog provides a technical comparison of low temperature FKM and silicone, analyzing performance characteristics, limitations, and applications. The goal is to help engineers and procurement teams make informed material selections for demanding cold environments.
Understanding Low Temperature FKM
What Is FKM?
FKM, often recognized under trade names like Viton®, is a family of fluorocarbon elastomers. Standard grades of FKM typically perform down to around –26 °C to –30 °C before stiffening significantly. To address this, manufacturers developed low temperature FKMs, including GLT, GFLT, and specialty copolymers that remain flexible to –40 °C or even lower. Get in touch with the Canyon Components engineering team now!
Properties of Low Temperature FKM
- Cold Flexibility: Modified polymer backbones reduce glass transition temperature (Tg), allowing operation down to approximately –40 °C, with some blends approaching –50 °C.
- Chemical Resistance: Excellent resistance to fuels, oils, and aggressive chemicals, a hallmark of all fluorocarbon materials.
- Compression Set: Superior to many other elastomers, enabling long service life in static and dynamic sealing.
- Durability: Resistant to weathering, ozone, and many aggressive industrial fluids.
Limitations
- Not as flexible as silicone at extreme lows: Once past –40 °C, stiffness increases quickly.
- Cost: Generally more expensive than silicone.
- Permeation: While low, not as negligible as PTFE or perfluoroelastomer options.
Understanding Low Temperature Silicone
What Is Silicone?
Silicone elastomers (VMQ, PVMQ, FVMQ) are known for their broad service range and biocompatibility. Standard silicone remains flexible down to –60 °C to -70 °C, while specialized formulations can function at temperatures lower than –110 °C, making it one of the most cold-flexible sealing materials available. Get in touch with the Canyon Components engineering team now!
Properties of Low Temperature Silicone
- Cold Flexibility: Exceptional performance in cryogenic and ultra-low temperature environments.
- Purity and Biocompatibility: Silicone is physiologically inert, making it common in medical devices, food processing, and pharmaceutical applications.
- Thermal Range: Broadest of any elastomer family, typically –60 °C to +200 °C, with some grades pushing all the way up to 315°C.
- Color and Identification: Available in translucent and pigmented grades for easy identification in regulated industries.
Limitations
- Chemical Resistance: Poor resistance to fuels, oils, and many solvents compared to FKM.
- Tear and Wear Resistance: Lower mechanical strength, not ideal for dynamic sealing under high stress.
- Compression Set: Higher than FKM, which can shorten service life under long-term compression.
Head-to-Head Comparison
| Property | Low Temperature FKM | Low Temperature Silicone |
|---|---|---|
| Low Temp Flexibility | GLT: –40 °C XLT: -50C | PVMQ –110 °C depending on blend |
| High Temp Resistance | Up to 225 °C | Up to 200 to 315 °C depending on blend |
| Chemical Resistance | Excellent with fuels, oils, solvents | Poor in fuels and oils; excellent in water and many inert environments |
| Compression Set | Low, excellent for sealing longevity | Higher, shorter life in static compression |
| Tear/Tensile Strength | Higher mechanical strength | Lower tear and abrasion resistance |
| Biocompatibility | Limited to specialty grades | Excellent biocompatibility |
| Cost | Higher material cost | Generally lower |
| Industries | Aerospace, automotive, oil & gas, chemical processing | Medical, pharmaceutical, cryogenic, food & beverage |
Industry Applications
Aerospace and Defense
- Low Temperature FKM: Used in aerospace fuel systems, where resistance to jet fuel, hydraulic fluids, and lubricants is critical. Its ability to withstand both cold temperatures at altitude and aggressive chemicals makes it a go-to solution.
- Silicone: Chosen where extreme flexibility is needed in cold air environments, such as sealing pressurized cabins or electronic housings. However, it is not preferred for direct fuel contact. Get in touch with the Canyon Components engineering team now!
Chemical Processing and Oil & Gas
- Low Temperature FKM: The better option, thanks to its resistance to hydrocarbons, acids, and aggressive solvents. Its cold flexibility allows outdoor equipment and pumps to continue operating in winter conditions.
- Silicone: Rarely used here due to chemical incompatibility, unless in non-contact gasketing or insulating roles.
Medical and Pharmaceutical
- Silicone: Dominates due to biocompatibility, USP Class VI and ISO 10993 certifications, and sterilization resistance. Cryogenic medical storage systems rely on silicone’s flexibility.
- Low Temperature FKM: Sometimes chosen for equipment where exposure to solvents or aggressive cleaning agents is unavoidable.
Cryogenic and Vacuum Applications
- Silicone: Excellent down to –100 °C, making it suitable for laboratory and vacuum environments where purity and flexibility matter.
- Low Temperature FKM: Used where chemical resistance must be balanced with vacuum performance, though FFKM or PTFE often provide superior solutions for extreme cases.
Automotive and Industrial
- Low Temperature FKM: Seals in fuel injection systems and transmission components exposed to low temperatures.
- Silicone: Used in applications requiring flexibility, such as gaskets, hoses, and sealing of electronics in cold climates.
Case Study: Aerospace Hydraulic System
An aerospace OEM required seals that could handle both cold soak at altitude (–40 °C) and long exposure to phosphate ester hydraulic fluids. Silicone was initially considered for cold flexibility but failed chemical resistance tests. A low temperature FKM was chosen, which balanced cold flexibility with fluid compatibility, extending service life and preventing costly in-flight leakage.
Case Study: Cryogenic Medical Storage
A pharmaceutical company needed seals for cryogenic vials stored in liquid nitrogen. Silicone O-rings provided reliable sealing performance down to –80 °C and maintained biocompatibility for sensitive medical applications. Low temperature FKM was not considered, as chemical compatibility with fuels and oils was irrelevant in this scenario.
Design Considerations
Choosing the Right Material
When deciding between low temperature FKM and silicone, engineers should weigh:
- Temperature extremes: If operation falls below –50 °C, silicone is generally necessary.
- Media compatibility: If exposure to fuels, oils, or aggressive chemicals is expected, FKM is the superior option.
- Application type: For static seals in clean environments, silicone works well. For dynamic or chemically harsh environments, FKM is preferred.
Multi-Material Strategies
Some designs incorporate both materials: silicone seals for cryogenic containment, FKM seals for chemical exposure. Canyon Components frequently advises customers on hybrid solutions to balance competing requirements. Get in touch with the Canyon Components engineering team now!
Future Developments
Advances in elastomer chemistry continue to blur the line between FKM and silicone capabilities.
- Ultra-low temperature FKMs are being developed with Tg values approaching –50 °C.
- High-strength silicones with improved tear resistance are entering aerospace and industrial markets.
- Composite seals combining PTFE jackets with elastomer cores provide hybrid performance for the most demanding systems. Get in touch with the Canyon Components engineering team now!
Conclusion
Both low temperature FKM and silicone play critical roles in sealing technology, but they serve distinct needs:
- Choose low temperature FKM when chemical resistance to fuels, oils, or solvents is paramount, and temperatures remain above –40 °C.
- Choose low temperature silicone when extreme cold flexibility, biocompatibility, or cleanroom compatibility are more important than chemical resistance.
At Canyon Components, we provide both low temperature FKM and silicone in O-rings, gaskets, tubing, and custom molded parts. By understanding the trade-offs, engineers can select the right elastomer for their environment, ensuring long-term performance, safety, and reliability. Get in touch with the Canyon Components engineering team now!
