Low temperature sealing capability

February 25, 2016 – by Eastern Seals

There are many applications requiring O-rings that operate at low temperatures. Despite this, low temperature performance is often overlooked when considering seal performance.

O-rings subjected to low temperatures can typically fail for the following reasons:

– The seal material hardens when the low temperature limit is reached, and resists deformation to pressure, causing leak paths.
– The O-ring will take a higher than normal compression set – this allows for leakage.

It is vital that the correct material is selected to achieve the required performance from the seal at low temperatures.

Standard low temperature tests are performed to measure material performance. These tests include:

• Brittleness (ASTM D2137) – measures the ability of a material to withstand breaking when bent at a given temperature for a period of time.
• Temperature Retraction (ASTM D1329) – measures the temperature at which a material returns from an elongated state.
• Another good indicator for seal performance is Compression Set. This test gives a clear indication of what will happen to a material when exposed to low temperature and allowed to return to higher temperatures.

Eastern Seals UK Ltd. can offer Low Temperature O-rings that meet the demands required for a wide range of applications. The company supplies a variety of low temperature materials to suit each unique application. These include: FKM LT, Viton GLT, Nitrile LT, HNBR LT and Silicone LT.

Eastern Seals also offers specialist low temperature O-rings. From Anti-Explosive Decompression compounds, Norsok M-710 approved compounds to specialist seals for Cryogenic applications.

Encapsulated O-Rings (FEPs and PFAs) are recommended when a standard O-Ring has inadequate chemical resistance for an application, and a solid PTFE O-Ring does not have the elasticity for reliable, long term fluid sealing. FEP with a Silicone Core will seal down to -60°C, however, a spring version is also available for Cryogenic applications to -250°C. [Read more on Encapsulated O-Rings…]

Industries including pharmaceutical, medical and chemical processing all encounter low temperature cryogenic conditions. They experience situations where it is very difficult to achieve effective liquid or gas sealing. Spring O-rings are ideal for sealing at extremely low temperatures where traditional elastomers suffer from brittleness. Low compression sets allow effective sealing as low as -250°C. Prices are very reasonable considering the technical merits of this product. Lead times for Spring O-rings are approximately 14 to 21 days for the standard range.

Because of the diverse range of markets, a number of high performance materials are required to satisfy the demand for superior chemical sealing, reliability and long service life. Contact Eastern Seals’ Technical team to discuss the best sealing solution for your process.