Low temperatures play havoc with elastomeric gasket materials, as NASA will testify. (Details of how seal failure caused the Challenger disaster are available on the NASA website.) The issue is that at low temperatures gasket materials like nitrile rubber and neoprene become stiffer and less able to fill gaps. The TR10 number, derived from ASTM D1392, shows the temperature at which this stiffening affects sealing performance. The problem for problem for people buying gasket material is knowing how low temperatures can go.
Global lows
Military Standard MIL_HDBK_310_1851 “Global Climatic Data For Developing Military Products”, tells equipment developers what conditions to design for. This notes that the lowest temperature ever recorded is -68°C (-90°F), in the USSR. Statistically, the lowest temperature to be expected in the coldest regions of the world is -69°C (-92°F).
Low temperatures in the USA
Weather.com tells us the lowest temperature experienced in the U.S. is -62°C (-80°F), in Prospect Creek Alaska. Closer to home, the lowest in the contiguous 48 is -57°C (-70°F), measured at Rogers Pass, Montana. For those in the Midwest, record lows in Illinois, Indiana and Ohio are in the -34°C (-30°F) range, while Michigan, Wisconsin and Iowa have records ranging from -43°C to -48°C (-45°F to -55°F).
Of course, this is without the effects of wind chill. Air flowing over surfaces takes heat away, making the temperature appear lower than it actually is. And the harder the wind blows, the greater the cooling effect.
Implications for gasket material selection
When selecting gasket material for outdoor applications it’s essential to determine the lowest possible temperature. Not doing so risks leaks during periods of extreme cold, which is never a good time to be replacing a failed gasket!
Most nitrile rubber, EPDM and neoprene gasket materials work down to around -46°C (-50°F). HNBR is limited to around -40°C (-40°F) while silicone will endure temperatures down to around -59°C (-75°F). (values vary for individual material grades.)
If a gasket might be exposed to low temperatures material should be selected to suit. Specialists at Hennig Gasket will be happy to advise.
