Many elastomeric gasket materials have a problem with low temperatures. Here we’ll look at some applications that pose challenges and suggest low-temperature gasket materials worth considering.
Low-Temperature Gasket Material Applications
Seals and gaskets are used in many low-temperature environments. One of the most common is food storage. Freezers and cold rooms are typically kept between -80 and 20°F, depending on the application. Pharmaceuticals and medical products are other industries with low-temperature storage requirements.
Industries that do product testing often employ climatic chambers. These need effective seals to minimize the expense of maintaining low temperatures, and it’s also important to consider the equipment inside. And as Chicagoland residents understand, midwest winters can challenge sealing materials used outdoors, especially if exposed to wind.
Glass transition and TR10
Polymers get their flexibility from chains of molecules moving against one another. As temperatures fall the chains are less able to move and eventually become fixed. Materials scientists call this point the glass transition temperature.
For people who need to choose and use gasket material a more useful indicator of low-temperature flexibility is the TR10 value. This was explained in, “What is TR-10 (temperature of retraction) for Gasket Material?”
Good Low-Temperature Gasket Material Choices
Oil-resistant FKM only goes down to around 5°F. NBR is useable as low as -20°F and some specialized grades will go lower. However, these aren’t low enough for many freezer-type applications. Silicon is good for temperatures as low as -65°F and fluorosilicon will go to -80°F but both are expensive. That leaves cost-effective EPDM as an excellent low-temperature gasket material.
The TR10 value for EPDM is between -49 and 9°F, depending on grade. That makes EPDM seals a good choice for many commercial and industrial low-temperature storage facilities. Furthermore, EPDM is available in FDA-approved grades for food industry use.
The chief limitation of EPDM seals is poor resistance to mineral oils and hydrocarbon products. They are good with steam and hot water though, as well as caustic cleaners.
Consider price as well as performance
In low temperatures, many gasket materials become too stiff to seal effectively. Silicon offers good performance but less expensive EPDM comes close for many applications.