High Temperature Air Filter Design Considerations

Filtration Filter Table of Contents

Although some air filter system components are pre-qualified to operate in a given temperature range, the air filter system designer must verify all components of the system will function at the maximum and minimum temperature conditions for the specified application. If the temperature range of the specific application exceeds the filters design qualification temperature, pre-qualification is necessary to meet the operational and design life requirements of the system.

In general, continuous operation at high temperature (greater than 250 degrees Fahrenheit) is detrimental to both HEPA filters and activated carbon-filled absorbers. At high temperatures, the shear strength of adhesives and binders used in the manufacture of HEPA filters and filter media may diminish, thereby limiting the safe pressure drop to which they can be subjected. The limiting temperature varies with the specific adhesive and binders used. High temperature filter manufacturers have designed HEPA filters for temperatures above 250 degrees Fahrenheit (a 500-degree Fahrenheit filter is also available). The filter manufacturer should provide objective evidence that the filters are qualified for the higher-temperature environments of the specific application.

For high-temperature applications, particulate filtration can be accomplished with the use of metal filters constructed of sintered metal or metal mesh. Metal filters are manufactured for medium efficiency and HEPA efficiency ranges. Due to their relatively high cost, metal filters should be considered only for those applications where standard glass fiber filters would not meet the environmental or design conditions.

When temperatures higher than the operating limits of air filter system components must be accommodated, chilled water coils, heat sinks, dilution with cooler air, or some other means of cooling must be provided to reduce temperatures to levels that the components can tolerate.