Filter Sealants Considerations

Filtration Table of Contents

Filter sealants used to provide a leak-free bond between the filter pack and case installation must be resistant to heat and moisture, noncombustible, fire-resistant, or self-extinguishing, as well as capable of maintaining a reliable seal under continuous exposure to design operating conditions.

 Rubber-based adhesives compounded with chlorine or bromine to ensure self-extinguishing when exposed to ignition are acceptable, but catalytically cured solid and foamed polyurethanes containing additives for combustion suppression are the sealants of choice for most filter manufacturers.

 Sealants may be required to maintain their integrity over a wide temperature range. Filters designed to operate at temperatures above 392 degrees Fahrenheit (200 degrees Celsius) have been sealed with compression-packed glass fibers and with ceramic cements reinforced with glass fibers, and have been hardened thermally. Compression-packed glass fiber seals are sometimes found to be damaged after shipment. The ceramic seal is often too brittle to withstand commercial shipment. Room temperature vulcanizing silicone rubber sealants have been used successfully at operating temperatures only slightly lower than 392 degrees Fahrenheit (200 degrees Celsius).