Environmental Gaskets and Seals

Environmental gaskets or environmental seals are terms used to refer to gasketing for outdoor weather conditions. These are also referred to as rain gaskets, UV resistant gaskets, heat resistant gaskets and freeze resistant gaskets. “Environmental” usually incorporates all of these properties. The function is to seal out rain, not degrade under UV and high temperatures and not crack in freezing temperatures. Preventing leaking in wind driven rain, melting snow and ice (that may pool on an enclosure) are also points to consider.

Environmental sealing applications may require NEMA, UL 50 or IP testing. Common standards are NEMA Type 3 thru Type 6, UL 50 follows a similar format. IP63, IP64, and IP65 are often referenced for outdoor gasketing applications such as lighting and portable electronics. Even if NEMA, UL or IP are not required, they are good references to help describe the type of sealing needed for a particular application.

Washdown Gaskets

Washdown gaskets are a type of environmental gaskets. While they could be used outside, they could also be used indoors in a manufacturing environment that has routine pressure washing. Protecting digital displays and controls such as touch screens is another critical application. Wash down enclosures usually require the next level up; NEMA 4, NEMA 5, NEMA 6, IP65 and IP66. These specifications are more aggressive – water sealing against pressurized jets. Due to the high pressures and water volumes, successful sealing is shared between a good enclosure design and the proper gasket material.

Material Candidates for Washdown Gaskets

• Closed cell silicone foam (requires good protection from direct blast)
• Closed cell silicone sponge (meets many Mil-STD 810 requirements)
• Solid silicone (excellent sealing, requires higher clamp loads)
• Closed cell EPDM, neoprene, and urethane sponge (lower cost, moderate longevity)