Electrical and electronic equipment should always go in an enclosure designed to protect it from water and dust. However, the enclosure is only as good as the gasket that seals it.
An electrical enclosure gasket needs to accommodate irregularities in the surfaces of both door and enclosure, and continue to seal after repeated opening and closing. It should also resist varying degrees of external pressure, depending the standard applicable.
Outdoors, the threat usually comes from rain, which may be wind-blown but seldom impacts the enclosure with significant force. In industrial situations, especially in the food, medical and pharma sectors, enclosures are often expected to resist high pressure washdowns.
Standards for ‘ingress protection’ are promulgated by several organizations, notably the International Electrotechnical Commission (IEC,) NEMA and UL. The IEC 60529 standard defines the IP levels that many engineers know. (IP65, 66 and so on.) NEMA standards are seen as more demanding in terms of not allowing water penetration but only address design intent. Only UL insists on third party testing to verify compliance.
Three types of gasket are used in enclosures:
- strip
- ‘foam-in-place’ (FIP)
- die-cut
As the name suggests, a strip gasket is cut from sealing material and applied in lengths to the enclosure door. Inevitably that leaves gaps. Dust may be excluded but water can almost certainly penetrate.
For an FIP gasket liquid polyurethane is applied to one of the mating surfaces. As it cures a reaction makes it foam, producing a joint-free gasket. It’s a popular approach but tends to be messy and can be slow.
Die-cut gaskets are stamped from roll or sheet material and are the shape of the enclosure sealing face. The absence of joints means no leak paths. Material selection depends on applications requirements although neoprene or silicone are often good choices. Installation is just a matter of fitting them in place, usually with an adhesive.
Hennig Gasket & Seals can die-cut gaskets as large as 36″ x 62″. For larger gaskets flash (an oscillating knife,) or waterjet cutting are available. Contact us Today.
