Cleaning is important in many industries, but pharma and food and beverage have it down to a fine art. For those sectors frequent intensive washdowns are a way of life and equipment gaskets must be up to the task. Silicone gasket material and neoprene gasket material are, open-cell foams are not. Here’s some detail.
The Washdown Process
Water heated to 170°F is blasted at 1,500psi of pressure to remove every trace of dirt and contamination. For extra-thorough cleaning caustic chemicals might also be added, creating an even more challenging sealing environment.
NEMA and IP Ratings
Enclosures are rated for the “ingress protection” they provide. NEMA is the US system while elsewhere they like the “IP” categories. A NEMA 4 rating, broadly equivalent to IP66, means an enclosure is designed to resist jets of high-pressure water from a hose. In other words, washdown. A step up in protection is NEMA 4x or IP69k. NEMA 4x protects against aggressive chemicals while IP69k is a rating for steam jet cleaning.
Gasket Materials for Washdown Environments : EPDM, Silicone, Neoprene
First, note that equipment and enclosures should be designed in a way that prevents water jets from directly impinging on the gasket material. Even with that though, the gasket outer surface is still going to get soaked.
This is why open-cell foam is not appropriate. It’s going to let water soak through to the interior. Closed-cell foam is better and solid better still, (though not as soft or compressible.)
Second, the gasket material must resist attack by hot water, possibly incorporating caustic chemicals. Good candidates are EPDM, silicone, and neoprene. Some points to note about each of these are:
- EPDM gasket material is also UV-resistant. That makes it a good choice outdoors and wherever UV light is used.
- Silicone gasket material is flexible from –100 to 500°F.
- Neoprene gasket material works over a range from -40 to 250°F. It also has good oil resistance but is attacked by ozone.
Ask the Experts
You should know the strengths and limitations of the gasket materials you’re considering. The specialists at Hennig Gasket have a lot of knowledge and experience. Call them or reach out by email.