November 2019

Gasket Materials for Washdown Environment

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.

SBR Sheet – 7 Uses

Natural rubber is an imperfect material for gaskets. While soft and compressible at room temperature it hardens in the cold and has poor weather resistance. Styrene Butadiene Rubber (SBR) is a manmade alternative that comes in mainly in extruded and sheet form. For gaskets, SBR sheet is inexpensive and performs well in a range of applications. Here’s a closer look.

Properties of SBR Sheet

SBR is an abrasion-resistant elastomer manufactured in hardnesses ranging from 50 to 80 Shore A. (50 is firmer than a pencil eraser while 80 feels like a leather belt.) It’s also less variable than natural rubber.

SBR has good impact strength and tensile strength from 400 to 1,000 psi. Consider fabric-reinforced grades for applications needing higher strength.

For gasket applications, SBR sheet has high resilience and low compression set. It resists acids, brake fluid, and moisture but is attacked by oils and hydrocarbons. Useful temperature range is -40°F to 180°F (-40°C to 82°C) though limits vary by grade.

SBR Sheet Availability

SBR is available in sheet and roll form up to 36” wide. Thicknesses are from 1/64” to 1/4” with wider and thicker sheet available for special order. SBR sheet comes mainly in black, red and gray. For other colors please ask.

Applications for SBR Sheet

SBR is a good choice for applications needing flexibility and abrasion resistance. Examples include:

  1. Flaps (access doors and panels, seals around doors.)
  2. Scrapers and wipers (especially those used in low-temperature environments.)
  3. Lining rubber (Placed over workbenches and in drawers, SBR sheet absorbs impacts and prevents damage to tools and workpieces.)
  4. Conveyor Belting
  5. Skirtboards (Rubber strips at the base of walls in high-traffic and washdown environments.)

High resilience and low compression set make it a good two choice for two other types of application:

  1. Brake system seals
  2. Gaskets

The Manmade Alternative

Natural rubber would make an excellent gasket material if it didn’t stiffen in low temperatures and had better weather resistance. SBR sheet has similar useful properties – abrasion resistance, resilience, and strength – without the weaknesses. If you’d like to learn more, specialists at Hennig Gasket can help.