EPDM Gaskets

UV Resistant Rubber Sheet

You’ve probably seen dried up and cracked nitrile and neoprene gaskets. Chances are, you’ve replaced a few too! In many cases the culprit is ozone. Here we’ll explain what ozone is, how it forms and what processes/activities expose gasket materials to ozone. Then we’ll suggest materials to use if you have an ozone problem which includes UV resistant rubber sheet.

An oxygen compound

Ozone is just oxygen atoms bound together in groups of three. Its chemical symbol is O3. In nature, ozone exists only in the stratosphere, a layer of the atmosphere five to thirty miles up. However, it can be produced artificially at ground level, and those are the processes that break down nitrile and neoprene gasket materials.

Oxygen atoms react readily with other elements. That’s why iron rusts and aluminum oxidizes. O3 is even more reactive than regular O2, so oxidizes materials even faster. When it contacts gasket materials like nitrile rubber (Buna-N,) natural rubber and neoprene it changes how their polymers are crosslinked. This hardens the material, which then cracks under load.

Ozone-producing processes

Ozone forms in the presence of ultraviolet (UV) light and electrical sparks. Both can break the bonds between oxygen and itself and other elements to free up individual atoms. These quickly recombine as O3.

UV light is widely used for purification and disinfection. Many city water systems use UV purification and UV disinfection is widespread in the medical sector. Ozone is a natural byproduct and itself is used for purification.

Electrical sparks are common around brushed electric motors, especially those using high voltages. High voltage switchgear is another source of ozone.

UV Resistant Rubber Sheet

When choosing a gasket material for an ozone-producing environment stay away from nitrile rubber and neoprene. Instead, consider silicone and EPDM materials. These are available with similar properties to nitrile and neoprene but are less susceptible to oxidation. Other good choices are PTFE and Viton/FKM.

Talk to the UV resistant rubber sheet materials specialists

If you think ozone could be an issue in a gasket application, talk to our specialists. They’ll help you select an EDPM, silicone or other ozone-resistant material suitable for your application.

Low Temperature Gasket Material

Many elastomeric gasket materials have a problem with low temperatures. Here we’ll look at some applications that pose challenges and suggest low-temperature gasket materials worth considering.

Low-Temperature Gasket Material Applications

Seals and gaskets are used in many low-temperature environments. One of the most common is food storage. Freezers and cold rooms are typically kept between -80 and 20°F, depending on the application. Pharmaceuticals and medical products are other industries with low-temperature storage requirements.

Industries that do product testing often employ climatic chambers. These need effective seals to minimize the expense of maintaining low temperatures, and it’s also important to consider the equipment inside. And as Chicagoland residents understand, midwest winters can challenge sealing materials used outdoors, especially if exposed to wind.

Glass transition and TR10

Polymers get their flexibility from chains of molecules moving against one another. As temperatures fall the chains are less able to move and eventually become fixed. Materials scientists call this point the glass transition temperature.

For people who need to choose and use gasket material a more useful indicator of low-temperature flexibility is the TR10 value. This was explained in, “What is TR-10 (temperature of retraction) for Gasket Material?

Good Low-Temperature Gasket Material Choices

Oil-resistant FKM only goes down to around 5°F. NBR is useable as low as -20°F and some specialized grades will go lower. However, these aren’t low enough for many freezer-type applications. Silicon is good for temperatures as low as -65°F and fluorosilicon will go to -80°F but both are expensive. That leaves cost-effective EPDM as an excellent low-temperature gasket material.

The TR10 value for EPDM is between -49 and 9°F, depending on grade. That makes EPDM seals a good choice for many commercial and industrial low-temperature storage facilities. Furthermore, EPDM is available in FDA-approved grades for food industry use.

The chief limitation of EPDM seals is poor resistance to mineral oils and hydrocarbon products. They are good with steam and hot water though, as well as caustic cleaners.

Consider price as well as performance

In low temperatures, many gasket materials become too stiff to seal effectively. Silicon offers good performance but less expensive EPDM comes close for many applications.

Best Gasket Material for Nitrogen

Many industries use nitrogen. Some users even generate their gas on-site. If your company is among them you ought to be familiar with the best gasket materials to use.

Industrial Uses of Nitrogen

Liquid nitrogen is used when very low temperatures are needed. This is often for preserving biological samples or other organic material although other uses include cooling for superconductors and to aid in machining.

Applications for gaseous nitrogen include fertilizer production, food preservation, and annealing stainless steel. It’s also used in the production of electronic components like transistors and diodes.

Nitrogen Production and Storage

Nitrogen is produced by separation from air. (The air around us is approximately 78% nitrogen.) There are two methods:

  • fractional distillation
  • pressure swing adsorption (PSA).

Distillation entails chilling air until it becomes liquid, then raising the temperature slowly to let the individual components boil. In contrast, PSA is done at ambient temperature and in simple terms consists of pushing air through a membrane that separates the various constituents.

Distillation produces higher purity gas but is energy-intensive. PSA scales more easily for local or on-site gas generation, and this is the process most often adopted by manufacturers who don’t want to depend on deliveries and storage.

Suitable Materials for Gaskets in Nitrogen Systems

Nitrile and natural rubber gasket materials are good choices for gaseous nitrogen, although EPDM is generally considered best. EPDM gasket material has good heat resistance and a working temperature range of around -60 to 320°F (-50 to 160C). Resistance to oxidation, UV, ozone, and abrasion are all good and it also withstands water, acids, and alkalies along with ketones and alcohols.

Handling liquid nitrogen demands a gasket material with excellent low-temperature performance. If an elastomer is needed Santoprene® may be a good choice. A trade name for a class of thermoplastic vulcanizate (TPV) materials, this behaves much like EDPM but some grades remain flexible at even lower temperatures.

Consult a Materials Expert

Every gasket application is different so it’s always prudent to learn more about the material before purchasing. Specialists at Hennig Gasket are ready to help.

Understanding EPDM Gasket Material

When buying elastomeric material to seal a joint many people go straight for neoprene gaskets. Neoprene works well in many applications, but there are cases where other materials will perform better. One such material that should be considered for outdoor use, or situations where abrasive wear is possible, is EPDM.

EPDM is rubber-like in appearance and properties, so good compressibility and recovery is a hallmark of EPDM gasket material. Like all gasket materials though, it has strengths and weaknesses. This overview should help prospective buyers decide whether to consider EPDM gaskets.

Chemistry and properties

EPDM is an acronym for ethylene-propylene diene monomer. Ethylene and propylene are hydrocarbons and gases at room temperature, yet combine to make solid polymers like polyethylene and polypropylene. By adjusting the proportions and controlling the polymerization process it’s possible to create long molecular chains with more rubbery properties. That’s EPDM.

Sometimes referred to just as EPM, EPDM is a very stable material that resists heat, oxidation, and the aging effects of ultraviolet light. Unlike many other elastomers it’s flexible at low temperatures, and depending on how it’s formulated, works over a range of -60°F to 300°F.

EPDM has good mechanical properties too. Tensile strength is in the range of 7 to 21 Mpa, which is higher than other elastomers like silicone (5 – 10 MPa), nitrile (12 – 15 MPa) and neoprene (5 – 8 MPa). It’s also resistant to abrasive wear, which can’t be said for silicone.

In terms of chemical resistance, EPDM holds up well to acids and alkalies and is a good choice when dealing with both brake fluids and ketones. It also has good resistance to steam. Where it fares less well is against hydrocarbon oils and petroleum products as these produce swelling.

EPDM gasket applications

Relatively immune to sunlight, water and low temperatures, EPDM is often a smart choice for gaskets that will be outside. Good compression set resistance means it recovers well in applications where a joint may open up from time to time, and high electrical resistance means EPDM gaskets may be appropriate for some electrical installations.

A silicone competitor

In the gasket world silicone is known as a high performance material with a wide temperature range and good flexibility. In many applications though, an EPDM gasket could be a more cost-effective choice. Its temperature range is almost as wide and it’s a stronger, more durable material.

Consult the materials specialists

EPDM is available in a wide range of formulations with properties that vary considerably. To get a better understanding of EPDM gasket material options for your application a discussion with the specialists at Hennig Gasket & Seals Inc. is recommended.  Contact us today.

How Hot is too Hot? Choosing the Right Gasket Material for a Non-Metallic Gasket

For non-metallic gasket applications, the operating temperature of the finished product is a major consideration. You need to know the temperature range (and other strengths and weaknesses) of potential materials so you can get the most durable custom gaskets and seals. Otherwise, they could prematurely harden, crack, deform and lose strength, elasticity and resilience, etc.

The following is a list of common non-metallic gasket materials, their properties and their most stable operating temperature ranges (in Fahrenheit). Understand that while there may be wiggle room on either end, it’s best to aim for somewhere in the middle of each particular material’s temperature range so that the gasket or seal performs optimally for the longest period of time before replacement is needed.

Nitrile: -30 to 250F (very resistant to oils, aromatic hydrocarbons, fuels and solvents).

Neoprene: -35 to 225F (resistant to weather, water, combustion and a long list of chemicals).

Polyurethane: -35 to 225F (resistant to oxygen, ozone, cracking, abrasion, cuts, grease and heavy loads; frequently used in machine mounts, electrical equipment wear pads and applications needing shock absorption).

Ethylene Propylene: -70 to 250F (resists severe weather conditions, acids, oxygen, alkalis, hot and cold water and ketones; not suitable for use with oils or fuels).

Fluorocarbon: -15 to 400F (its low friction and resistance to wear and tear make this a good material for gaskets that endure movement, a wide temperature variation and frequent reassembly).

Silicone: -65 to 450F (very resistant to hot, cold and oxygen, but poor resistance to oils and fuels; frequently used in food processing and medical applications).

Polytetrafluoroethylene: -238 to 574F (extremely wide temperature range, also stands up to harsh conditions of all sorts; frequently used in food processing, pharmaceutical, laboratory, semi-conductor, petrochemical and chemical and electrical applications).

Temperature range is, of course, just one aspect of a non-metallic gasket material that you will need to consider before project implementation; nevertheless, temperature tolerance is crucial. If you need custom gaskets and seals for your project, please call us at 1-800-747-7661 to discuss your needs with us.

Properties of Neoprene Gasket Material

Neoprene, which is also known as “polychloroprene,” is a type of synthetic rubber produced by the polymerization of chloroprene. Neoprene gasket material has become very common due to the fact that it resists the likes of ozone, sunlight, oxidation and many petroleum derivatives. Additionally, neoprene is characterized as being weather-, combustion-, water- and chemical-resistant. As you can see, it’s popular because it is resistant to many types of damages. What’s more, it’s also resistant to damage from twisting and flexing.

Here’s a closer look at the properties of neoprene so you can judge whether or not it’s a good material for your application:

  • Stretch and cushioning properties: Neoprene is elastic and form-fitting, able to conform to various sizes and shapes. It’s also cushioning, able to absorb shock.
  • Various grades available: From cloth inserted neoprene, which is reinforced with nylon for additional stability, to flame retardant neoprene, which passes a variety of flammability specifications, there are several grades available to suit any application. Other popular grades include commercial, FDA approved, diaphragm and high tensile strength.
  • General gauge thicknesses vary in size from 3/32-inch up to 2 inches.
  • Hardness ratings vary from 40 to 80.
  • Plate finish.
  • Neoprene can withstand temperatures ranging from -20 degrees F to 180 degrees F.
  • Tensile strength ranges from 900 to 1,000 PSI.
  • Elongation ranges from 350% to 400%.
  • Finally, widths are 36 inches, 48 inches or 72 inches.
  • Pressure sensitive adhesive, or PSA, are available upon request.
  • We fabricate neoprene gaskets through proven manufacturing processes that include waterjet cutting, flash cutting and die cutting.

One other neat feature about neoprene is that it’s impermeable, meaning that it can work as a tight barrier to prevent the escaping of gases or liquids.

For more information on the neoprene material and neoprene gaskets, and to speak with someone about placing an order, contact us today.