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Back-Up Ring Kits

Extrusion failure is one of the most common types of O-ring failure. When the pressure becomes too great, the O-ring will actually extrude into the clearance gap. This will quickly nibble the O-ring away causing a loss of material, and once sufficient material is lost, seal failure will quickly follow. 

There are three options to prevent this, the first of which is to reduce the clearances to lower the extrusion gap. This is obviously an expensive option, so a cheaper solution is to raise the durometer of the O-ring. Although, a higher durometer O-ring offers superior extrusion resistance, the fact that harder durometer materials have limited low pressure sealability and is often difficult to source due to material availability. The last and best option is the addition of a backup ring. A backup ring is a ring of hard, extrusion resistant material such as high durometer nitrile, nylon, Hytrel, or PTFE. A back-up ring is designed to fit between the O-ring and the extrusion gap and prevent the extrusion of the O-ring. 





Image Model+ Item Name Stock Price Quantity Discounts
Back-up Rings Nitrile Duro 90 Kit 36-Sizes 293-Pieces K293X36B

Back-up Rings Nitrile Duro 90 Kit 36-Sizes 293-Pieces

Contoured Back-up Ring Kit Contoured back-up rings are anti-extrusion devices, generally recommended when systemic pressure exceeds 1500 psi. The...
0
$39.00

Add:

Quantity Discounts
1$39.00
2-9$35.10
10+$29.25
Back-Up Ring Kit - 510 Piece Kit 25 Sizes - 1/16" C/S MBOX1-K510X25BU90

Back-Up Ring Kit - 510 Piece Kit 25 Sizes - 1/16" C/S

510 Piece Deluxe Contoured Back-up Ring Kit Contoured back-up rings are anti-extrusion devices, generally recommended when systemic pressure exceeds...
0
$69.00

Add:

Quantity Discounts
1$69.00
2-9$62.10
10+$51.75
Back-Up Ring Kit - 440 Piece Kit 24 Sizes - 3/32" C/S MBOX2-K440X24BU90

Back-Up Ring Kit - 440 Piece Kit 24 Sizes - 3/32" C/S

440 Piece Deluxe Contoured Back-up Ring Kit Contoured back-up rings are anti-extrusion devices, generally recommended when systemic pressure exceeds...
1
$83.50

Add:

Quantity Discounts
1$83.50
2-9$75.15
10+$62.63
Back-Up Ring Kit - 280 Piece Kit 19 Sizes - 1/8" C/S MBOX3-K280X19BU90

Back-Up Ring Kit - 280 Piece Kit 19 Sizes - 1/8" C/S

280 Piece Deluxe Contoured Back-up Ring Kit Contoured back-up rings are anti-extrusion devices, generally recommended when systemic pressure exceeds...
1
$84.00

Add:

Quantity Discounts
1$84.00
2-9$75.60
10+$63.00


What are the most common O-ring compounds?

We stock O-Rings in over 20 different compounds and durometers the following six are the standard rubber materials in a range of durometers (Shore A) hardness to satisfy practically any service condition:

Buna-N O-Rings / Nitrile O-Rings / NBR: Nitrile (Buna-N) is the most widely used elastomer due to its excellent resistance to petroleum products, operating temperature range (-40°F to +257°F) and one of the best performance-to-cost values. It's an ideal material for aerospace, automotive, propane and natural gas applications. Special Hydrogenated Nitrile (HNBR) compounds can improve resistance to direct ozone, sunlight, and weather exposure while increasing temperature range to +300°F.
AS-568 Buna-N O-Rings | Metric Buna-N O-Rings

Viton® O-Rings / FKM: Fluorocarbon (Viton®) exhibits exceptional resistance to chemicals, oils, temperature extremes (-13°F to +446°F), low compression set, low gas permeability and excellent aging characteristics. Applications include: aircraft engines, automotive fuel handling systems, and chemical processing industries. FKM is also suitable for high vacuum applications. It is not recommended for exposure to ketones, alkalis, and Skydrol® fluids. Custom compounds are available with improved chemical and low temperature resistance.
AS-568 Viton® O-Rings | Metric Viton® O-Rings

Ethylene-Propylene / EPDM O-Rings: EPDM has outstanding resistance to heat, water and steam, alkali, mild acidic and oxygenated solvents, ozone, and sunlight (-40ºF to +275ºF); but it is not recommended for gasoline, petroleum oil and grease, and hydrocarbon environments. This popular rubber compound is usually the first choice for low torque drive belt applications.
AS-568 EPDM O-Rings | Metric EPDM O-Rings

Silicone O-Rings / VMQ: In the Silicone family, you will find compounds which are superior as static seals in extreme temperature conditions. Standard compounds handle operating temperatures -85º to +400ºF. Silicone compounds are popular in food and medical applications because they are very clean and do not impart odor or taste. Special Phenyl silicones can be used down to -148°F.
AS-568 Silicone O-Rings | Metric Silicone O-Rings

Neoprene® O-Rings / CR: Neoprene (-40º to +250ºF) is reasonably priced and features good resistance to petroleum oils, ozone, sunlight and oxygen aging, relatively low compression set, good resilience and outstanding physical toughness. It is the preferred sealing material for the refrigeration industry because of its resistance to ammonia and Freon®.
AS-568 Neoprene® O-Rings