Seals survive ozone attacks in storage

Harder NBR material is designed for seals with optimised ozone resistance.

Busak + Shamban has developed a new harder NBR material designed for optimised ozone resistance.

Engineered to prevent cracking when O-rings are stored in an elongated state in a subassembly, this compound with a hardness of 90 Shore A, is available in addition to the company's already successful 70 and 80 shore A materials.

Fluid connections, including tube fittings in static or mobile hydraulics, are often of a conical design so a connection is maintained under high pressure.

To make sure of sealing integrity, these seals have a small cross section compared with their large diameter and manufactured of NBR, which has good elongation properties.

They are designed to elongate in the seal groove between 5 and 17% to secure their position.

Hydraulic tube fittings are usually stored as ready to use subassemblies, with the seals fitted in an elongated state.

When stored, the seals will suffer ozone attack and standard NBR shows signs of cracking, especially when stored at high temperatures.

To solve this problem, Busak + Shamban set out to develop a range of NBR sealing materials with high ozone resistance.

The new ozone resistant NBR, with a hardness of 90 Shore A is available in addition to 70 and 80 Shore A compounds.

They all have the same benefits as a standard NBR; an operating temperature (depending on media) of -30 to +100C, good mechanical properties, resistance to mineral oil and grease and excellent elongation characteristics.

Also, the material shows no ozone cracking when tested to DIN53509-1.

In this test, samples are tested in an ozone concentration of 0.5ppm when elongated by 20% for 120 hours at a temperature of 40C and humidity of 55% (all percentages at a tolerance of +/-2%).

The new 90 Shore A material is available as standard O-rings.

The 70 and 80 Shore A material can be manufactured as O-rings and custom moulded parts.

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