New material with optimised ozone resistance from Busak+Shamban

New material with optimised ozone resistance from Busak+Shamban

New material with optimised ozone resistance from Busak+Shamban

Busak+Shamban makes available a good value NBR materialdeveloped to give optimised ozone resistance, helping to stopcracking when seals are stored in an elongated state in asubassembly.

A hydraulic equipment manufacturer told us about seal leakage onsystems fitted to excavators after a very hot summer. There hadbeen no previous problems and the cause was found to be ozonecracking.A hydraulic equipment manufacturer told us about seal leakage onsystems fitted to excavators after a very hot summer. There hadbeen no previous problems and the cause was found to be ozonecracking.

Fluid connections, including tube fittings in static or mobilehydraulics, are often of a conical design so a connection ismaintained under high pressure. To make sure of sealing integrity,these seals have a small cross section compared to their largediameter and manufactured of NBR, which has good elongationproperties. They are designed to elongate in the seal groovebetween 5% and 17%, to stop movement.Fluid connections, including tube fittings in static or mobilehydraulics, are often of a conical design so a connection ismaintained under high pressure. To make sure of sealing integrity,these seals have a small cross section compared to their largediameter and manufactured of NBR, which has good elongationproperties. They are designed to elongate in the seal groovebetween 5% and 17%, to stop movement.


Hydraulic tube fittings are usually stored as ready to usesubassemblies, with the seals fitted in an elongated state. Whenstored, the seals will suffer ozone attack and standard NBR showssigns of cracking, especially when stored at high temperatures. Tosolve this problem, Busak+Shamban set out to develop a NBR sealingmaterial with high ozone resistance.

Illustration shows typical subassembly with O-Ring fitted

The new ozone resistant NBR, with a hardness of 70 Shore A, gives all the benefits of a standard NBR; an operating temperature of -30°C to 100°C (depending on media), good mechanical properties, resistance to mineral oil and grease and excellent elongation characteristics. Also, the material shows no ozone cracking when tested to DIN 53509-1. In this test, samples are tested in an ozone concentration of 50 pphm (+/- 5) when elongated by 20% for 120 hours at a temperature of 40°C and humidity of 55% (all percentages at a tolerance of +/- 2%).

The new material is available as standard O-Rings and custom moulded parts.

Footnote: The effect of ozone on elastomer

Ozone is another form of oxygen, where 3 atoms of oxygen, rather than 2, join to form a molecule. Ozone is formed in the air, for example, from discharges produced by electrical equipment. Since it is chemically very reactive, in contact with rubber materials, it causes them to crack, especially when under tension.