Over the years nitrile seals have proven to be satisfactory. In addition to nitrile (soft seal) valve ranges, Norgren produce a range of ISO standard valves with glandless spool technology.
Most pneumatic solenoid valve manufacturers provide solenoid valves with nitrile seals. The seals are either in the form of o rings, disc seals or bonded to the spool then surface ground.
Norgren’s glandless valves are unique in design in that they utilise a hardened anodised Teflon coated spool and sleeve. The glandless spool and sleeve have no dynamic seals. The spool operates on an air bearing principle that offers several benefits over conventional nitrile soft seal valves.
The spool and sleeve is hardened to 62-70 Rockwell C. The Teflon coating enables the valve to run un-lubricated in high cycling applications. Alternatively the valve can remain un-operated for days.
In these circumstances, condensation from the airline often builds up in the valve. The Teflon coating ensures there is no sticking of the spool on start up (Monday morningitis).
As the spool and sleeve is manufactured from light alloy it offers low inertia and fast response. Being of balanced spool design, the glandless valve can be used in multi pressure applications and vacuum control applications such as packaging and material handling using vacuum cups.