Glandless spool

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. Over the years, nitrile seals have proved satisfactory. In addition to nitrile (soft seal) valve ranges, Norgren produces a range of ISO Standard valves with 'glandless spool' technology. The glandless valves use 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 are hardened to 62-70 Rockwell C.

The teflon coating enables the valve to run unlubricated in high cycling applications. Alternatively, the valve can remain unoperated 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. As the spool and sleeve are manufactured from light alloy, they offer lower inertia and fast response. Being of balanced spool design it can be used in multi-pressure applications and vacuum control applications such as packaging and material handling using vacuum cups.