Glandless spool for water treatment

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 both low and high cycling applications.

Alternatively, the valve can remain unoperated for many weeks, as happens in some water treatment valve systems. In these circumstances, condensation from the airline can often build up in the valve. In conventional soft seal valves the condensation can cause the seal to swell and stick. In a glandless spool and sleeve, the teflon coating ensures there is no sticking of the spool on start-up.

Additionally, the glandless spool and sleeve are relatively impervious to 'oil carryover' that a compressor might generate.