A rotary valve, in its simplest form comprises three main elements. A body, a rotor, and a drive system.
One essential element in the trouble-free running of a rotary valve is maintaining the seal around each end of the rotor shaft where it passes through the end covers. Most valves use a simple sealing arrangement comprising gland packing, under pressure within a machined recess in the end cover, sometimes known as the stuffing box.
Gland packing is a square section rope manufactured using a range of materials to best suit the application.
The most common type of packing in rotary valves is PTFE which has good low temperature characteristics and offers low friction properties. Other gland packing materials are utilised for differing applications such as high temperatures or hygienic/food applications.
By installing multiple rings of packing within the gland housing and then pressurising them by means of a simple gland follower an effective seal is achieved around the rotor shaft. Properly installed gland packing prevents product passing through the end cover and wear due to erosion is largely eliminated.
It is essential that the gland packing is under enough pressure to achieve an effective seal and that it has not degraded.
The pressure on the gland packing is achieved by adjusting the gland follower such that it moves towards the end cover, exerting pressure on the packing. Once the gland follower has been adjusted to its physical limit, it is critical that the packing is replaced.
Most incidents of product leakage from a valve or wear to rotor shafts will be through the incorrect maintenance of gland packing.
Rotolok stock a range of gland packing for all applications including high temperatures and food grade packing, across all valve sizes.
We also stock replacement gland followers.
If you have any questions regarding gland packing or other aspects of valve maintenance please contact our Sales team.