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For services where common elastomers are unsuitable, Keystone offers an improved design KeyChem, oriented to chemical, pharmaceutical, cosmetic and food industries. The accurate machining of all valve components, and the combination of safety precautions in the shaft area provide a drop-tight seat sealing and a positive gastight shut-off through the shaft area to atmosphere.
Valve Type: Isolation
Sub-Type: Keystone Butterfly Valves
- Two-piece elastomer backing of the PTFE liner assures a positive contact and tight seating of the disc.
- The liner provides flange sealing.
- A one piece thin disc stem lined with 3 mm moulded PFA providing high Kv values.
- Liner and disc are the only two valve parts in contact with the medium.
- Primary shaft sealing by preloaded contact between disc and liner hub. The pressure to keep the sealing surfaces together is provided by an upper and lower coil spring.
- Secondary shaft seal by oversizing the shaft diameter in relation to the shaft hole in the liner.
- Vacuum tests with helium have been performed successfully with pressures less than 20 Pa absolute (0.2 mbarA).
- Wafer and lugged split body design.
- Integral body locating holes to ease installation and to ensure perfect centering of the valve between flanges.
- Integral actuator flange acc. ISO 5211.