What Are Piston Valves?
Piston valves are isolation valves where a precision-machined cylindrical piston moves axially to open or close flow. Unlike gate valves, the piston’s wiper-seal action cleans seating surfaces on every operation — making them ideal for steam, condensate, and wet gas.
PureSys India supplies Spirax Sarco piston valves — globally trusted for steam engineering reliability.
How They Work
The solid piston slides through a PTFE or metal sleeve. Turning the handwheel retracts the piston (open) or advances it to seal against the seat. The wiping action removes scale and deposits on each stroke — a self-cleaning mechanism that eliminates early valve failure in steam service.
Key Features
- Self-cleaning piston: Wipes seat surfaces on every operation
- Full-bore flow: Minimal pressure drop when fully open
- Screwed BSPT/NPT and flanged ends
- Rated for saturated steam up to 32 bar
- In-service gland tightening without plant shutdown
- Bodies in stainless steel, cast iron, and carbon steel
Piston Valve vs Gate Valve in Steam Service
| Feature | Gate Valve | Piston Valve |
|---|---|---|
| Self-cleaning action | No | Yes |
| Suitable for wet steam | Poor | Excellent |
| In-service gland tightening | Limited | Yes |
| Maintenance frequency | Higher | Lower |
Applications
- Steam main isolation and branch connections
- Condensate return lines
- Steam trap bypass valves
- Boiler feed and blowdown lines
Available from PureSys India
View the full Spirax Sarco piston valves range, all isolation valves, or contact our engineers.