Cast Steel Piston Valve – Flanged PN40

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Piston valves are used to stop the flow of fluid into a particular area of the system. Therefore, proving essential for maintaining the safety of your system. Due to the unique design of the piston valve, isolation is not affected by media impurity. It is our belief, the piston valve is the safest and best isolation valve to be used on steam and condensate systems.


  • Slow Opening – This helps to stop water hammer. The valve has a cage unit fitted in which the piston moves, creating a variable orifice by degree as opposed to simply ‘open or closed’
  • Tight Shut Off – The BSI classification for leakage rate is IV (0.01% of rated capacity). The Piston Valve has a reliable seal between piston and seal, meeting these requirements.
  • Can Be Maintained In-line – The replacement of the piston rings can be carried out in-line by removing the yoke, leaving the body seals and cage in-line. The top seal is removed, the cage unit taken out, the bottom seal removed and new seats simply installed in reverse order.
  • No Leaks To The Atmosphere – Because the top ring has the same leakage classification as the bottom ring the chances of leakage are as good as or better than bellows-sealed valves.
  • No Wiredrawing On Seating Face – The valve seals on the sides of the piston and not on the flat face. Therefore, wiredrawing cannot occur on the seating face.
  • DIN 2533 – The valve’s ‘face to face’ complies with DIN standards and can fit any comparable DIN valve
  • Not Affected By Flow Direction – The valve can therefore be used under or over the piston. However, we generally advise that the flow be used under the piston to assist with opening.

Additional information

Weight N/A


DiameterDN15 (1/2") - 200 (8")
Temperature-10C - 400C
MaterialGJL250 Cast Iron
0.7040 Ductile Iron
1.0619 Cast Steel
1.4408 Stainless Steel
Connection (DIN)Flanged
Socket Weld


DN15 – 50 (BSP)
DN15 – 50 (Flanged)
DN65 – 200 (Flanged)