Piston-style Tom Wheatley

Protect your equipment

Piston-style Tom Wheatley™ check valves protect your pumps and compressors from damaging backflow. The piston check is a simple, dependable design, and these field-proven valves have been in service for decades.

Because of their unique nonslam design and durability, these check valves have provided years of uninterrupted service downstream from reciprocating pumps and compressors, and in other applications where conventional check valve designs would be subjected to excessive wear. They are also suitable for renewable fuels service.

Piston-style Tom Wheatley check valves are especially beneficial where pulsating flow is present. The valve's top-entry design enables easy access and replacement of valve internal parts with reduced downtime.

• Size range: 2–12 in [50–300 mm]
• ANSI Classes 150 to 1500
• API Spec 6D monogram and conformance to ASME B16.34
• Materials of construction that conform to NACE MR0175/ISO 15156
• Canadian Registration Number (CRN) available on request
• Pressure Equipment Directive 2014/68/EU (PED/CE) proof of conformance available on request
• Full open and top mounted
• Controlled piston movement
• Horizontal or vertical service
• Quick opening of piston
• Integral seat
• Soft or metal seated
• RF or RTJ end connections
• Trims available: WCC, LCC, CF8M, and internal coatings

How does the valve work?

In the absence of differential pressure across the valve piston, gravity and spring force cause the piston to rest in the closed position. Pressure applied at the upstream end of the valve lifts the piston off its seat and allows flow. As the piston moves up, gas in the chamber above compresses and its pressure increases, preventing further travel. This pressure is relieved by actuation of a spring-loaded ball check valve installed in the piston, and the piston continues its upward travel. As flow varies, the piston floats up and down within a cylinder.

Should flow cease, gravity and spring force lower the piston. This downward travel causes a vacuum to develop above the piston, inhibiting further downward movement. An orifice installed at the top of the piston permits pressure equalization above and below, enabling the piston to move down until it contacts the seat and creates a bubble-tight seal, which prevents backflow in the line. The ball check valve and orifice also serve to dampen piston slam that can occur because of rapid flow fluctuations.