Type D Pressure Reducing Valve

The Type D pressure reducing valves are high performance valves specifically designed to optimise the stringent requirements of the fluids handling industry. Principal features include high capacity, balanced internal parts which permit fluctuating inlet pressures and ensure a stable downstream pressure. Tight shut off results under no flow conditions. The Type D, by virtue of its inherent advanced design, yet simplicity, and a minimum of moving parts, provides maximum service life, reliability and accuracy of control. The Type D is also a WRAS - Approved Product, in sizes two and half inch to six inch.

Valves are supplied in sizes half inch to six inch in SG Iron, Bronze, Stainless Steel or materials to suit the process requirements, with ends screwed female or alternatively flanged to customers requirements. Inlet pressures of up to 20.0 Barg can be accommodated, reduced pressure ranges of 0.35 - 13.8 Barg are possible. The maximum working temperature of the type D is 100 Degrees C

All valves are supplied with a nitrile disc and seals for liquids as standard, but other materials are available on request.

High pressure fluid is admitted to the inlet port and acts both on the seat disc and smaller, lower piston areas, which are collectively balanced and therefore unaffected by any initial pressure variations. Compression of the spring opens the seat disc and permits the flow of fluid to the downstream pressure side of the valve, and through a cast internal port to the upper, larger piston chamber. At this point, the reduced pressure acts upon the upper piston area, creating an upward force, which opposes the downward spring load. Therefore, when the force of the reduced pressure in the upward direction exceeds the adjusted spring opening load, the seat disc tends to close, so restricting fluid flow through the valve and reducing its pressure until the desired set pressure is restored by the two forces in balance. Conversely, if the reduced pressure should fall, the spring load would be dominant and the seat disc would open, to permit a greater volume of fluid to flow until the set reduced pressure is reached and maintained at the valve outlet port. Compressing the spring increases the reduced pressure, relaxing the spring decreases the reduced pressure. 

All valves should be fitted in a horizontal pipeline with, flow in the direction of the arrow cast on the side of the body. The adjusting screw should be directly above or below the pipeline. The pipe must
be clean and free from dirt, scale, etc. It is advisable to fit a stop valve on the high pressure side of the line. A relief valve should always be fitted where dead end conditions apply.

Type_D_reducing.pdf