Threaded, welded, or bolted joints in the body enable it to receive inlet and outlet piping, and resist the fluid pressure loads as well. Different connections connect different control valve parts together and different designs enable the application of diverse nozzles and connection types suitable for specific needs.

Direct acting pressure limiting relief valves are fast acting and should be used to: • Protect fixed displacement pumps and directional control.

profile of the fluid pressure is shown in Figure 3-1. The slight pressure losses in the inlet and outlet passages are due to frictional effects. The major excursions of pressure are due to the velocity changes in the region of the vena contracta. Figure 3-1: Pressure Profile of Fluid Passing Through a Valve Control Valve Sizing Sizing & Selection 3

There are various types of valve including sequence, unloading and low pressure relief valves, all of which are operated by a pressure rise in the circuit, 

1. Size pressure control valves (PCV) to perform properly over the entire flow duty envelope. 2. Size a matching pressure safety valve (PSV) capable of handling a pressure control valve

Automatic pressure relieving device actuated by the static pressure upstream the valve. It is suitable for use as either a safety or relief valve, depending on 

pressure when control valve is in operation, Pneumatic tu should have an allowance in bend (use specialized tool) and bands should bind parallel tubing. • Only qualified persons should do electric work in accordance to electrical facility engineering standards. • Cable connections should be made to conform to the facility's conditions.

RELIEF VALVES Remote Control / Direct Type Pilot Operated / Solenoid Controlled Instructions / Hydraulic Fluids PRESSURE CONTROLS CAUTION When making 

The following steps can be followed for simplified Control Valve Sizing: STEP #1: Define a maximum allowable pressure drop for the valve. STEP # 2: Calculate the valve coefficient (Cv) STEP # 3: Preliminary valve selection. STEP # 4: Check the Cv and stroke percentage at the minimum flow.

Modulating Ball Valve $ 93.16 $ 101.66 $129.45 Total Balancing Cost plus VBN Ball Valve per Coil $302.10 $319.61 $368.81 VRN Modulating Pressure Independent Control Valve $232.10

25/03/13 5 POCLAIN HYDRAULICS Hydraulic components - Pressure control valvesDirect operated valves Pilot operated valves PRESSURE RELIEF VALVE VVP (NG 6, 10) • NG 6,