Flow regulating valves are also known as speed control valve. The primary function of the flow control valve is flow control in a pneumatic system and regulates the pressure of flow of fluid. Flow control valves in hydraulics are used for controlling the volume of fluid which is supplied to different parts of the hydraulic system.
The speed of the actuators which is being used in the hydraulic circuits can be controlled by regulating the fluid flow, to carry out this regulation operation we need devices and the device which is providing that regulation operation is flow regulation valves.
It is also known as shell. It is used as primary pressure boundary of valve. Everything is being hold together by the framework called valve body. The inlet and the outlet piping is received into it with the help of bolted, welded joints. It is cast into various shapes in which the cylindrical and the spherical is the economical one.
It is the cover provided for the opening in the body of valve. The body is split in two parts which is bolted together. Some valve bonnets used as a valve covers only while some of them are used for support valve internal accessories like actuator, stem and disk.
It is referred to the elements which is present in internal of a valve. It consists of stem, sleeves, seat and disk. The performance of the valve can be ascertain by seat and disk interface.
Disk is a element which allow and restrict the fluid flow. When disk is at closed state then total system pressure is exerted on the disk and the outlet side is depressurized. Seating surface for a disk is provided by the seat.
It is that element which is responsible for the connection of actuator and the disk and keeps the disk in its position. The connection of stem with the disk is done with the help of threaded or welded joints. There are two types of stem non- rising stem and rising stem. In rising stem when valve is open then the stem will rise above actuator. And in case of non rising stem there is not any upward movement of stem.
It is the element by which stem and disk assembly is being operated. It can be operated manually or by electric motor.
This element is used for packing in valves which in result prevents the leakage between stem and bonnet.
1. Plug Valve or Globe Valve:
2. Butterfly Valve:
3. Ball Valve
4. Balanced Valve
Fluid flow can be varied or can be controlled by varying the area through which fluid is passing. When fluid flow is controlled there is pressure drop and this pressure drop is to be considered during selection of a flow control valve. In typical hydraulic circuit there is a pressure fluctuation at the load, sometime higher and sometime lower load. However the inlet pressure is constant, the pump is giving fluid at a constant pressure but the outlet pressure may be different.
To take care of these fluctuations in the load either we can have pressure compensated pumps or we can have pressure compensated flow control valve. Pressure compensated flow control valve can keep the flow rate constant even with the variable load. These pressure compensated flow control valve may have spool and by changing the position of the spool we can change the area of the passage and accordingly the required flow can be maintained during the flow of fluid through the device i.e., control valve.
