A sliding stem type control valve actuates in linear motion. A stem comes with a single port or double port arrangement.
Single port means it has only one plug is there to restrict the flow of the fluid and double port means it has two plugs to throttle the flow of the fluid.
Sliding stem type of valve has a travel length of less than 3/4" except in some case it has a travel length requirement of more than 3/4".
Have a look into the below figure to know the difference between two assemblies.
Now have a look at different internal parts of the sliding stem control valve.
Let learn about each part of the sliding stem valve:
1. valve plug stem: It connects the plug with the actuator part and provide strength to the actuator.
2. Packing Flange: It compresses the stud bolt to make the gland packing tight and prevent the process leak.
3. Actuator Yoke Nut: Used to connect the actuator and the valve body stem.
4. Packing: It prevents leakage of the process from the valve body.
5. Bonnet: It supports the position of the plug and prevent it to move left and right.
6. Valve plug: It is the main part of a valve body which is used to restrict the flow of the fluid.
7. Cage: Used to reduce cavitation by reducing the pressure drop around the valve body.
8. Seat ring gasket: It is used to support seat.
9. Valve body: It comprises of the valve plug, trim and valve seat.