The design of the gate valve makes it ideal for the free flow of fluids. When the gate valve is fully open, the gate is completely drawn into the valve body so that the pressure and flow through the valve is consistent with the connected piping.
What is rising stem and non rising stem globe valve?
Gate valves are divided into vertical stem valves and non rising stem globe valves. non rising stem globe valves have the stem screwed into the gate at the lower end. The stem remains vertical and stationary even when the gate moves up and down. In a rising stem gate valve, the stem is attached to the gate, and the gate and stem rise or fall simultaneously. Gate valves are available in threaded or flanged gate valve designs.
What is the difference between a rising stem globe valve and a non rising stem globe valve?
What is a rising stem valve?
The lifting and lowering screw of the bright stem flange gate valve is exposed, the nut is fixed close to the handwheel (not rotating axial movement), the rotation of the screw and the gate is only relative movement, and there is no relative axial displacement up and down the valve flap and the valve stem together. The lifting screw of the non-exposed stem flange gate valve only rotates and does not move up and down.
Advantages and disadvantages of open stem gate valves.
Easy to open and close.
Small fluid resistance, sealing surface by the media scouring and scouring.
Media flow is not limited, no turbulence, no pressure reduction.
The sealing surface is easy to be corroded and scratched, and maintenance is difficult.
Larger structure requires more space and long open time.
What is a non rising stem valve?
A non rising stem globe valve is an external stem valve, also known as a swing stem gate valve or a blind stem wedge gate valve. In an NRS valve, the stem will rotate to open and close the gate, but the stem does not move up and down as it rotates. As the stem rotates, it moves in and out of the non rising stem globe valve, which also moves the gate to open or seal the non rising stem globe valve.
Advantages and disadvantages of non rising stem globe valve.
Concealed stem valves take up little space and are ideal for gate valves where space is limited. An opening and closing indicator should generally be installed to indicate the degree of opening and closing.
Non-lubricated stem threads can lead to media corrosion and easy damage.