Permanent in cold and heat sources, equipment, branch lines (including risers), can also be used as drain valves and vent valves. Common shutoff valves are gate valves, globe valves, ball valves and butterfly valves.
Gate valves can be divided into open bar and hidden bar, single gate and double gate, wedge gate and parallel gate, etc. Gate valve closing tightness is not good, the opening of large diameter gate valve is difficult; along the direction of water flow, the size of valve body is small, flow resistance is small, and the nominal diameter span of gate valve is large.
Globe valves can be divided into three types according to the flow direction of medium: straight-through type, right-angle type and direct-current type, which can be divided into open rod and dark rod. The closing tightness of globe valve is better than that of gate valve. The valve body is long and the flow resistance is large. The maximum nominal diameter is DN200.
The valve core of the ball valve is a round ball with an opening. The plate-operated valve stem makes the sphere opening fully open to the pipeline axis and turn 90 degrees to fully closed. Ball valves have a certain regulation performance and close tightly.