(1) Shut-off valve
This type of valve is open and closed. Standing on the inlet and outlet of cold and heat sources, equipment inlet and outlet, pipeline branch line (including riser), can also be used as drain valve and bleed valve. Common shut-off valves include gate valves, globe valves, ball valves, and butterfly valves.
Gate valves can be divided into open and dark rods, single and double gates, wedge gates and parallel gates. The tightness of the gate valve is not good, and the opening of the large-diameter gate valve is difficult; the size of the valve body is small along the flow direction, the flow resistance is small, and the nominal diameter of the gate valve is large.
The shut-off valve is divided into three types according to the flow direction of the medium straight flow, right angle type and direct current type, and there are clear poles and dark poles. The shut-off valve is tighter than the gate valve, the valve body is long, the flow resistance is large, and the maximum nominal diameter is DN200.
The spool of the ball valve is an open-hole ball. The plated valve stem is fully open when the spherical opening is facing the axis of the pipe, and is fully closed by 90°. The ball valve has a certain adjustment performance, and the closing is tight.
The valve spool of the butterfly valve is a circular valve plate that rotates along the vertical axis of the vertical pipe axis. When the plane of the valve plate coincides with the axis of the pipe, it is fully open; when the plane of the ram is perpendicular to the axis of the pipe, it is fully closed. The butterfly valve body has a small length and a small flow resistance, which is higher than the price of the gate valve and the globe valve.
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