Gate Valves Manufacturers

Gate valve is a gate of opening and closing parts. The movement direction of the gate is perpendicular to the fluid direction. The gate valve can only be fully opened and fully closed, and cannot be adjusted and throttled. The gate valve is sealed by the contact between the valve seat and the gate. Usually, the sealing surface will be overlaid with metal materials to increase the wear resistance, such as overlaying 1Cr13, stl6, stainless steel, etc. There are rigid gate valve and elastic gate valve. According to the difference of the gate valve, the gate valve is divided into rigid gate valve and elastic gate valve.
When the gate valve is closed, the sealing surface can be sealed only by the medium pressure, that is, the sealing surface of the gate valve is pressed against the valve seat on the other side by the medium pressure to ensure the sealing of the sealing surface, which is self sealing. Most gate valves are forced sealed, that is, when the valve is closed, the gate must be forced to the valve seat by external force to ensure the tightness of the sealing surface.

Movement mode: the gate of the gate valve moves linearly with the valve stem, also known as the rising stem gate valve. Generally, the lifting rod is provided with trapezoidal thread. Through the nut at the top of the valve and the guide groove on the valve body, the rotary motion is changed into linear motion, that is, the operating torque is changed into operating thrust. When the valve is opened, when the lifting height of the ram is equal to 1:1 times of the valve diameter, the fluid channel is completely unblocked, but this position cannot be monitored during operation. In actual use, the apex of the valve stem is taken as the mark, that is, the position where the valve stem cannot be opened is taken as its full open position. In order to consider the locking phenomenon caused by temperature change, it is usually turned back 1 / 2-1 circle at the position of the top as the position of fully opening the valve. Therefore, the fully open position of the valve is determined according to the position of the RAM (i.e. the stroke). Some gate valves have valve stem nuts set on the ram, and the rotation of the handwheel drives the valve stem to rotate to lift the ram. This valve is called a rotating stem gate valve or a Non rising stem gate valve.

Gate valves are divided into wedge type and parallel type according to the structure of the gate. Wedge ram has three structures: single ram, double ram and elastic ram.

Gate valves are divided into flat gate valves and knife gate valves according to different structural types.

Working principle of manual gate valve: rotate the hand wheel to open and close the valve plate connected with the valve rod by advancing and retreating the threads of the hand wheel and the valve rod.

According to the classification of shell / main body materials, gate valves can be divided into:

Metal valves: such as carbon steel valves, alloy steel valves, stainless steel valves, cast iron valves, titanium alloy valves, Monel valves, copper alloy valves, lead alloy valves, etc.

Metal body lined valves: such as rubber lined valves, fluorine lined valves, lead lined valves, plastic lined valves and enamel lined valves.

Non metallic valves: such as ceramic valves, glass valves and plastic valves.

advantage

1. The flow resistance is small. The medium channel inside the valve body is straight, the medium flows in a straight line, and the flow resistance is small.

2. It saves labor when opening and closing. Compared with the stop valve, the movement direction of the ram is perpendicular to the medium flow direction whether it is open or closed.

3. High height and long opening and closing time. The opening and closing stroke of the ram is large, and the lifting is carried out through the screw.

4. Water hammer is not easy to occur. The reason is that the closing time is long.

5. The medium can flow in any direction on both sides, which is easy to install. Both sides of the gate valve channel are symmetrical.

6. The structure length (the distance between the two connecting end faces of the housing) is small.

7. Simple shape, short structure length, good manufacturing process and wide application range.

8. Compact structure, good rigidity of the valve, smooth passage, small flow resistance, stainless steel and hard alloy for sealing surface, long service life, PTFE packing, reliable sealing, light and flexible operation.

shortcoming

(1) The general gate valve has two sealing surfaces, and the processing and manufacturing are more complicated than the stop valve

(2) There is relative friction between the sealing surfaces, and the wear is large. It is inconvenient to repair the worn sealing surfaces

(3) The structure size of the valve cavity is large, resulting in long structure length, large overall size and large installation space. The large-diameter gate valve is particularly heavy

(4) Long valve opening and closing time

Parallel double gate valve

Parallel double gate valve

(5) A closed valve chamber can be formed, so a pressure relief structure to prevent abnormal pressure rise in the middle chamber shall be provided when necessary