What are the working principles and types of gate valves?

The opening and closing part of the gate valve is the gate. The movement direction of the gate valve is perpendicular to the flow direction. The gate valve can only be fully opened and fully closed, and can not be adjusted and throttled. There are two sealing surfaces in the gate valve. The wedge angle of the two sealing surfaces of the most commonly used gate valve varies with the valve parameters, which is usually 5 ° and 2 ° 52 'when the medium temperature is not high. The rigidity of the gate can be made into a wedge, which can make up for the deviation in the process of processing. 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 is pressed to the valve seat on the other side to ensure the sealing of the sealing surface, which is self sealing. Most gate valves are forced to seal, that is to rely on external force to force the gate to the valve seat to ensure the sealing of the sealing surface. Gate valve gate valve with the stem to make a linear movement, known as rising stem gate valve, also known as rising stem gate valve.  Generally, there are trapezoidal threads on the lifting rod. Through the nut on 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 the operating thrust. When the valve is opened, when the lifting height of the gate is equal to 1:1 of the valve diameter, the fluid passage is completely unblocked, but this position cannot be monitored during operation. In actual use, the top of the valve stem is used as a mark, that is, the position where it can not be opened is taken as its full open position. In order to consider the locking phenomenon of temperature change, the valve is usually turned back 1 / 2-1 turn after opening to the top position. Therefore, the full open position of the valve is determined by the position of the gate, that is, the travel distance. In some gate valves, the stem nut is set on the gate, and the hand wheel turns to drive the valve stem to rotate, so as to lift the gate valve. This kind of valve is called the rotary rod gate valve, or the Non rising stem gate valve.

Type of gate valve

There are many manufacturers of gate valve in China, and the connection size is not uniform. It is mainly divided into the following categories: 1. Mechanical standard valves produced according to JB / t2203-1999 "gate valve structural length"; 2. National standard valves produced according to GB / t12221-2005 "structural length of metal valves"; 3. American Standard valves produced according to ASME b16.10-2009 "face to face and end-to-end dimensions of valves". Gate valve is divided into wedge type and parallel type according to the structure of gate. Wedge gate has three kinds of structure: single ram, double ram and elastic ram.

According to the different structure types, gate valve is divided into flat gate valve and knife gate valve.

Working principle of manual gate valve: turn the hand wheel, and lift or lower the valve plate connected with the valve stem by turning the hand wheel and the thread of the valve stem to open and close.

According to the classification of shell / body material, gate valve can be divided into:

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

Metal valve body lining valve: such as rubber lined valve, fluorine lined valve, lead lined valve, plastic lined valve, enamel lined valve.

Non metallic material valve: such as ceramic valve, glass valve, plastic valve.