What is a fire gate valve?

What is a fire gate valve?

The opening and closing member of the fire gate valve is the gate, the direction of movement of the gate is perpendicular to the direction of the fluid, the gate valve can only be fully open and fully closed, not for regulation and throttling. The gate has two sealing surfaces, the most commonly used mode gate valve two sealing surfaces form a wedge, wedge angle varies with the valve parameters, usually 50, the medium temperature is not high when 2 ° 52'. Wedge gate valve gate can be made into a whole body, called a rigid gate; can also be made into a gate that can produce a small amount of deformation, in order to improve its craftsmanship, to compensate for the deviation of the sealing surface angle in the process, this gate is called a resilient gate.

 

Classification of fire fighting gate valves.

Types of fire fighting gate valves, according to the sealing surface configuration can be divided into wedge gate type gate valves and parallel gate type gate valves, wedge gate type gate valves can be divided into single gate pole type, double gate type, and resilient gate type; parallel gate type gate valve can be divided into single gate type and double gate type. According to the thread position of the stem, it can be divided into two kinds of open stem gate valve and concealed stem gate valve.

 

Features of fire fighting gate valve.

1, light weight: the valve body is made of high-grade ductile iron, about 20% to 30% lighter than traditional gate valves, and easy to install and maintain.

2, flat bottom gate valve seat: traditional gate valves are often due to stones, wood, cement, iron filings, debris, and other foreign objects in the valve bottom groove siltation phenomenon, resilient seat sealed gate bottom valve with the same flat bottom design as the plumbing machine, not easy to cause debris siltation, so that fluid flow smoothly.

3、Whole package rubber: The inner and outer rubber of the gate is made of high-quality rubber. The first-class rubber vulcanization technology in Europe makes the gate after vulcanization to ensure accurate geometry, and the rubber is firmly connected with the ductile iron gate, not easy to fall off, with good elastic memory.

4、Precision casting valve body: the valve body adopts precision casting, the precision geometry makes the valve body internal without any finishing process to ensure the sealing of the valve.

 

The fire fighting gate valve has the following advantages.

1、Small fluid resistance, sealing surface by the medium of gouging and erosion is small.

2、Effortless to open and close.

3, the medium flow direction is not restricted, not disturbing the flow, not reducing the pressure.

4, simple shape, short structure length, good manufacturing process, a wide range of applications.

 

The disadvantages of the fire gate valve are as follows.

1, between the sealing surface, is easy to cause erosion and abrasion, and maintenance is more difficult.

2, the shape of the larger size, open the need for a certain space, open and close a long time.

3, the structure is more complex.

 

 

The principle of fire gate valve.

When the fire gate valve is closed, the sealing surface can rely only on the medium pressure to seal, that is, rely on the medium pressure to the sealing surface of the gate to the other side of the valve seat to ensure the sealing surface of the seal, which is self-sealing. Most of the gate valves are forced to seal, that is, when the valve is closed, rely on external force to force the gate to the seat, to ensure the sealing surface of the seal.

 

The gate of the fire fighting gate valve with the stem for linear motion is called the lift rod gate valve ( also known as the open rod gate valve ). Usually, there are trapezoidal threads on the lift rod, and through the nut on the top of the valve and the guide groove on the valve body, the rotary motion is changed to linear motion, that is, the operating torque is changed to operating thrust.

When opening the valve, when the gate is raised to a height equal to 1:1 times the valve diameter, the passage of fluid is completely open, but this position cannot be monitored during operation. In actual use, the top point of the valve stem is used as a marker, i.e., the position of open immobility, as its fully open position. In order to take into account the locking phenomenon of temperature changes, it is usually opened to the apex position and then reversed 1/2-1 turn, as the fully open position of the valve. Therefore, the valve's fully open position, according to the position of the gate (i.e., stroke) to determine.

In some gate valves, the stem nut is located on the gate, the handwheel rotation drives the stem rotation, and the gate lifts, this valve is called a rotary rod gate valve or concealed rod gate valve.

 

Fire gate valve structural features.

The general gate valve used in the market for a long time is generally leaky or rusty phenomenon, the enterprise introduced the European high-tech rubber and valve manufacturing technology produced by the resilient seat seal gate valve, overcome the general gate valve sealing poor, rust and other defects, resilient seat seal gate valve use the resilient gate plate to produce a trace of elastic deformation compensation effect to achieve a good sealing effect, the valve has a light switch, reliable sealing, good elastic memory, and The valve has the significant advantages of a light switch, reliable sealing, good elastic memory and service life. Can be widely used in water, sewage, construction, petroleum, chemical, food, medicine, light textile, electric power, ships, metallurgy, energy systems, and another body pipeline as a regulating and intercepting device.

 

The installation and maintenance of the fire gate valve should pay attention to the following matters.

①Handwheel, handle and transmission mechanism are not allowed to be used for lifting, and collision is strictly prohibited.

② Double gate valve should be installed vertically (i.e., the stem is in a vertical position, handwheel at the top).

③ gate valve with bypass valve should be opened before opening the bypass valve (to balance the pressure difference between the import and export and reduce the opening force).

④Gate valve with transmission mechanism should be installed according to the product instruction manual.

⑤ If the valve is frequently opened and closed, lubricate it at least once a month.

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