A Comparison of Gate Valves and Other Valves

Valve variety is complex. As one of the valves, what advantages and disadvantages of the gate valves? What are the superiorites of gate valves compared with other valves? How to select gate valves? In this article, we will provide you with the advantages and disadvantages of gate valve in comparison with other valves and the commonly used gate valve selection introduction.

1. Basic introduction of gate valves
The gate valve is a valve that moves along the straight direction of the center line of the valve body flow path and achieves the purpose of opening and closing. It is mainly used for blocking and is widely used.

2. Advantages and disadvantages of gate valves in comparison with other valves
Compared with check valves, the gate valve has small flow resistance, small opening and closing force, small structural scale and reliable sealing. However, it is easy to form a closed valve cavity when the gate valve is closed, so it is not suitable for the medium affected by the ambient temperature for boosting the secondary gasification. The gate valve should not be used to regulate the flow, and the check valve can be used for short-term rough conditioning.

Compared with ball valves, the flow resistance of gate valves is larger and it can not be made of fabric, and it is not suitable for ball passing, slow opening speed. However, gate valves have features of light weights, small opening and closing force, reliable sealing, convenient operation and protection, low prices and simple processing.
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Compared with butterfly valves, the flow resistance of the gate valve is small. It owns small opening and closing force, reliable seal and low processing requirements. The opening speed is slow. The weight is light. And the valve chamber is simple to accumulate liquid gas. Gate valves are cheap, but more expensive than soft sealed butterfly valves.
 

3. General description of the gate valve selection
(1) The first choice of valves for pipeline blocking
(2) It is not suitable for viscous medium, medium containing solid particles, and medium that may be gasified and pressurized in low temperature medium environment.
(3) It is not suitable for ball passing environment (except full bore gate valves).
(4) It is not suitable for fabric.
(5) There will be residual medium in the valve chamber, so it is highly toxic and highly corrosive medium needs to be vented and drained.
(6) Soft sealing gate valves are often used for blocking water systems.

4. Model selection of common gate valves
(1) Rising stem soft seal gate valves (Z41X / RRHX)
(2) Non rising stem soft seal gate valves (Z45X / RVHX)
(3) Cast steel gate valves (Z41H)
(4) Knife gate valves (PZ73H, PZ73X)
(5) Flat gate valves

Rising stem soft seal gate valves (Z41X/RRHX): It is also known as the rising stem elastic seat seal gate valve. The gate is made of cast iron or ductile iron with rubber lining. Suitable temperature is less than 80 degrees. It has good sealing performance and it is not rusty. It is mainly used in water system without device height limit: fire pipe, common water supply and drainage pipeline, building environment and other normal temperature and normal pressure water medium.

Non rising stem soft seal gate valves (Z45X/RVHX): the main performance advantages and disadvantages are the same as the rising stem soft seal gate valve, but in the selection of non rising stem, there is no need for device height requirements. It is used to replace rising stem soft seal gate valve. The feature of non rising stem gate valve is that the thread of the stem is not easily lubricated, so the rising stem soft seal gate valve is still the main product.

Cast steel gate valves (Z41H): they have high temperature and high pressure resistance, chemical, petroleum and other industrial pipeline blocking valve preferred. Large diameter cast steel gate valve is widely used, and electric cast steel gate valve is generally used (ordinary cast steel gate valve with electric actuator).

Knife gate valves (PZ73H, PZ73X): there are two kinds of soft seals and hard seals. The gate is of knife edge shape, and it is specially suitable for blocking viscous media. Generally, the media are pulp, wood pulp, gold ore powder, tailings, fibers, dust, chemical treatment sewage, sedimentation tank, ore, slag, slime, asphalt, silo outlet, fruit, grain, cement slurry, slaughterhouse wastewater, etc.

Flat gate valves: the sealing part  or gate is a sliding valve with parallel gate. It is mainly suitable for transporting and cutting off medium on oil pipeline, natural gas pipeline and urban gas pipeline network. The flat gate valve is related to the occasions with high requirements for working conditions, so the structure is relatively complex. According to different working conditions, there will be different structures.