What are the commonly used valve plate types for gate valves?

How about the American Standard Gate Valve? This question cannot be generalized and should be analyzed according to your specific situation. Here is a brief introduction to the characteristics of the American standard gate valve for your reference.

Light weight: The body is made of high-grade ductile black cast iron, which is about 20% 30% lighter than the traditional gate valve, and is easy to install and maintain. Flat-bottomed gate:

The traditional gate valve is often accumulated in the groove at the bottom of the valve due to foreign objects such as stones, wood, cement, iron filings, sundries, etc., which is easy to cause water leakage phenomenon due to the inability to close tightly. Overall rubberization: The ram is made of high-quality rubber for the whole inner and outer rubber, and the European rubber vulcanization technology makes the vulcanized ram able to ensure accurate geometric size ,...

There are four types of valve plates commonly used in gate valves: rigid wedge single gate, elastic wedge single gate, wedge double gate and parallel double gate. No matter what kind of ram, the wedge-shaped structure is used to generate sufficient sealing specific pressure, and the sealing specific pressure increases with the continuous tightening of the handwheel, so the sealing of the gate valve is the most reliable. However, there is a narrow groove between the two seats of the gate valve, and when it is used for viscous, solid particles or easily crystallized and solidified media, the gate may not be completely closed due to the obstruction of the medium remaining in the groove.

The rigid wedge single ram has a simple structure, but when the processing error of the valve plate is large, it is easy to have a loose seal due to the poor self-adjustment adaptability. In addition, due to the poor adaptability of self-adjustment, the ram is easy to be pinched when applied at high temperatures. For valves DN40 and below, rigid wedge single gate valves are generally selected.

The structure of elastic wedge single ram is more complex than that of rigid single ram, but it is simpler than wedge double ram and parallel double ram, and has a certain self-adjusting adaptability, so it is the first choice for DN50 and above gate valves.

The wedge-type double ram is an improved type of elastic single ram, which increases the self-adjusting adaptability of the ram. However, the complex structure also increases the production cost of the valve.

Compared with the other three types of rams, the biggest feature of the parallel double ram is that the friction and wear generated by the wedge structure when it is closed are transferred to the non-sealing surface, thereby eliminating or reducing the wear of the sealing surface, improving the sealing effect of the ram, and increasing the service life of the valve. However, the ram type is the most complex, and the ram size is larger, so that the valve can no longer be produced according to the short series size, and the valve ** increases by 20% to 30%.

Here are some of the well-known brands recognized in the valve industry, which are widely recognized and have a high reputation. While rankings may vary depending on time and market conditions, the following brands are generally considered to be among the top brands in the valve industry:

The following influential first-line brands of water system valves and industrial valves can be used as a reference, but for reference only: Suzhou Neway Valve, Shanghai Guanlong Valve, Shanghai Qizhong Valve, Sanhua, Su Yan, Shentong, Su Valve, Nanfang, Jiang.

First, the word Yao. The above manufacturers are only estimates and references, and the specific situation may vary or fluctuate at any time due to changes in a series of factors such as changes in the market, the size of the competition pattern, and the stability of product quality. As an indispensable key device in industrial production and civil facilities, the quality and reputation of the valve brand directly affect the satisfaction and trust of users.

These brands are known in the valve industry for their innovative technology, high-quality products and reliability. It is important to note that the market and industry are evolving rapidly, and different rankings may vary depending on time and region. For the most up-to-date ranking information, it is recommended to refer to industry reports, professional organizations or market research data for more detailed and accurate information.

Classification by stem:

According to the stem type, it can be divided into open rod gate valve and dark rod gate valve. The valve stem is the operating part of the gate valve, and its function is to transmit the opening and closing force to the opening and closing parts.

1. The trapezoidal thread of the valve stem of the open rod gate valve is placed outside the valve body, located at the upper part of the valve stem, and the valve stem is driven to drive the gate plate to rise and fall synchronously by rotating the valve stem nut to realize the opening and closing of the valve.

It is easy to identify the opening and closing status of the valve to avoid misoperation. Because the stem nut is outside the body cavity, it is conducive to lubrication, and the opening and closing state is intuitive and obvious, so it is widely used. But in harsh environments, the stem.

The exposed threads are susceptible to damage and corrosion, and even affect operation. Its disadvantage is that the height of the valve after opening is large, and a stroke is usually added on the basis of the original height of the valve, so it requires a lot of operation.

as space. 2. The dark rod gate valve is also called the rotary rod gate valve (also known as the dark rod wedge gate valve), the stem nut is placed inside the valve body, in direct contact with the medium, and is often fixed on the ram. The stem is screwed by the rotation of the stem.

The mother drives the ram to do a lifting movement to complete the opening and closing. Usually there is a trapezoidal thread at the bottom of the stem, and through the thread at the bottom of the valve and the guide groove on the disc, the rotational motion becomes a linear motion.

It is the conversion of the operating torque into the operating thrust. Because the trapezoidal thread for transmission is located inside the valve body, it is susceptible to medium corrosion and cannot be lubricated, and the degree of opening cannot be directly observed, so it needs to be equipped with another indicator.

Place. However, its valve stem does not do lifting movement, and the required operating space is small, so it is suitable for occasions with limited location and dense pipelines.

Classification by structure:

According to the structure type, it can be divided into two types: wedge gate valve and parallel gate valve. That is, the gate plate is called a wedge gate valve, and the gate plate is parallel to the plate gate valve.

1. The sealing surface of the flat gate valve is parallel to the vertical centerline, so the sealing surface on the valve body and the ram is also parallel to each other. The most common type of gate valve is the double gate type, in order to close the valve body and the gate.

The two sealing surfaces are in close contact, and double-sided thrust wedges are often used to clamp between the two rams. It is mostly used in low-pressure pipelines such as small pipelines. Parallel gate valves also use a single gate, but it is rare.

2. The wedge gate valve is a gate valve in which the sealing surface is at a certain angle to the vertical centerline, that is, the two sealing surfaces are wedge-shaped. The gate of the wedge gate valve is both single and double. The advantage of the double ram type is that it is sealed and angled.

The accuracy requirements are low, the temperature change is not easy to wedge the ram, and the gasket can be compensated for the wear of the sealing surface. The disadvantage is that the structure is complex, easy to stick in dry media, and more importantly, after the upper and lower baffles are corroded for many years.

The ram is easy to fall off.

Other ways to classify:

According to different standards: national standard gate valve, American standard gate valve, German standard gate valve, Japanese standard gate valve.

According to the connection method: flange gate valve, welded gate valve, threaded gate valve (also divided into internal thread, external thread).

According to the pressure level: high-pressure gate valve, low (medium) pressure gate valve.

According to the driving mode: electric gate valve, pneumatic gate valve, manual gate valve.

Classified by material: stainless steel gate valve, forged steel gate valve, cast steel gate valve, carbon steel gate valve, cast iron gate valve, copper gate valve (also divided into bronze gate valve, brass gate valve), ceramic gate valve, plastic gate valve.

Common types of gate valves are:

Gray iron gate valve: including gray iron open rod gate valve and gray iron dark rod gate valve, this kind of gate valve is suitable for municipal construction, water treatment, water supply and drainage, water conservancy engineering and other fields.

Ductile iron gate valve: usually a soft seal gate valve, also divided into open rod and dark rod, this kind of gate valve is mainly used in sewage treatment, building fire protection, water supply and drainage engineering and other municipal engineering pipelines.

Gray iron and ball valve gate valves are cast iron smell valves, this kind of gate valves are mostly used in room temperature and low pressure pipelines, and the medium is mostly water.

Carbon steel, stainless steel gate valves: these two kinds of gate valves are mostly used in high-temperature and high-pressure pipelines, and the medium is mostly steam, oil, etc., and the application fields are petroleum, chemical, metallurgy, etc.

Knife gate valve: suitable for various liquid fluids such as pulp, slurry, sewage, powder, syrup, coal slurry, ash, slag and water mixture.

Gate valve classification. Gate valve is a gate valve with opening and closing parts, the direction of movement of the gate is perpendicular to the direction of fluid, and the gate valve can only be fully opened and closed, and cannot be adjusted and throttled. The gate valve is sealed by the contact between the valve seat and the ram, and usually the sealing surface will be surfacing with metal materials to increase wear resistance, such as surfacing 1Cr13, STL6, stainless steel, etc. The gate has a rigid gate and an elastic gate, and according to the different gates, the gate valves are divided into rigid gate valves and elastic gate valves.

The gate plays an important role in the sealing of the gate valve, and the gate valve can be divided into wedge single gate gate valve, elastic gate valve, double gate gate valve and parallel gate valve.

Characteristics of different gate valves.

1) Wedge single gate gate valve.

The structure is simpler than that of elastic gate valves;

At higher temperatures, the sealing performance is not as good as that of elastic gate valves or double gate valves;

It is suitable for high-temperature media that are prone to coking.

2) Resilient gate valve.

It is a special form of wedge single ram. Compared with the wedge gate valve, the sealing performance is good at high temperature, and the ram is not easy to be stuck after heating; It is suitable for steam, high-temperature oil and oil and gas and other media, and is suitable for parts with frequent switching.

3) Double gate gate valve.

The sealing performance is better than that of the wedge gate valve, such as the oblique angle of the sealing surface and the fit of the valve seat are not very accurate, it still has better sealing;

After the sealing surface of the ram is worn, the metal pad at the bottom of the spherical top core can be replaced with a thicker one, and it is generally not necessary to surpass and grind the sealing surface, which is difficult to do with a single ram and elastic ram.

There are more parts than other forms of gate valves;

In addition to being suitable for steam, oil and other media, it is also suitable for the parts with frequent switching and the medium with large wear on the sealing surface, and should not be used for the medium that is easy to coke.

4) Parallel gate valve.

The tightness is worse than that of other forms of gate valves;

It is suitable for media with low temperature and pressure;

In addition to the ram that is equipped with a fixed plate on two rams is not easy to fall off, the ram that fixes two rams with lead wire is easy to fall off, and the use is unreliable.

The processing and maintenance of the sealing surface of the gate plate and valve seat is simpler than that of other forms of gate valves.

According to the sealing surface configuration, it can be divided into wedge gate valve and parallel gate valve, and wedge gate valve can be divided into: single gate type, double gate type and elastic gate type; Parallel ram type gate valves can be divided into single ram type and double ram type. According to the thread position of the stem, it can be divided into two types: open rod gate valve and dark rod gate valve.

Gate valves: wedge gate valves, lifting rod gate valves, rotary rod gate valves, quick opening and closing gate valves, reducer gate valves, parallel plate gate valves.

Commonly used into: open rod gate valve and dark rod gate valve Zhengzhou butterfly valve factory.

Types of gate valves.

1.It can be divided according to the structure of the ram.

In the parallel gate valve, the structure with thrust wedge is the most common, which has a double-sided thrust wedge in the middle of the two gate plates, and this kind of gate valve is suitable for low-pressure small and medium-diameter (DN40-300mm) gate valves. There are also springs between the two rams, and the springs can generate tight force, which is conducive to the sealing of the rams.

2) Wedge gate valve: the sealing surface is at a certain angle to the vertical centerline, that is, the two sealing surfaces are wedge-shaped. The inclination angle of the sealing surface is generally 2052,3930,5.

8。，10。The size of the angle mainly depends on the temperature of the medium.

Generally, the higher the operating temperature, the larger the angle should be taken to reduce the possibility of wedge in the event of temperature changes. In the mode gate valve, there are single rams, double rams and elastic rams. The single gate mode gate valve has a simple structure and reliable use, but it has high requirements for the accuracy of the sealing surface angle, which is difficult to process and maintain, and the possibility of wedge is great when the temperature changes.

Double gate mode gate valves are mostly used in water and vapor medium pipelines. Its advantages are: the accuracy of the sealing surface angle is low, the temperature change is not easy to cause the phenomenon of wedge, and the gasket can be added to compensate when the sealing surface is worn.

However, there are many parts of this structure, which are easy to bond in viscous media and affect the sealing. The main thing is that the upper and lower baffles are easy to rust when used for a long time, and the ram is easy to fall off. The elastic gate wedge gate valve, which has the advantages of simple structure and reliable use of single gate wedge gate valve, can produce a small amount of elastic deformation to make up for the deviation generated in the processing process of the sealing surface angle, and improve the manufacturability, has been widely adopted.

2.According to the structure of the valve stem, the gate valve can be divided into.

1) Open rod gate valve: the stem nut is on the valve cover or bracket, and when the gate is opened and closed, the stem nut is rotated to realize the lifting of the valve stem. This structure is beneficial to the lubrication of the valve stem and has a clear degree of opening and closing, so it is widely used.

2) Dark rod gate valve: the stem nut is in the valve body, which is in direct contact with the medium. When opening and closing the gate, it is achieved by rotating the valve stem.

This structure should be equipped with an opening and closing indicator to indicate the degree of opening and closing. The disadvantage of this structure is that the stem thread not only cannot be lubricated, but also directly accepts the erosion of the medium and is easily damaged.

2. If the diameter of the channel in a valve body is not the same (often the diameter at the valve seat is smaller than the diameter at the flange connection), it is called the diameter shrinkage. The diameter shrinkage can reduce the size of the part, reduce the force required to open and close the part accordingly, and at the same time expand the application range of the part. But after the diameter shrinks.

The loss of fluid resistance increases. Under certain operating conditions in certain sectors (e.g. pipelines in the oil sector), valves with reduced bore are not permitted. On the one hand, this is to reduce the resistance loss of the pipeline, and on the other hand, it is to avoid the obstacle caused by the shrinkage of the bore to the mechanical cleaning pipeline.