There are many types of valves, each has its own advantages and disadvantages, the following small series of five valve advantages and disadvantages, including gate valve, butterfly valve, ball valve, globe valve and plug valve, I hope to help you.

Gate valves

Gate valve refers to the closure parts (gate) along the channel axis of the vertical direction of the movement of the valve, in the pipeline is mainly used as a cutting medium, that is, full open or full closed use. In general, gate valve can not be used as a flow regulation. It can be used at low or high temperatures, depending on the valve material. But gate valves are generally not used for conveying mud and other media in the pipeline.

Advantages:

(1) small fluid resistance;

(2) small opening and closing torque required;

(3) can be used in the medium flow in both directions of the ring network pipe, that is to say, the flow direction of the medium is not limited;

(4) when fully open, the sealing surface by the working medium erosion than the globe valve is small;

(5) the body structure is relatively simple, the manufacturing process is better;

6 structure length is relatively short.

Disadvantages:

(1) shape size and open height is larger, need to install the space is larger;

(2) in the opening and closing process, the sealing surface person relative friction, friction damage is large, even at high temperature is easy to cause abrasion phenomenon;

(3) general gate valve has two sealing surface, to the processing, grinding and maintenance increased some difficulties;

(4) the opening and closing time is long.

Butterfly valve

Butterfly valve with disc type opening and closing a reciprocating swing around 90 ° to open and close and regulating fluid channel of a valve.

Advantages:

(1) structure is simple, small volume, light weight, consumable province, do not use for large diameter valve;

(2) open and close quickly, small flow resistance;

(3) can be used for medium with suspended solid particles, according to the strength of the sealing surface can also be used for powder and granular media. It is widely used in metallurgy, light industry, electric power, petrochemical systems, gas pipelines and waterways.

Disadvantages:

(1) the flow regulation range is not large, when open up to 30%, the flow will enter more than 95%;

(2) due to the structure of the butterfly valve and seal material restrictions, should not be used in high temperature, high pressure pipeline system. General working temperature below 300 ℃, PN40 below;

(3) sealing performance relative to the ball valve, globe valve is poor, so used for sealing requirements is not very high place.

Ball valve

Ball valve evolved by the plug valve, the opening and closing is a sphere, using a sphere around the axis of the stem rotate 90 ° the realization of the aim of opening and closing. Ball valve in the pipeline is mainly used to cut off, distribution and change the direction of medium flow, the design of v-shaped opening ball valve also has a good flow regulation function.

Advantages:

(1) has the lowest flow resistance (the actual is 0);

(2) because it won't stick in the work (in the absence of lubricant), so it can be used reliably in corrosive media and low boiling liquid;

(3) in the larger pressure and temperature range, can achieve complete sealing;

(4) can achieve fast opening and closing, some structure of the opening and closing time is only 0.05~0.1s, to ensure that it can be used in the test bench automation system. Quick opening and closing valve, no impact;

(5) spherical closure can be automatically positioned on the boundary position;

6. The working medium is sealed on both sides reliably;

7 in full open and close, ball and seat sealing surface and media isolation, so high speed through the valve medium will not cause erosion sealing surface;

8, structure is compact, light weight, it can be considered that it is used in the low temperature medium system of the most reasonable valve structure;

9) the valve body is symmetrical, especially the welded valve body structure, and can well withstand the stress from the pipe;

Attending to close the part can bear the high pressure difference when the closure. 2 2 whole welding valve body ball valve, can be buried in the ground directly, so that the valve interior parts are not subject to erosion, the maximum service life of up to 30 years, is the oil, natural gas pipeline the most ideal valve.

Disadvantages:

(1) because the ball valve is the most important seat sealing ring material is ptfe, it is inert to almost all chemical substances, and has a small coefficient of friction, performance stability, not easy to aging, temperature range of application and sealing performance is good comprehensive characteristics. However, the physical characteristics of ptfe, including high expansion coefficient, sensitivity to cold flow and poor thermal conductivity, require that seat seal design must be carried out around these characteristics. Therefore, when the sealing material becomes hard, the reliability of the sealing is damaged. And, of ptfe heat resistance level is low, can only be used under the condition of less than 180 ℃. Beyond this temperature, the sealing material will age. And under the condition of use for a long time, generally only in 120 ℃ is not used.

(2) its regulating performance relative to the globe valve is poor, especially the pneumatic valve (or electric valve).

Globe valve

Globe valve: a valve in which the shutoff (disc) moves along the center line of the seat. According to this form of disc movement, seat opening changes are proportional to disc stroke. Because the stem of this kind of valve opens or closes stroke is relatively short, and have very reliable cut off function, because the change of valve seat mouth and the stroke of valve disc are in direct proportion, suit to adjust to flow rate very much. Therefore, this type of valve is very suitable for cutting or regulating as well as throttling.

Advantages:

(1) in the process of opening and closing, because the disc and valve body sealing surface friction force is smaller than the gate valve, so wear resistance.

(2) open height is generally only 1/4 of the seat channel, so much smaller than the gate valve;

(3) usually in the valve body and disc only a sealing surface, so the manufacturing process is better, convenient maintenance;

(4) because its filler is generally asbestos and graphite mixture, so the temperature grade is higher. Generally steam valves are globe valves.

Disadvantages:

(1) because the flow direction of the medium through the valve has changed, so the minimum flow resistance of the globe valve is higher than most other types of valves;

(2) because the journey is long, the opening speed is slower than the ball valve.

cock

Cock: refers to the rotary valve to close a pillars plug, make through 90 ° rotating valve plug of the access point is separated from the body is same or spilling, realize the opening or closing a valve. The plug may be cylindrical or conical in shape. Its principle and ball valve are basically similar, ball valve is developed on the basis of plug valve, which is mainly used in oil field exploitation, but also used in petrochemical industry.

Advantages:

1, used for regular operation, open and close quickly, light.

2. Low fluid resistance.

3, simple, relatively small volume, light weight, easy to maintain.

4. Good sealing performance.

5, limited by the direction of installation, the flow direction of media can be arbitrary.

6. No vibration and low noise.

Disadvantages:

1, cover is too large, resulting in too much torque, not flexible.

2. Due to the influence of body weight, the diameter is limited.

3, in actual use, if the use of large size valve, you must use the inverted cock structure, easy to affect the sealing effect.