There are many types of valve, each has its own advantages and disadvantages, advantages and disadvantages are listed below small make up the five valves, including gate valve, butterfly valve, ball valve, globe valve and plug valve, hope will be helpful to you.
Gate valves
Gate valve is closed parts (ram) along the channel axis vertical direction valve, mainly for cut off the medium in the pipe on the road, that is fully open or close. In general, gate valves cannot be used as a flow adjustment. It can apply pressure at low temperature can also be applied to high temperature and high pressure, and according to the different material of the valve. But the gate is generally not used for conveying slurry medium in pipeline.

Advantages：


(1) Fluid resistance small;
(2) the opening and closing torque smaller;
(3) can be used in the medium flow in two directions of ring network management way, that is to say, the flow of medium is not restricted;
(4) is wide open, the sealing surface erosion by working medium is smaller than globe valves;
(5) the form structure is relatively simple, manufacture good manufacturability;
(6) structure length is shorter.

Disadvantages：

(1) the dimensions and open height is bigger, installation space is needed;

(2) in the process of opening and closing, the sealing surface relative to the friction, friction losses, even at high temperature easy to cause scratches phenomenon;

(3) general gate valve has two seal face, give adds some difficulties to machining, grinding and maintenance;

(4) opening and closing time is long.

Butterfly valve

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

Advantages:

(1) simple structure, small volume, light weight, consumables, don't be used in large diameter valves;

(2) the opening and closing fast, small flow resistance;

(3) can be used in the medium with suspended solids, based on the strength of the sealing surface can also be used for powder and granular media. Can be used in ventilation and dust removal pipe two-way opening and closing and adjustment, it is widely used in metallurgy, light industry, electric power, petroleum chemical industry system of gas pipeline and channel, etc.

Disadvantages:

(1) flow control range is not big, when open 30%, traffic will be in more than 95%;

(2) because of the limitation of butterfly valve's structure and sealing material should not be used in high temperature and high pressure in the pipeline system. General working temperature below 300 ℃, PN40 below;

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

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 line is mainly used for cutting, distribution, and change the flow direction of medium, the design into a v-shaped opening ball valve has a good flow regulating function.



Advantages：


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

(2) because not stuck at work (in the absence of lubricant), it can be reliably used in the corrosive medium and low boiling point liquid;

(3) in a larger range of pressure and temperature, can realize completely sealed;

(4) can realize the rapid opening and closing, some of the structure of the opening and closing time of just 0.05 ~ 0.1 s, to ensure that can be used to test automation system. No impact on the rapid opening and closing valves, operation;

(5) spherical can close a position automatically locate at the border;

(6). Working medium on the double sealing is reliable;

All landowners in the full open and full closed, the ball and seat sealing surface and the dielectric isolation, so the media does not cause across the valve sealing surface erosion;

End of compact, light weight, can think it is the most reasonable valve used for low temperature medium system structure;

Pet-name ruby body symmetry, in particular welded body structure, well under stress from the pipe;

When attending close thing that can withstand the high pressure difference. ⑾ all welded body ball valve, which can be directly buried underground, make the valve internal parts from erosion, the highest service life can be up to 30 years, is the most ideal valve oil, natural gas pipeline.

Disadvantages：

(1) because the main seat sealing ball valve material is teflon, it is to almost all of the chemicals have inert, and has a small friction coefficient, stable performance, not easy ageing, wide temperature scope and comprehensive characteristics of sealed performance is good. But the physical properties of ptfe, including high expansion coefficient, sensitivity of cold flow and poor heat conductivity, seating requirements of the design must revolve around these features. So, when sealing material hardening, the reliability of the seal is damaged. And, of ptfe heat resistance level is low, can only be used under the condition of less than 180 ℃. More than this temperature, sealing materials will be aging. And under the condition of use for a long time, generally only in 120 ℃ is not used.

(2) it's regulation performance relative to the globe valve is less, especially the pneumatic valve (or electric valve).

Globe valve

Globe valve: refers to the closed (disc) along the valve seat centerline mobile. According to this mobile form of disc, seat and disc change in his itinerary directly proportional relationship. Due to open or close the valve stem travel relatively short, and very reliable cutting function, and due to the change of his seat and disc stroke proportional relationship, is very suitable for the traffic regulation. Therefore, this type of valve is very moving cooperation for cut off or adjust and throttling.

Advantages：

(1) in the process of opening and closing, due to the friction between the disc and body sealing surface is smaller than gate valves, and wear resistance.

(2) the opening height are generally only a quarter for seat channel, so much smaller than gate valves.

(3) typically on the valve body and disc only a sealing surface, thus making craft is good, easy to maintenance;

(4) due to its general for asbestos packing with a mixture of graphite and consequently higher heat resistance level. General steam valves are globe valves.




Disadvantages：

(1) due to the flow direction of medium through the valve changed, so stop valve, the minimum flow resistance is also relatively higher than most other types of valves;

(2) because of a long journey, open the ball valve slowly.

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 shape of the valve plug into cylindrical or conical. The principle is similar with the ball valve, ball valve is developed on the basis of the cock, it is mainly used in oil field drilling, but also used in petroleum chemical industry.

Advantages:

(1) often used for operation, opening and closing fast, lightweight.

(2) small fluid resistance.

(3) simple, relatively small size, light weight, easy to maintenance

(4) good sealing performance.

(5) limited by the installation direction, the flow of medium can be arbitrary.

(6) no vibration, low noise.



Disadvantages：


(1) the cover is too large, resulting in the torque is too big, inflexible.

(2)body weight, diameter size is limited.

(3)In actual use, if use big size valve, it must use cock structure, easy to affect the sealing effect.