In industrial production, the valve is a common control flow rate of the equipment, at the time of using ss gear pump installation, also often use the valve, the commonly used valve globe valve, butterfly valve, ball valve and gate valve is no stranger to many use, but for the globe valve, butterfly valve, ball valve and gate valve: what are the advantages and disadvantages of it?
Choose appropriate valve in use is correct:

One, stop valve
Refers to the closure (disc) along the seat center line of the valve.
According to this movement of the disc, the seat opening changes in direct proportion to the disc stroke.
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, usually in the valve body and disc only a sealing surface, so the manufacturing process is better, easy to maintain;
During opening and closing, the friction force between the disc and the sealing surface of the valve body is smaller than that of the gate valve, so it is wear-resistant.
2, the opening height is generally only 1/4 of the valve seat channel, so it is much smaller than the gate valve;
3, because its packing is generally a mixture of asbestos and graphite, so high temperature grade.
General steam valves are globe valves.
Disadvantages:
1. The flow direction of the medium through the valve changes, so the small flow resistance of the globe valve is higher than that of most other types of valves;
2. Due to the long stroke, the opening speed is slower than the ball valve.

Second, the 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. Low flow resistance (actually 0);
In the larger pressure and temperature range, can achieve a complete seal;
Because not stuck at work (in the absence of lubricant), it can reliably used in the corrosive medium and low boiling point liquid;
2, compact structure, light weight, it can be considered for low temperature medium system reasonable valve structure;
3. Reliable sealing of working medium on both sides;
Symmetrical valve body, especially welded valve body structure, can well withstand the stress from the pipeline;
4, the closing parts can withstand the high pressure difference when closed.
All welded body ball valve, which can be directly buried underground, make the valve internal parts from erosion.
5. Quick opening and closing can be realized, and the opening and closing time of some structures is only 0.05-0.1s, so as to ensure that it can be used in the automation system of the test bed.
When opening and closing the valve quickly, there is no impact.
6. The spherical closing part can be automatically positioned at the boundary position;
When fully open and fully closed, the sealing surface of the ball and the seat is isolated from the media, so the media passing through the valve at high speed will not cause erosion of the sealing surface;
Disadvantages:
1, because the ball valve is the chief seat sealing material of ptfe, it is to almost all the chemicals are 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 to cold flow and poor thermal conductivity, require that the design of seat seals must be built around these characteristics.
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 ℃.
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).

Three, gate valve:
Gate valve refers to the closure (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, fully open or fully closed use.
In general, gate valves cannot be used as a flow adjustment.
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. Low fluid resistance;
When fully open, the sealing surface is less eroded by working medium than the globe valve;
2. Small opening and closing torque required;
Can be used in the medium flow in both directions of the ring network pipe, that is, the direction of the medium is not restricted;
3. Simple shape and structure, good manufacturing performance;
The length of the structure is relatively short.
Disadvantages:
1. Long opening and closing time, large shape size and opening height, large space for installation;
2, in the opening and closing process, the sealing surface person relative friction, friction loss is large, even in high temperature is easy to cause abrasion phenomenon;
3. Generally, gate valves have two sealing surfaces, which adds some difficulties to processing, grinding and maintenance.