Views: 266 Author: Site Editor Publish Time: 2020-10-06 Origin: Site
Many sewage treatment equipments are needed in sewage treatment, among which valve is an important one. There are many kinds of valves suitable for sewage treatment. This paper mainly introduces the usage and characteristics of some valves such as gate valve and globe valve, etc.
It is one of the most commonly used open and close valves. The gate is to connect (fully open) and cut off (fully closed) the medium in the pipeline by using the gate (i.e. the gate, in the gate valve, the opening and closing parts are called the gate, and the valve seat is called the gate seat). It is not allowed for throttling. It should be avoided to slightly open the gate in usage, because the erosion of high-speed flow medium will accelerate the damage of sealing surface.
① The flow resistance is small.
② It is easier to open and close.
③ It has high height and long opening and closing time.
④ Water hammer is not easy to occur due to long closing time.
⑤ The medium can flow in any direction on both sides, which is easy to be installed.
⑥ The length of the structure (the distance between the two connecting ends of the system housing) is small.
⑦ The sealing surface is easy to wear, which affects the service life.
⑧ The price is more expensive.
Globe valve is a closed-circuit valve which uses valve clack(the closing part of the stop valve) to move along the center line of the valve base (valve seat) channel to control the opening and closing of the pipeline. The globe valve is generally suitable for conveying liquid and gas medium under various pressure and temperature conditions within the specified standard range, but it is not suitable for conveying liquid containing solid precipitation or precipitated crystal. In the low-pressure pipeline, the globe valve can also regulate the flow of medium in the pipeline. Due to the limitation of structure, the nominal diameter of globe valve is less than 250mm. If the medium pressure is high and the flow rate is high, the sealing surface will wear quickly. Therefore, when the flow needs to be adjusted, a throttle valve must be used.
① The abrasion and scratch of the sealing surface are not serious, so the work is reliable and the service life is long.
② The area of sealing surface is small and the structure is simple. The man hour required for manufacturing sealing surface and precious materials required for sealing ring are less than those for gate valve.
③ When the valve is opened and closed, the travel of the valve clack is small, so the height of the globe valve is small. It is easy to operate.
④ It will not cause sudden opening and closing phenomenon, and it is not easy to cause‘water hammer’phenomenon to move the valve clack by screw thread.
⑤ It is difficult to open and close with large torque.
⑥ The flow resistance is large.
⑦ The structure is complex.
⑧ The flow direction of the medium is unidirectional. The medium flows from the bottom up.
Butterfly valve is a rotary valve which turns about 90 ° or 90 ° or so with disc type (also known as butterfly plate) opening and closing parts to open and close the passage. The movement of butterfly valve clack is of wiping property, so most butterfly valves can be applied for medium with suspended solid particles.
① It has the advantages of small overall dimension, short length, simple structure and light weight.
② It is easy to operate and quick to open and close, only rotating the valve clack 90 ° for opening and closing.
③ The sealing and adjusting performance is good.
④ The operating torque and fluid resistance are small.
⑤ Due to the limitation of sealing material, the range of operating pressure and temperature of butterfly valve is small.
The check valve is to prevent the backflow of medium in the pipeline. It is opened when the medium flows in the same direction and automatically closed when the medium flows in the opposite direction. It is generally applied in pipelines that do not allow the medium to flow in the opposite direction, so as to prevent the counter current medium from damaging the equipment and parts. When the pump stops running, it will not cause the rotary pump to reverse. In pipeline, check valve and closed-circuit valve are often used in series. This is due to the poor sealing of the check valve. When the medium pressure is small, there will be a small part of the medium leakage. A closed-circuit valve is required to ensure the pipeline is closed.
The pressure reducing valve is to reduce the medium pressure in the equipment container or pipeline to the specified pressure. it can still maintain the outlet pressure within a certain range when the inlet pressure changes and the flow outlet changes. The pressure reducing valve achieves the pressure reduction with flow control, so that it is suitable for the needs of various production processes.