valves, valve control means is a fluid delivery system, having a cut-off regulation of flow, to prevent reflux, regulation, diversion or overflow relief functions. A control valve for a fluid system, from the simplest to the shut-off valve extremely complex various valves used in automatic control system, which is quite numerous varieties and specifications. Various types of valves for controlling the flow of fluid can be air, water, steam, mud, oil, liquid metals and radioactive media.
1 Valve Category
1, classified by driving method
(1) automatic valve that does not require a driving force, but on the media itself energy to the valve valve action. The reducing valve, steam trap, a check valve, an automatic control valve.
(2) manual valve: by means of a manual valve handwheel, handle, lever, sprockets, the human actuated valve action. When the torque larger valve opening and closing, the gear or worm gear may be provided between the handwheel and the valve stem. If necessary, remote operation may be performed using a universal joint and propeller shaft.
(3) power-driven valve: power-driven valve mayUsing various power sources for driving. Into electric valves, pneumatic valves, hydraulic valves and the like. Electric valves: valve means of the electric drive. Pneumatic valves: valve driving means of compressed air. Hydraulic valve: driven by oil hydraulic pressure valves. In addition there are combinations of the above several driving method, such as a gas – electric valve.
2, classified according to the role and use of
(1) for regulating: regulating valve, throttle valve and pressure relief valve, a pressure regulating medium is its role, the flow rate and other parameters.
(2) Split: such as dispensing valves, three-way valve, steam trap. Its role is assigned, isolated or mixed line of medium.
(3) Safety: such as safety valves, explosion-proof valve, valve or the like accident. A safety valve to prevent the pressure medium lines or devices exceeds a predetermined value, so as to achieve the purpose of security protection.
(4) cut off: such as gate valve, globe valve, plug valve, ball valve, butterfly valve, needle valve, diaphragm valve. Truncated type valve, also known as closed valves, shut-off valve, which role is to connect or disconnect the line of medium.
(5) check: such as a check valve, also known as one-way valve or check valve, the check valve is a kind of automatic valve, its role is to prevent the line of medium back , prevent the pump and the drive motor reversal, and the leakage of the medium in the container. Pump water off the bottom valve also belong to the class check.
(6) special purpose: such as pigging valve, vent valve, drain valve, exhaust valve. The exhaust valve is an essential auxiliary piping system components, widely used in boilers, air conditioners, oil and gas, soild. Often mounted high ground or bend, etc., to exclude excess gas pipeline, to improve the efficiency and reduce energy consumption management of road use.
2. Compressor Valve
valve is an important component of a reciprocating piston compressor, one of the components is easily damaged, which is responsible for the intake and exhaust gas. The valve seat is traditional, valve, spring, valve guard lift composition, bolts or the like, which directly affects the displacement of the compressor, power consumption and reliability of operation.
The compressor valve works
low-pressure stage of the compressor during operation of the intake valve and an exhaust valve mounted to the cylinder head, the lift of 3mm. And the high-pressure stage of the intake valve and the exhaust valve mounted in the valve chamber in the middle of the cylinder. The piston and cylinder diameter are divided into two big small. Above the top of the piston to the low pressure stage of the working space of the cylinder, the cylinder intake air through the filter. The annular space to the middle of the high-pressure stage of the piston working space, the gas discharged from the low-pressure stage is further compressed by the inter-stage cooler into a high pressure stage.
To ensure safety, the low pressure stage and high pressure stage are respectively provided with a safety valve, the opening pressure of the safety thereof, respectively, than the rated discharge pressure of about 15 high percentages and 10 percentages. The motor rotates the crankshaft through the flexible coupling device, and then the connecting rod, piston pin driving piston reciprocates up and down within the cylinder. When the piston moves from the top dead center to the bottom dead center, the air compressor in the intake process, the intake valve spring is compressed at this time, downward movement of the valve plate, whereupon the intake valve opens, suction gas. Piston return row, i.e. when upward movement from the bottom dead center, the intake valve begins to close, i.e., the elastic force of valve spring by its movement to the upward valve seat seal location.
When the intake and exhaust valves are closed, the piston continues to move upward, the gas in the cylinder is compressed, the pressure rises to the discharge pressure, the upward movement of the exhaust valve valve opened compression spring, compression process ends. After opening the exhaust valve, the cylinder pressure is about the size of the discharge pressure remains constant until the piston top dead center row, all of the gas is discharged, the end of the discharge process. Valve open position is limited by the maximum lift limiter.