TYPES OF VALVES (II)

Valves are used in a wide variety of applications. Valves have different requirements according to their types and uses, mainly including sealing, strength, regulation, circulation, opening and closing. Here are a few common industrial valves.

 

1. Diaphragm Valve

This is a clamped valve with an elastic diaphragm. The screw is connected to the compression member, and the compression member is operated by the valve stem to move up and down. When the compression piece rises, the diaphragm is raised and the channel is created. When the compressor drops, the diaphragm is pressed on the body of valve or at the bottom of the contour. This valve is not only suitable for switching and throttling, but also for transporting corrosive and viscous fluids such as mud, food, pharmaceuticals, woven adhesives, etc. Because the valve's operating mechanism is not exposed to the transport fluid, so it is not polluting and the stem packing portion is unlikely to leak.

 

2. Safety Valve

The safety valve is used as an overpressure protection device on pressurized equipment such as boilers and pressure vessels. When the pressure of the medium in the protected equipment rises abnormally to the specified value, the valve automatically opens and then discharges in full to prevent the pressure from continuing to rise. When the pressure drops to another specified value, it automatically closes. In factories, the opportunity to use high-temperature and high-pressure gas is quite large. The pressure vessels or equipment are damaged due to abnormal pressure, and the probability of fire or explosion is quite high. In order to prevent such accidents and make the process operate steadily, according to the American Society of Mechanical Engineers (ASME), the safety valves must be installed in all high-voltage equipment.

3. Butterfly Valve

The structure of this valve is based on the principle of the tube retaining plate. Its flow control element is a gate with a dip angle. The gate is fixed on the mandrel, and it can be controlled by opening and closing with a rotatable mandrel. The valve seat can be made of metal, rubber, Teflon and other materials, and it is fixed on the valve body. The valve is simple in structure, its valve body is the wafer type and light weight.It is especially for large flow control.

 

4. Pressure Reduction Valve

The pressure reduction valve is a kind of regulating valve. It reduces the inlet pressure to a required outlet pressure through the throttling of the opening and closing member. It can keep the outlet pressure basically unchanged by using the energy of the medium itself when the import pressure and flow rate change.

5. Steam Trap

The steam trap is a valve used in steam pipe networks and equipment to automatically discharge condensed water, air and other non-condensable gases, and prevent water vapor leakage.

 

6. Throttle Valve

The throttle valve is a commonly used shut-off valve that is mainly used to connect or cut off the medium in the pipeline, and it is generally not used to regulate the flow. The throttle valves are suitable for a wide range of pressure and temperature, but they are generally used in medium and small caliber pipelines.

 

In the design and selection of valves, besides the basic parameters and performance, the performance of fluids, including the phase state, corrosiveness and viscosity of fluids, should also be considered.