Globe valve, also known as a cut-off valve, belongs to the mandatory sealing type valve and is a kind of cut-off type valve. The connection is divided into three kinds: flange connection, screw connection, and welding connection.
This type of cut-off globe valve valve is very suitable for cutting off or regulating and throttling. Because this type of valve stems opening or closing stroke is relatively short, and has a very reliable cut-off function, but also because of the changes in the valve seat orifice and the valve flap stroke into a proportional relationship, is very suitable for the flow rate of regulation.
The globe valve is designed with a low inlet and high outlet, aiming to make the flow resistance small and save labor when opening the valve. At the same time, when the valve is closed, the valve shell and valve cover between the gasket and the packing around the valve stem are not subject to force and, are not to be subjected to media pressure and temperature for a long time by the role of the service life can be extended to reduce the chance of leakage. In addition, this can also be replaced or added in the state of valve closure packing, easy maintenance.
Under normal circumstances, the globe valve is low in high out, but there are some special circumstances in, which the globe valve is high in low out.
1.Diameter greater than 100mm high-pressure globe valve.
Due to the large diameter valve sealing performance is poor, in the shut-off valve when the medium pressure acts on the valve flap, thereby improving the sealing performance of the valve.
2. Two globe valves in series in the bypass pipeline, the globe valve requires a "high inlet and low outlet".
In order to ensure. In order to ensure the sealing of the valve in a maintenance cycle, the need for frequent opening and closing operations of the valve requires the configuration of two tandem shut-off valves.
3. Boiler exhaust and exhaust globe valve
The boiler exhaust and exhaust globe valve are only used in the boiler startup and water supply process, The opening and closing frequency is small, but often due to poor sealing caused by the loss of work quality. Therefore, in order to improve the sealing of some power plants, these shut-off valves are installed in the direction of “high inlet and low outlet”.
4.Electromagnetic shut-off valve.
Electromagnetic shut-off valve is a fast shut-off and rapid cut-off of fuel supply. The structure of the solenoid shut-off valve is similar to that of a globe valve. If the solenoid shut-off valve is also a working medium from the lower part of the entry, from the upper part of the outflow, the fuel has a great force of the lower solenoid shut-off valve flap and the weight of the solenoid shut-off valve is much smaller than it.
Therefore, if the working medium enters the quick stop valve from the lower part, the torque generated by the weight is less than the torque generated by the fuel pressure. When the quick disconnect valve is actuated, the fuel cannot be cut off for the intended purpose.
If the working medium enters from the upper part of the quick stop valve, once the quick stop valve is actuated, the pressure behind the valve drops rapidly and the fuel force acting on the lower part of the valve flap drops to zero very quickly, while the fuel acts on the valve flap and the force formed by the weight of the hammer and the gravity of the lever.
In general, the valve is difficult to close when low inlet and high outlet are used in large diameter and high pressure. If the low inlet and high outlet are used under high pressure and large diameter, the valve stem will be easily deformed and bent for a long time under the water pressure, affecting the safety and sealability of the valve. Safety and sealing; if you choice of a high inlet, or a low outlet, you can reduce the diameter of the valve stem, for manufacturers and users to save costs.
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