The globe valve is a forced sealing valve, so when the valve is closed, pressure must be applied to the disc to force the sealing surface not to leak. When the medium enters the valve from under the disc, the resistance that the operating force needs to overcome is the friction force between the valve stem and the packing and the thrust generated by the medium pressure. Since the force to close the valve is greater than the force to open the valve, the diameter of the valve stem should be larger, otherwise there will be a failure of the valve stem bending.
According to the connection method, it can be divided into three types of globe valve: flange connection, threaded connection and welding connection. Since the appearance of the tight sealing valve, the medium flow direction of the globe control valve has changed from the top of the disc to the valve cavity. At this time, under the action of the medium pressure, the diameter of the valve stem can be reduced accordingly because the pressure to close the valve is small and the pressure to open the valve is high. At the same time, under the action of the medium, the valve is also relatively tight.
Globe valves can be used in heat transfer oil, toxic, flammable, high permeability, polluted environment and radioactive fluid medium pipelines, and can also be used for regulation. All castings for this valve are precision cast. Globe control valve refers to a valve whose closing member (disc) moves along the centerline of the valve seat. According to this movement form of the valve disc, the change of the valve seat opening is proportional to the stroke of the valve disc. The stem of this valve has a relatively short opening or closing process and has a very good interception function. And because the change of the valve seat opening is proportional to the stroke of the valve disc, it is very suitable for regulating the flow. Therefore, this type of valve is ideal for blocking, regulating and throttling, as well as pneumatic valve control ball valves.
(1) Globe valves should be selected for pipelines or equipment of high temperature and high pressure medium. Such as thermal power plants, nuclear power plants, high temperature and high pressure pipelines in petrochemical systems, etc.
(2) The flow resistance of stainless steel globe valves requires a loose pipeline, that is, a local area where pressure loss is rarely considered.
(3) Small valves, such as needle valves, instrument valves, sampling valves, pressure gauge valves, etc.
(4) There is flow adjustment or pressure adjustment, but the adjustment accuracy is not high, and the pipe diameter is relatively small.
(5) Water supply and heating projects in urban construction, as well as pipes with a smaller nominal diameter, such as pipes with a nominal diameter of less than 150mm. All of the above can choose globe control valve, balance valve or plunger valve.