A Globe Valve is a valve that moves the closing member (valve) along the centerline of the valve seat and has a very reliable cut-off function. As the cut-off valve flap between the opening and closing of the small, sealing surface can withstand multiple opening and closing, so it is suitable for frequent switching occasions.
The use of cut-off valve is very common, but because of the large opening and closing torque, the length of the structure is longer, usually nominal pass are limited to 250mm below, there are to 400mm.
The use of special attention to the direction of import and export, generally below 150mm cut-off valve medium mostly from the bottom of the valve flow, close the operating force is greater than open, and more than 200mm stop valve medium mostly from the top of the valve into the open operation force is greater than closed The This is due to the closing torque of the valve. In order to reduce the opening or closing torque, more than 200mm cut-off valve can be set within the bypass valve or bypass valve.
The most obvious advantages of the globe valve are:
1. Open height is generally only 1/4 of the diameter of the seat passage, and therefore much smaller than the gate valve.
2. In the opening and closing process, because the valve flap in the valve body sealing surface friction between the valve than the small, so wear.
3. Usually in the valve body and the valve only one sealing surface, so the manufacturing process is better, easy to repair.
Gate valve opening and closing parts is the gate, the direction of movement of the gate and the fluid direction perpendicular to the gate valve can only be fully open and fully closed, not suitable for regulation and throttling.
The valve stem shaft and the valve seat sealing surface perpendicular to the stem open or close the stroke is relatively short, cut valve valve once in the open condition, and its valve seat and sealing surface between the no longer contact, And has a very reliable cutting action, making the cut-off valve products suitable for the media as a cut or adjust and throttling use. Once the stop valve is in the open state, there is no contact between the valve seat and the sealing surface of the valve, so the sealing surface of the sealing valve is less mechanical wear. Since most of the valve seat and valve flap are easy to repair or replace the sealing element without the need to remove the entire valve from the pipeline, which for the valve and pipeline welding into one place is very suitable. The flow direction of the medium through such a valve has changed, so the flow resistance of the valve is higher than other valves.
The most obvious advantage of the cut-off valve is that during the opening and closing process, the friction between the valve flap and the sealing surface of the valve body is smaller than that of the gate valve. The opening height of the Globe Valve is generally only 1/4 of the diameter of the seat passage and is therefore much smaller than the gate valve. Usually in the valve body and valve only one sealing surface, and thus manufacturing process is better, easy to repair.
The principle of selection of cut-off valve is:
1, high temperature, high pressure medium pipe or device should use the cut-off valve. Such as thermal power plants, nuclear power plants, petrochemical systems on the high temperature, high pressure pipeline.
2, cut-off valve used in the pipeline on the flow resistance on the strict management of the pipeline. That is, the pressure loss is not considered much place.
3, small valve can choose needle, instrument valve, sampling valve, pressure needle and so on.
4, there are flow regulation or pressure regulation, but the regulation accuracy is not high, and the pipe diameter is relatively small, such as the nominal through the ≤ 50mm on the pipeline, should use the cut-off valve.
5, synthetic industrial production of small chemical fertilizer and large chemical fertilizer should use the nominal pressure PN160 nominal pressure 16MPa or PN320 nominal pressure 32MPa high pressure angle valve or high pressure angle throttle. 6, alumina Bayer production of the desilicon workshop, easy to coke on the pipeline, easy to use the valve body separately, the seat can be, the carbide seal of the DC-type cut-off valve or DC throttle.
7, the city in the construction of water supply, heating works, the nominal through the smaller pipelines, optional Globe Valve, balance valve or plunger valve, such as the nominal through less than 150mm on the pipeline.