The flow direction of globe valves
The globe valve is designed for low inlet and high outlet. The purpose is to make the flow resistance small and save effort when opening the globe valve
. At the same time, when the valve is closed, the gasket between the valve housing and the valve cover and the packing around the valve stem are not subjected to force, and will not prolong the service life due to the effects of the medium pressure and temperature, thereby reducing the probability of leakage. In addition, it is also possible to replace or add fillers when the valve is closed to facilitate maintenance.
Many people think that the globe valves are alway low inlet and high outlet, but it is not. In general, the globe valves are low inlet and high outlet, but there are also some special cases where the globe valves are high inlet and low outlet:
1. High pressure globe valve with diameter over 100mm
Due to the poor sealing performance of large-diameter valves, the use of this method shuts the valve in the closed state, the media pressure acts on the valve flap to increase the sealing of the valve.
2. Two globe valves in series on the bypass pipe, and the second one requires high-in and low-out.
In order to ensure the tightness of the valve during a maintenance cycle, valves that are frequently opened and closed require the installation of two series-connected shut-off valves. According to the flow direction of the medium, the bypass stop valves are a primary valve and a secondary valve. When the unit is running normally, the primary valve and the secondary valve are closed, and both are in direct contact with the medium. In order to prevent the packing between the shell and cover, also the one around the stem from being affected by the medium and temperature for a long time, and to replace the packing during operation, the installation direction of the secondary valve requires high in and low out ".