Globe valve installation direction, installation notes
The current medium of general globe valve such as flows upward from below valve seat, namely the habit is called “low enter above”, such when the valve is closed, the sealing filler of valve stem place does not suffer the action of working medium pressure and temperature, and the valve closes close close below the circumstance, still can undertake filling change the job. Its disadvantage is the valve closing force is large, large diameter valve is difficult to achieve sealing.
Therefore, sometimes also make the medium flow down from the top of the seat, that is, used to be called “high in and low out”, due to the medium pressure on the upper part of the disc, the valve is easy to achieve sealing, but such a valve opening torque is larger, easy to cause the leakage of sealing packing and can not be replaced online valve packing.
In general, the globe valve medium below DN150 mostly flows in from the bottom of the disc, while the globe valve medium above DN200 mostly flows in from the top of the disc, which is caused by considering the closing torque of the valve. In order to reduce the opening or closing torque, generally DN200 above the cut-off valve are set by the inside bypass or the outside bypass valve.
The common practice in the power industry is: nominal pressure ≤ When PN160, generally use “low into higher”; Nominal pressure ≥ When PN200, generally use “high in and low out”.
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