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How To Distinguish Plunger Valve From Globe Valve

Sep 20, 2019

How To Distingguish Plunger Valve From Globe Valve ?

1 . plunger valve is composed of valve body, bonnet, stem, plunger, hole frame, sealing ring, handwheel and other parts. When the handwheel rotates, the valve opens and closes by driving the plunger up and down in the middle of the hole frame. The opening and closing part of the globe valve is a plug-shaped disc, the sealing surface is plane or conical, and the disc moves in a straight line along the center line of the fluid.


2.the closing of plunger valve is composed of a stainless steel plunger, two elastic sealing rings and a metal partition frame, the sealing effect is achieved by the close coordination of plunger and sealing ring, the plunger is inserted in two sealing rings, the sealing area is much larger than that of ordinary globe valve, when the switch plunger valve, the plunger moves slowly in the sealing ring, the contact surface is almost non-wear, when closed, the plunger is inserted into the lower sealing ring and cut off the flow channel. When opened, although the plunger is separated from the lower sealing ring, it is still hidden in the upper sealing ring, keeping it isolated from the outside world and avoiding leakage.


3. 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 below the disc, the resistance that the operating force needs to overcome is the friction force of the stem and packing and the thrust produced by the pressure of the medium. The force of closing the valve is greater than that of opening the valve, so the diameter of the valve stem is larger, otherwise the top bending of the valve stem will occur.

 

4. The globe valve has the following advantages: simple structure, convenient manufacture and maintenance, small working stroke and short opening and closing time. Good sealing, small friction between sealing surfaces, long life. The shortcomings of the globe valve are as follows: the fluid resistance is large, and the force required for opening and closing is large. It is not suitable for medium with particles, high viscosity and easy coking. The adjustment performance is poor. The advantages of plunger valve are said, its biggest disadvantage is the slow opening and closing speed.