1.Why is the double seat valve easy to oscillate when working at a small opening?
For a single core, when the medium is a flow-open type, the valve stability is good; when the medium is a flow-closed type, the valve stability is poor. The double-seat valve has two spools, the lower spool is in the flow closure, and the upper spool is in the flow opening. In this way, when working with a small opening, the flow-spool type spool will easily cause the valve to vibrate. The reason why it cannot be used for small openings.
2.Why can't the double seal valve be used as a shut-off valve?
The advantage of the double-seat valve spool is the force-balanced structure, which allows a large pressure difference, and its prominent disadvantage is that the two sealing surfaces cannot be in good contact at the same time, resulting in large leakage. If it is used artificially and compulsorily for cut-off occasions, it will obviously not work well. Even if many improvements are made for it (such as double-sealed sleeve valve), it is not desirable.
3.Which straight-stroke electric control valve has poor anti-blocking performance, and angular stroke valve has good anti-blocking performance?
Straight stroke valve spool is vertically throttled, and the medium is flowed in and out horizontally. The flow path in the valve cavity must be turned upside down, which makes the flow path of the valve quite complicated (like an inverted "S" shape). In this way, there are many dead zones, which provide space for the precipitation of the medium, which will cause clogging if it continues for a long time. The direction of the angle travel valve is the horizontal direction. The medium flows in horizontally and flows out horizontally. It is easy to take away the dirty media. At the same time, the flow path is simple and there is little space for the medium to settle.
4.Why is the stem of straight travel regulating valve thin?
It involves a simple mechanical principle: large sliding friction and low rolling friction. The stem of a straight-stroke valve moves up and down, and the packing is slightly compressed, and it will wrap the stem tightly, resulting in a large return difference. For this reason, the valve stem is designed to be very small, and the packing is usually a tetrafluoro packing with a small friction coefficient in order to reduce the backlash. However, the problem stemmed from this is that the valve stem is thin, it is easy to bend, and the packing life is short. The best way to solve this problem is to use a travel valve stem, which is an angle-stroke control valve. Its stem is 2 to 3 times thicker than a straight-stroke stem, and it uses a long-life graphite filler. Well, the filler has a long life, but its friction torque is small, and the return difference is small.
5.Why is the cut-off pressure difference of the angular stroke valve large?
The cut-off pressure difference of the angular stroke type valve is large because the torque generated by the combined force of the medium on the valve core or the valve plate to the rotating shaft is very small, so it can withstand a large pressure difference. [The above contents are organized and released for you by the valve electric device ]
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