Why is the straight stroke valve stem finer?

2017-01-05

It involves a simple mechanical principle: sliding friction is large, rolling friction is small. Straight stroke valve stem up and down movement, packing slightly pressed a little, it will be very tight valve stem, resulting in a larger hysteresis. To this end, the stem is designed to be very small, the filler is often a small friction coefficient of PTFE filler, in order to reduce the hysteresis, but the problem is sent stem fine, easy to bend, filler life is short. To solve this problem, the best way is to use the travel valve stem, that is, the angle of the class of control valve, and its stem stem straight stroke than 2 to 3 times, and the choice of long life graphite packing, stem stiffness Well, the filler life is long, the friction torque is small, the hysteresis is small.