2006-12-25 15:44:51 · 3 answers · asked by uriel 1 in Science & Mathematics ➔ Engineering
Gate valves are not designed for throttling. They are designed to restrict fluid flow. The higher the pressure on the closure element, the tighter it seats itself, the better it restricts. Needle valves on the other hand are.
2006-12-25 16:35:02 · answer #1 · answered by RScott 3 · 1⤊ 1⤋
The gate in a gate valve is tapered slightly and may also have movable cheeks (The sealing surfaces on the gate) which are pushed against the body (seat) sealing surfaces by a wedge when the valve is closed.
Gate Valves are not designed for throttling and should be either fully open or fully closed.
Because of the taper and wedging action the clearances between the gate and seat are quickly lost as the gate is opened slightly. Because of this loose fit a throttled gate valves gate would chatter (flop back and forth) in the turblent flow generated by the fluid passing under the gate. This chattering would cause rapid wear in the valve.
2006-12-25 17:52:44 · answer #2 · answered by MarkG 7 · 1⤊ 0⤋
Because response time is too slow compare with buterfly or ball.
2006-12-25 16:13:27 · answer #3 · answered by VPT 2 · 1⤊ 1⤋