Both
flow valves,Globe valveand gate valve have similar external housing but operational
functions of both differ little. The main difference between globe and
gate valve is in the form of the inner
elements and the form of the flow inside the both valves . Globe valve has very good
throttling ability while gate valve is not used for throttling.Gate valve is
best suited for isolation and globe valve is best suited for regulating or
throttling the flow.
Globe
valve cannot seal tight as compared to gate valve.Gate valve has tight shut-off ability in pipe lines.Because of this tight shut-off ability of gate valve,it is used upstream of globe valve.You might have seen this gate andglobe valvecombination at the discharge pipe of pumps.
Globe
valve requires greater torque to operate as compared to gate valve.This greater
power requirement for globe valve is also considered when designing automatic
and motor operated actuators for valves.
Gate
valve is not designed to regulate flow ,and if done so then we observe noise
,vibration and seat / disk damage in gatevalves.Whileglobe valvecan be
sometimes used for stop start of flow in case of unavailability of gate
valve.Gate valve is generally used for isolation .
Gate
valve can be used in both directions as designs are available for both
directions of flow.Same gate valve can have flow in both directions.While globe
valve has flow direction usually indicated on it and is used in compliance with
that.
Valve
Opening and closing geometry of disk and seat is also a difference between
globe and gate valve. In a gate valve, the closure element is a plate or disk
which travels parallel to the plane of the seat.The gate in a dam is a well
known example. In aglobe valve, the closure element is usually called a
"poppet", and it travels perpendicular to the plane of the seat.
The
globe valve can be repaired in place while nearly all gate valves need to be
removed from the piping system to have leakage problems repaired.
A globe valve can be opened against a high differential pressure, while a gate
valve will bind and cannot be opened. If you try to open against a high DP,
the seat will score and leak.
A
globe valve has a near linear characteristics of Cv vs. % open, while
agate valve has a severe parabolic characteristic and thus cannot be used for
throttling.
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