Docstoc

Gate Valve A

Document Sample
Gate Valve A Powered By Docstoc
					?A gate valve, also known as a sluice valve, is a valve that opens by lifting a round or
rectangular gate/wedge out of the path of the fluid. The distinct feature of a gate valve
is the sealing surfaces between the gate and seats are planar, so gate valves are often
used when a straight-line flow of fluid and minimum restriction is desired.

A gate valve is a type of stopper placed on a pipe system to block flow. These valves
simply prevent the passage of liquid using a wedge that slides in and out of the pipe.
In most cases, the gate valve is designed to be completely opened or completely
closed. As a result, these valves are rarely used as a means of flow control; they
generally just stop flow completely or are unused. Partially closed gate valves may
increase pressure in a system in unpredictable ways or cause vibration in the liquid.

The construction of a gate valve is quite simple. They generally have two threaded
connectors that hook into the pipe system. It is possible for a gate connector to have
more than two connections, but this is very rare. A post, called a bonnet, rises above
the connectors; this area holds the stopping wedge and the mechanism for raising and
lowering it. Lastly, a handle, which controls the rising and lowering of the stopper,
sits on top of the bonnet.

When the handle is turned, it moves the stopper inside the valve. The stopper slides
down into the pipe and blocks liquid from passing. The valve will typically indicate
the position of the stopper on the outside of the valve, or the handle will screw in and
out to show the relative height of the stopper. The valve casing is slightly wider than
the connected pipes, allowing the stopper to totally cover the opening and make it
completely liquid-tight.

The method used to connect the bonnet to the valve has an impact on the use of the
gate valve. If the bonnet is simply screwed on, the valve will work well for light-duty
applications. Bolted bonnets work well for heavy-duty jobs, but cannot be taken apart
for repair or cleaning. Union-bond bonnets may be taken apart easily, but they also
have the highest rate of leaking. The last style is a pressure-sealed bonnet, it works
well in many different environments, but it is also the most expensive style.
-------------------------------------------------------------------------------------------------------
--------------------------------------------------------

The author is associated with IPFonline
 is India's No. 1 Industrial Product Finder. The portal is a veritable storehouse of
information on industrial products/services.

				
DOCUMENT INFO
Shared By:
Categories:
Stats:
views:13
posted:4/23/2011
language:English
pages:1