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The Gate Valve view
valve
The gate valve is a general service valve used primarily for on - off, non-throttling service.
The
valve is closed by a flat face, vertical disc, or gate
that slides down through the valve to block the
flow.
The Globe Valve view valve
The globe valve effects closure by a plug with a flat
or convex bottom lowered onto a matching horizontal seat located
in the center of the valve. Raising the plug opens the valve, allowing fluid flow. The globe valve is used for on - off
service and handles
throttling applications.
The Pinch Valve view valve
The pinch valve is particularly suited for applications
of slurries or liquids with large amounts of
suspended solids.
It seals by means of one or more flexible elements, such as a rubber tube, that can be pinched to shut off flow.
The Diaphragm Valve view valve
The diaphragm valve closes by means of a flexible diaphragm attached to a compressor. When the compressor is lowered by
the valve stem onto a weir, the diaphragm seals and cuts off flow. The
diaphragm valve handles corrosive, erosive
and
dirty services.
The Needle Valve view valve
The needle valve is a volume-control valve that restricts flow in small lines. The fluid going
through the valve turns
90 degrees and passes through an orifice that is the seat for a rod with a cone-shaped tip. The size of the orifice is
changed
by positioning the cone in relation to the seat.
In addition to these standard valve products, many valve manufacturers produce custom-designed
valves and actuators for
specific applications.
Valves are available in a broad spectrum of sizes
and materials. Each design has its own
advantages, and selection of the proper valve for particular application is critical. The factors generally
considered
in the selection of a valve include:
- The substance to be handled and the required flow rate.
- The requirement that the valve control and/or shut off the flow in the manner demanded by the service conditions.
- The ability of the valve to withstand the maximum working pressure and temperature.
- The ability of the valve to resist attack by corrosion or erosion.
- Actuator requirements, if any.
- Maintenance and repair requirements.
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The Plug Valve view valve
The plug valve is used primarily for on - off service and some throttling services. It controls flow by means of a
cylindrical or tapered plug with a hole in the center that lines up with the flow path of the valve to permit flow.
A quarter turn in either direction blocks the flow path.
The Ball Valve view valve
The ball valve is similar in concept to the plug valve but uses a rotating ball with a hole through it that allows
straight-through flow in the open position and shuts off flow when the ball is rotated 90 degrees to block the flow
passage. It is used for on - off and throttling services.
The Butterfly Valve view valve
The butterfly valve controls flow by using a circular disc or vane with its pivot axis at right angles to the direction
of flow in the pipe. The butterfly valve is used both for on - off and throttling services.
The Check Valve view valve
The check valve is designed to prevent backflow. Fluid flow in the desired direction opens the valve, while backflow
forces the valve closed.
The Pressure Relief Valve view valve
The pressure relief valve is designed to provide protection from over-pressure in steam, gas, air and liquid lines.
The valve "lets off steam" when safe pressures are exceeded, then closes again when pressure drops to a preset level.
The Control Valve view valve
The control valve is designed to ensure accurate proportioning control of flow. It automatically varies the rate of
flow based on signals it receives from sensing devices in a continuous process. Some valves are designed specifically
as control valves.
However, most types of valves can be used as control valves, both linear and rotary motion, by the addition of power
actuators, positioners, and other accessories.
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Valves
