Check Valves Types and Terms
Types of Check Valves
- Ball check valves are valves where liquids can flow
only one way. The pressure from the liquid forces the ball to move,
when the pressure from the fluid stops the ball also stops and the
valve closes.
- Clapper valves are a type of check valve used in firefighting. This
valve has a hinged gate (often with a spring pulling it shut) that
will only remain open in the outflowing direction.
- Double check valves consist of at least two independently
acting check-valves. They are typically used in liquid services.
- Foot valves are often used in conjunction with a
pump. The valve aids in pumping water and helps prevent backflow.
- Hydraulic check valves prevent backflow in hydraulic
systems, typically using a ball or a poppet.
- Lift check valves has a disc, sometimes called a lift, that can be
lifted up off its seat by higher pressure of inlet or upstream flow.
A guide keeps motion of the disc on a vertical line, so the valve can
later reseat properly.
- Plastic check valves can be used for industrial
purposes or for lower grade home use, such as in a swimming pool or
aquarium. Typically, they are used when resistance to corrosion is
needed.
- Pneumatic check valves allow fluids to flow in one
or two ways. When the fluid is allowed to flow more than one way it
is often metered.
- Relief valves relieve excess and potentially dangerous
pressure from piping systems or closed-top vessels and are normally
closed until the set pressure is reached.
- Sanitary check valves are used when the fluids contained
in the pipes need to remain germ free. These check valves are often
used for medical, food, or dairy purposes.
- Silent check valves have a spring-operated return mechanism. They eliminate
the shock of sudden reversal of flow, making them a favorite for use
in clear liquid systems.
- Stop check valves are a type of check valve with
override control to stop flow regardless of flow direction or pressure.
When the valve is open, it acts as a check valve, but the valve can
be deliberately shut to stop flow.
- Swing check valves use outside levers to slow down
the flow of materials through a pipe. The lever pulls the disk into
the flow which causes the flow to stop more quickly.
- Wafer check valves are often used for liquid services. The check valve is made
of two half-circle disks hinged together. With positive flow, the two
disks fold together to allow materials to flow through the pipe. With
reverse flow, they retract to a full circle to restrict flow.
Check Valve Terms
- A part of a regulating valve that
converts various forms of energy (electrical, fluid, etc.) into mechanical
motion to open or shut the valve seats.
- A system's reversal of normal flow resulting from
an increase in the downstream pressure exceeding that of the supply pressure.
-The pressure that is the result of a restriction
of the main flow, caused by gravity, pumps, or restrictions on the pipe;
measured in inches H20 or PSI.
- A material that can be stretched or distorted but will
return to its original shape.
- Device used when the material running through
a pipe or a valve is at high or low temperatures. This device helps prevent
damage to the sealing materials.
-Power that is used to provide motion and force to
mechanisms by applying, generating, and controlling pumped or compressed
liquids or gases; this term also encompasses hydraulics and pneumatics.
- A gate valve often found in waste water treatment
plants. It is used to contain fluids.
- A small valve which operates a larger valve with
very little power necessary for use; utilized when the system requires
the no-return characteristic of a valve for only a portion of the cycle.
- Operated or pressurized by air or other gases.
- A device that utilizes pneumatic energy to
regulate or open/close the valve. A spring that is used solely to open
the valve, will normally be fitted inside a valve which allows the valve
to return to the closed position.
- A valve that moves up to or from its seat perpendicularly.
- Makes certain the closing device of the valve stays
in the correct position.
- Pressure difference in a valve between
the inlet and the outlet.
- A quick pressure rise.
- A unit of pressure; equivalent to
the metric unit of Kilonewtons per square centimeter.
- A valve that is able to be inserted into the bottom
of a tank.
- A stationary part of the valve which restricts fluid
or gas flow when it comes in contact with the movable portion of the
valve.