 Check
Valves
A check valve is a mechanical device that allows process fluid
or gas to flow in only one direction preventing fluid or gas backflow.
Categorized as one-way directional valves or non-return
valves, fluid flow in the desired direction opens the valve,
while backflow forces the valve closed. With help from manufacturers
such as Check-All, Valutech offers a complete line of in-line spring
loaded piston type check valves for almost any service application.
When very specific cracking pressures are required, Check-All can
provide customized springs to meet the needs of the customer.
Check Valve Suppliers:
Check-All
Function:
The mechanics of check valve operation are not complicated. Most
check valves contain a ball that sits freely above the seat, which
has only one through hole. The ball has a slightly larger diameter
than that of the through hole. When the pressure behind the seat
exceeds that above the ball, liquid is allowed to flow through the
valve. But once the pressure above the ball exceeds the pressure
below the seat, the ball returns to rest in the seat, forming a
seal that prevents backflow.
Kinds of Check Valves
Check valves use three different means to prevent backflow.
1. Single and Double Disc Swing
2. Ball
3. Plunger
While check valves use a variety of technologies to allow and stem
the flow of liquids and gases, two of the most popular check valve
methods are the: single disc swing and ball-check
valves.
Single disc swing valves are designed with the closure element
attached to the top of the cap. The closure element can be pushed
aside by the flow, but swings back into the close position upon
flow reversal. These valves are not good choices in services with
frequent flow reversal, as the disc is often pounded into the seat
and wears quickly. These valves may be installed vertically or horizontally,
although when mounted vertically a lever and counter-balance should
be applied to reduce the valves tendency to stay open in situations
where flow velocity changes slowly.
Ball-check valves use a free-floating or spring loaded ball
resting in a seat ring as the closure element. Upon reverse flow,
the ball is forced back into its seat preventing backflow. These
valves are good for most services. They can even handle fluids that
produce gummy deposits. Since the disc is free to rotate wear is
distributed evenly and this all helps to keep the valve seats clean.
Plunger check valves use a plunger that is lifted when the
line pressure lifts the plunger thus opening the valve. The flow
is checked in the opposite direction until pilot pressure is applied
to the blind end of the plunger through the pilot connection. This
causes the plunger to unseat the valve spool and oil is allowed
to flow through the valve.
Call us today. Tel: 905.940.0961
or by Email: info@valutechinc.com
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