a check valve is a device that only allows the flow of fluids in one direcey have twports, one as ae media and one as the output for the media. since they only allow media flow in one direction, they are commonly referred to as ‘one way valves valves. The main purpose of a check valve is to prevent backflow in the system Figure 1 shows an example of a check valve A check valve relies on a pressure differential to work. They require a higher pressure on the ut side of the valve than the output side to open the valve When the pressure is hig utlet side(or the input side pressure is not high enough), the valve will close. Depending on the valve type, the closure mechanism is different. Unlike other valves, they do not need a handle ever actuator. o an to correctly workey are commonly installed in applications that backflow would cause an issue. However since they are non return valves, they are a cheap, effective and easy solution to solve a
potential issue. Backflow can cause an issue if the backflow is contaminated, and therefo contaminat media upstream For example, a sewer line will have a non return valve ensure that waste can leave but not re-enter the syster
ey are also used It bacKFlow w
cause damage to equipment upstream that can only allow media
W
example, a reverse osmosis filter can only have water pass through it in one direction, so a one
way valve is installed downstream to prevent this. There are various sizes, designs, and materia
How does a check valve work?
Cracking Pressure
a check valve requires a
(p
curs is called the check valve ‘crackir
specific cracking pressure changes based
ze, so ensure that your system can generate this cracking pressure and that it is suitable
applicatIo
Closing
ever falls below the cracking pressure or there is a back pressure(flow attempting to move fror
will close. Depending on the check valve design, the closing mechanism can change. In short, the back pressure pushes a gate, ball, diaphragm, or disc against
the orifice and seals it. Depending on the design the closing process can be assisted by a s
nstallation Orientation
As a one way valve only works in one direction
crucial to know the correct installation orientation. often times, there is an arrow on the valve housing
e flow direction otherwise you will need to examine the valve to ensure it is installed in the intended flow direct
it is backwards flow will not be
able to move through the system and a build-up of pressure could cause damage
