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Thread: Check Valve - Switch flow calculation

  1. #1
    Associate Engineer
    Join Date
    Mar 2018
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    2

    Check Valve - Switch flow calculation

    I have a check valve (air) that I would like to compute the air flow at which the check valve is activated. It is used to maintain a safe level of vacuum in a system. The valve is normally closed (no air flow) and it is open when the pressure on both sides is equal (vacuum). The spring constant is known so are the diameter on both inlet/outlet orifices. I have no instruments to establish the flow so I would like to solve it mathematically. Any reference, examples will be greatly appreciated.

  2. #2
    Project Engineer
    Join Date
    May 2015
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    127
    Not enough information. In addition to the spring constant, you'll need the length at closure to calculate the spring force on the valve. The valve opens at near zero flow. It is the pressure on the valve that begins it's movement away from the seat. Calculate the area exposed to the differential pressure and calculate the resulting force then compare to the spring force the spring force.

  3. #3
    Associate Engineer
    Join Date
    Mar 2018
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    2
    Thank you for your reply. The force on the springdue to displacement and preload is known and I calculated the equivalentpressure on the plunger based on spring force. The pressure acting on theplunger is the air pressure due to the differential pressure. But what air flowthrough the valve (switching flow rate) can generate this pressure (in terms orSCFM)? This switching flow rate would be unique to the valve and depended ofspring and I assume on the diameter (areas) of the in/out ports. Knowing the “switchflow rate” of the valve I can select the right number of them to connect to a pumpof know flow rate.

  4. #4
    Banned
    Join Date
    Jun 2018
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    A flow switch is a mechanical instrument that is utilized to control the stream of air, steam or fluid. flow switches work by sending trip signs to another gadget (a pump for instance) inside the framework, instructing it to close off or to turn on, which will additionally shield it from harm and for cooling circuit assurance.
    Flow switch decides whether the flow is above or underneath a specific rate, known as a set point. The setpoint can either be movable or settled, contingent upon the determination of the individual instrument. At the point when the setpoint is achieved, the reaction is frequently the invitation of an electric circuit. Once stumbled, the flow switch remains in its new state until the point when the fall falls beneath the set point. There are different types of check valves and with little bit different role of each.

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