Check Valves: Controlling Flow Direction
Hayward's check valves are available in PVC, CPVC, GFPP and PVDF materials. There are six distinct product families of check valve styles to choose from depending upon your application requirements.
There are four types of check valves:
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Ball check valves are used for non-viscous and clean fluids where there will be some system backpressure (≥2 PSI) to ensure proper operation.
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Y check valves are used for dirtier fluids and fluids having higher viscosities.
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Full body style swing check valves are used for larger piping systems and support maximum flow rate through pipelines; they can also be fitted with limit switches for position indication..
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Wafer check valves are also used for larger piping systems and high flow rates, especially when there are space restrictions or when the liquid contains solids which might foul a full body style swing check valve.
Some check valves are available with a spring assist, for applications that have low backpressure, dirtier fluids and for applications that benefit from quicker closing. Refer to models SLC, WCV and WC which offer this optional feature.
Hayward's design advantage is an all non-alloy construction; for the models that use a spring, the material of construction would be either 316SS or Hastelloy.
Hayward's TC model ball check valves have a true-union body design to simplify installation and maintenance. Reliable operation occurs without any needs for adjustments or settings. The line pressure moves the solid plastic ball off of the EPDM or FKM seat. When flow stops, the system back pressure pushes the ball against the seat stopping the flow. The ball is free floating, so it never seats twice in the same position, preventing uneven wear. Key features compared to other designs include that the ball is retained with the true union nuts removed and the ball is safety blocked.
Hayward's Y check valves are available with or without springs and their bodies with either standard or true-union designs. An advantage of Y check valves are that they can be installed in any position and work well with dirtier fluids. The Y design enables servicing in-line and the spring loaded models can be set to open within 2 ≥ 15 PSI. A common application for Y check valves are preventing loss of process fluid through spray nozzles once the pump is turned off. Another common application is as an anti-siphon valve when the process line is below the fill level of the feed tank of a pump system.
Hayward's
swing check valves have a truly unique and innovative design: each
half of its body is identical. Therefore, if one seat wears or
becomes damaged, you can reposition the valve in your pipeline after
adjusting the clapper and it's like having a whole new valve!
Swing check valves are often used for slurries or liquids that would
otherwise damage valve seats. Another great feature of the SW
series swing check valve is the built-in o-ring flange seal,
eliminating the need for separate flange gaskets. Hayward's
swing check valves can operate at nearly twice the pressure and
temperature rating of competitors valves and only require ≥3 PSI
for positive sealing.
Hayward's
wafer check valves are available with or without a spring. The
WCV series is available in 2" to 8" sizes and are a full pattern
design, requiring no spacers or special flange for full flow rate
and designed for both ANSI 125/150 and DIN/PN10 flanged pipelines.
The WC series requires a spacer for unrestricted flow and spacers
are provided with the valves through the 8" sizes; spacers for sizes
up to 24" are available for an additional cost. The big
advantage for wafer check valves is their compact size and high flow
coefficient value (minimal pressure drop). These are low cost
check valves for high flow rates that are lightweight and easy to
maintain. Spring assisted wafer check valves are typically
used for pulsating flow applications and horizontal piping where
quicker closure is desired to minimize backflow or water hammer.
Check Valve Installation Considerations
When installed downstream of a pump, install at a distance of at least 10 pipe diameters from the pump outlet and at least 5 pipe diameters from the nearest elbow or tee.
Additional Resources
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Download Hayward’s complete Engineering Product Guide for additional selection criteria, such as flow coefficient values, water hammer calculations and other technical formulas.
Additional Resources (PDF files)
Connections
Threaded connections are NPT (American
Standard) tapered pipe threads and it is suggested that a
non-petroleum based sealant such as PTFE (Teflon™) plumbers tape is
applied to your inlet/outlet pipe connections.
Flanged connections conform to ANSI 150# dimensions and a 1/8” thick full face gasket having a durometer rating between 50 and 70 is required for proper sealing for models that do not have a integral flange o-ring.
If you are not sure which check valve is most appropriate for your application, send us an inquiry, we typically reply quickly, certainly within 24 hours.