For the most comprehensive procedure in sizing Series 118/108SA control valves, it is best to use our ValveMaster software or the guidelines shown here in conjunction with the Performance Charts in the Engineering Section of the OCV catalog.

The flow required through a surge anticipation valve can be difficult to determine, so a general guideline is to use 60% of the rated pump flow. The 118/108SA Series valve is capable of intermittent flows up to 45 ft. per second. Surge Anticipation Valve sizes are typically 50-60% of the mainline size.

where:

        Qmax = maximum flow rate, gallons per minute
        DP = pressure drop, psi*
        sg = liquid specific gravity (water = 1.00)

* For valves which exhaust to atmosphere, the DP will be numerically equal to the low pressure setting.

From the chart below, pick the smallest valve that has at least the Cv determined above, and where the velocity does not exceed 45 ft/sec.

Flow chart for full port valve.