We have a building with a double check backflow assembly on the suction side of a fire pump. Normally there is a minimum of 10 pipe diameters of vertical plane pipe just before the suction flange.
Is the double check backflow allowed within that distance?
Are there requirements for the backflow to have flanges vs. grooved connections?
A colleague said the control valve should be OS&Y rather than butterfly on the suction side only. Why would this be the case? I would assume the OS&Y would reduce turbulence better than a butterfly, but wouldn't the checks also cause turbulence?
Thanks in advance.
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