Hydro-Flo Foam System

The Hydro-flo system is one of many examples of how Grindley excels at both producing, assembling and testing assembled components.

The Hydro-flo system is a foam delivery system that delivers the same amount of firefighting foam over a wide range of water pressures.   This system requires fairly complex valving and closely held tolerances to accomplish its purpose.  Because of our wide range of machines it made the producing and matching of close tolerance fits possible.

    The Hydro-Flo can be split into two major sub-assemblies, 1)Drive and Pump, 2)Operating and regulating valves.  The Drive and Pump consists of two opposed cylinder piston assemblies with a shaft connecting the two.  Water will be in one of the cylinders and foam will be in the other.  As the water is forced in on the drive side it forces foam out the pump side.

    To make these cylinders we took advantage of the turning and milling capability of our Mill-Turn machines.  Using these machines we were able to hold our turned and milled dimensions consistent to each other, assuring that alignment in assembly would be acceptable.   If the 4 holes that tie the assembly together are out of alignment with the bore then when assembled the two cylinders would be skewed to each other and would bind when tightened.  The shaft that connects the two cylinders and holds both pistons, is also a part that we were able to get the benefits of Mill-Turn.   Although this is a simple shaft, the fact that we were able to mill the wrench flat at the same time that we faced and drilled the part makes us that more efficient.

    There are two valves that make the drive-pump assembly work.  We call it the operating valve for obvious reasons.   The body of these valves are made on our CNC mills.  The benefit of the hydro is that it keeps a constant flow of foam because it reciprocates, pumping foam out on one side of the piston while pulling in foam on the other side.  There are two valves involved with the operation of the hydro-flo.  The first is the pilot valve and the second is the operating valve.  On the shaft there are mounted two rings.  When the shaft is driven one way these rings trip the pilot valve.  The spool in the pilot valve redirects the the flow of water to the operating valve.  The operating valve redirects the flow of water to the other side of the drive piston, thereby creating the reciprocating action.