Hydra-Shield's Pre-Con Valve is a suction inlet valve designed to operate as an automatic flow control valve. We have only encountered the use of the Pre-Con Valve a couple of times during our travels and it appeared to work just fine during drafting operations. The "free-floating" position of the valve seems to be the most appealing feature of the valve during drafting operations. In the free-floating position, the pump operator can switch between drafting and using onboard tank water without having to run around closing an intake valve.

The one piece of data that we do not have is any flow restriction under drafting conditions. Since this is an aftermarket, external suction inlet control valve we would expect there to be some reduction in maximum pump capacity when using a single suction inlet.

At our 2013 rural water supply seminar in Oconee County, South Carolina - we had a chance to see a Pre-Con Valve in action on a rear suction inlet of a pumper and it worked just fine.

Here is a link to the Pre-Con Operating Manual

http://www.hydra-shield.com/images/Manuals/pre-con%20manual.pdf