Bill, Your 3HP system might have enough suck so that you won't care about a leaky blast gate. I loosen them (thumb screw), move the gate, and tighten. You can set them sort of tight and just move the gate but I find the gate will not seal 100% and then vibrates. Personally I wouldn't worry about it, just install it, play with it, and you'll make it work for you. A little caulk on the gate might provide enough pressure for your likeing. Of course you can always install the fancy automatic blast gates