Check valves

If there are check valves in line shouldnt that prevent a leak to cause the air in the tank to leak down?

yeah unless you have a leak directly on the tank....

no, it depends on how you set it up, i think most would use 4 check valves in front of their 4 fill valves, so that if there's a leak in one bag, the other 3 will still hold pressure. I can't think of any way to set it up that you would seal the tank and still be able to fill your bags...

That way will work and I have it like this on my daily driver

I installed it wrong in front of the fill valves then it wouldnt dump, now it is in between the tank and fill valve.

infront of fill will work as long as its before the dump but this way is kinda pointless. I would mount the check valves directly on the tank so if an air line blows you done loose tank pressure because it is checked directly at the tank itself.

Thats what I did, my logic was flawed.

as long as theres no leaks elsewhere on the tank it should hold

in that set-up it's the fill valve holding the tanks pressure in. the check will only keep pressure from the bag filling an empty tank.

So my fill and dumps are run off a T.I should put them off the tank before the valves so if the tank looses pressure the bags wont correct?