Air & tank ?

I just gone done doing a air suspension on a 78 Elco. I aired the elco up and had to do some work on the tank and let all the air out of the tank and the elco layed out. I'm under the impression that if you have air in the bags and let out the air from the tank that the car will stay up? any info on this will be greatful.

Thx PachecoKustomz

its got to do with the valves not having enough pressure to keep the diaphrams closed and check valves will keep that from happening.

heres a previous post i found from doing a google search from iLLblazer who could explain it better than myself -
"People run them because if you ever lose tank pressure, your fill valves will open up and the air from your bags will drain out through the fill valves. I dont think it happens with ALL valves, but some need backpressure (ie tank pressure) to stay closed"

My first thought was check valves too. Need 1 at each corner. Torn air-line or loss of pressure in tank (etc,etc) will cause baggs to deflate.

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LowLyfe83 said:

its got to do with the valves not having enough pressure to keep the diaphrams closed and check valves will keep that from happening.

heres a previous post i found from doing a google search from iLLblazer who could explain it better than myself - "People run them because if you ever lose tank pressure, your fill valves will open up and the air from your bags will drain out through the fill valves. I dont think it happens with ALL valves, but some need backpressure (ie tank pressure) to stay closed"

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What he said. Most valves are designed to contain pressure on only one side. Thats why they are marked to show direction of flow. Your (up) valves are set up to keep the tank pressure away from the bags until you open them up, and your (down) valves are to keep pressure in the bags away from the outside atmosphere. If the pressure drops in the tank, your (up) valves will allow air to trickle back into the tank until the pressure on both sides is equal. Hope this helps!

valves are directional. hence the reason they all have arrows on them. so if you install one backwards your compressor will air your bag up as well. they will only hold pressure 1 way. you will need check valves in line of your fill valves to keep the car up if you ever rupture a line or something.

I use Norgren valves and do not have this problem. I can drain my tanks and the truck will stay up without a problem. Doesn't really help the OP but its good info that all valves are not the same.

yea the best way to stop the problem is a check valve inline between your tank and fill valve, this keeps back pressure on your fill valve and prevents it from leaking back.

I want to thank all of you for this info.. I'v done hydo's on Impala's, trucks, and truck beds so I thought it would have the same concept.. my bad!!