smc valves... got a question

so i finally mounted my valves on my frame and i was testing them by airing them up with a nitrogen bottle i had @ 120 psi. They would open and fill fine but once i disconnected the bottle and let the pressure out of the inlet line with the ball valve they wouldnt hold pressure in the bag and they leaked out of the fill.

My questions are... 1.) do they require pressure on the inlet side at all times?2.)is there a way to fix it w/o a check valve

there all wired and plumbed correctly so that is not the issue, they just start dumping as pressure on the inlet side is dropped(before the valve)

Yes they require back pressure to stay closed. A check valve is probably the only fix.

what he said, i used to run nitrogen and smc valves and when id park it and close the tank without dumpin my truck it would come down in a couple of hours

not to steal your thread bro, but im buying some SMC valves from a guy on here, am i going to need to run a check valve? and what does a check valve do?

yup they need backpressure to stay closed.

If you put a check valve right between the air supply line and the up valve, it will keep air in your bags if your lose pressure in your tank or if you remove the nitrogen tank.

Another thing I noticed was before I got check valves with my SMCs was if I hit a bump hard it would dump all the air out of my cylinders back thru the fill valve and into the tank. I like my valves alot more after the check valves were added.

a check valve only lets air pass through in one direction so it creates the back pressure you need to keep them inflated

yeah what they said....either keep enough air in ur tank or get check valves

There are valves on the market that dont require check valves but check valves are the quickest way to solve your problem. We have ones at the shop that go directly in your valve.

my brothers SMC's stay aired up for weeks and he dont have check valves..?