Hey Guys______ The situation is this: I have a 12 volt compressor (Quick Air II), with a 7 gallon tank (manual says 5 should be max.), and a pressure valve that cut everything off at 115psi”s… So, the question is ____ after the initial full up of tank, the comp. shuts off, I start the airing up process and immediately after starting airing up the compressor goes on. What’s the purpose of the tank, if it’s playing catch up? Air is going from compressor to tank than to tires, correct, if so, what purpose does the tank serve in the airing up process, the reserve capacity is only used initially when stating off(for a second or two), and then, compressor still starts immediately. Then I continue to air up until all four tires are full. If the tank is playing catch-up, why have it? Why not run straight off the compressor??? I’m talking strictly air up, not tools. Also does the size of tank matter if I have let’s say a 2 ½ gallon capacity would that make the system more efficient??? ______ THANKS BAYRUNNER

 

Sounds perfectly normal, while your compressor shuts off at 115, it likely turns on at 100 psi or so. As soon as the pressure in the tank drops below 100, the compressor kits in. For a demonstration of the benefit of the tank, try airing up from a dead start and then again with the tank aired up. I find on my setup, I save 1 minute with the tank full (6 minutes/4 tires vs. 7 minutes). Also, while you are moving from tire to tire, that compressor is still filling the tank. So, with the QA-II pumping about 2 CFM, if it takes you 30 seconds to move from one tire to the next, the compresor has pumped 1 cubic foot of air into the tank and as soon as you hook up the chuck to the next tire, that air flows quickly into the tire. Also, the tank is handy if you need to reseat a bead, there you need volume.

I have some information on tanks and air requiements on my OBA page: http://www.4crawler.com/4x4/CheapTri...tml#HowMuchAir

I currently run about 2 gallons (front bumper tubes), hope to the up that to 4.5 gallons with a second tank. As I write on the page, you can never have too much air storage.

 

________ Thanks for the feedback 4Crawler _____ BAYRUNNER

 

This is exactly the reason I lug my tank around.