Adding a tank to OBA system

[hardtopper]

For York compressors, I'm of the opinion that the tank serves a purpose, even if it's a small one. Yorks put out a lot of air, but it's a noticeable puff-puff with the piston stroke. In theory, the tank provides the reserve capacity to even out the "off" cycle and provide a steadier flow. I haven't done an A:B comparison, though, so take it with a grain of salt.

 

[Mr. Bills]

For York compressors, I'm of the opinion that the tank serves a purpose, even if it's a small one. Yorks put out a lot of air, but it's a noticeable puff-puff with the piston stroke. In theory, the tank provides the reserve capacity to even out the "off" cycle and provide a steadier flow. I haven't done an A:B comparison, though, so take it with a grain of salt.

Some friends and I once experimented with various size tanks and also no tank at all on a friend's CJ-7 with 360 AMC V-8 and York onboard air system. We tried a Hadley 1/2 gal. air tank which only measures 5" dia. x 7" long, also the longer Hadley 1 gal. tank that I was using at the time (supplied by Currie Enterprises as part of the 12v onboard air kit that it marketed in the mid 1990's). We also borrowed a 2 gal. tank from Brad Kilby.

After some testing we determined that the length of 3/8" rubber air hose from a junction block near the compressor to an air chuck at the rear of the jeep was enough of a "buffer" to eliminate unnecessary cycling of the compressor. Pulsing of the air flow at the air chuck was minimal with no tank and totally eliminated with the 1/2 gallon tank.

Our conclusion at the end of the experiment was that a 2 gallon tank provided no benefit over a 1/2 gallon tank and that a tank really wasn't necessary at all.

YMMV

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P.S. - I still have the 1/2 gal. Hadley tank that we used - sitting in a parts box. The 1 gal. Hadley tank is still in use on the CJ-7 that I sold to my younger sister in 2011.

 

[hardtopper]

Good data points, Mr. Bills. I'm not surprised the 1/2 ga tank was enough to eliminate it. However, I am a bit surprised that the length of hose was enough to almost get you to that point on its own. Although...doing some math on hose volume over that run would probably show that it was comparable to a small tank, and that gave you sufficient reserve capacity right there. I'm not sure whether or not a check valve at either end of the path would affect that.

 

[Mr. Bills]

Good data points, Mr. Bills. I'm not surprised the 1/2 ga tank was enough to eliminate it. However, I am a bit surprised that the length of hose was enough to almost get you to that point on its own. Although...doing some math on hose volume over that run would probably show that it was comparable to a small tank, and that gave you sufficient reserve capacity right there. I'm not sure whether or not a check valve at either end of the path would affect that.

My recollection is that there was a check valve at the compressor. I always use one.

 

[mrblaine]

Adding a tank adds no complexity worth worrying about. I added a 2.5 gallon tank to my York OBA system and it was problem-free. It ran air tools effortlessly.

To clarify for those that may not fully get it yet, the tank had exactly zero to do with the ability of the system to run air tools. The most basic test of that for anyone who wants to understand is to run the system until the compressor shuts off. Hook up your favorite air tool and count how many seconds it will run before the pressure switch turns the compressor back to compressing air. 3, 5, maybe 10 seconds? That is the reserve in the tank that will run an air tool. Or, if you want to learn it the hard way, fill the system and shut the engine off. Now hit the button on your favorite air tool. How long will it run at full speed? That length of time is exactly what the tank is adding and that is simply not going to work.

Further, the actual useable capacity in an air tank is the volume that it takes to go from your shut off to turn on pressures at the pressure switch. Most systems are set at around 85 psi cut on pressure with a 125 psi shut off limit. That is not much volume in a 1-3 gallon tank.

If you want to foolishly run air tools in today's world, the correct way to do it would be to run the tool until the compressor kicks on, stop, wait for the tank to refill, hit it again and keep repeating that until it finally sinks in that the tank does not do one thing for the ability to run air tools. Only the CFM output on the compressor determines that. If the compressor does not have enough of an output to run the tool, no tank that a sane person will put in or on a Jeep will change that or make the running of air tools any more effective.

 

[mrblaine]

As many have said, what do you do with the tank? How long can you use it before the compressor turns on and what do you use it for? Most of the time the compressor turns on within seconds and that's it, tank done. I have a tank and even so I think I've come over to the dark side, there just is no point.

If by dark you mean enlightened, then you would be correct. At some point, we can hope that knowledge will finally equal understanding.

 

[mrblaine]

I have a viair tank ,behind the backseat ,nice but takes up a decent amount of space is the only downside, but then my backseat pretty much does also.

Real estate in a TJ is valuable. You should use that space for something of value.

 

[mrblaine]

A ratchet strap around the tire and tankless OBA is more than up for the task. I've seated a bunch of tires this way. If the tire decides to be tricky you can set it on a bucket, tree stump, or rock so that gravity pulls the bead down along with the ratchet strap.

And we keep doing this. I've seated the beads on 100's of tires, not once have I used a ratchet strap to do so, it simply isn't needed. It is the air tank of the bead seating world. Gravity is all that is needed.

 

[jjvw]

The last bead we needed to reset, we jacked the tire off of the ground, wiped the dirt off the bead and seat, attached the air and gave the tire a shake. That was enough to create the seal. The rain might have helped a bit.

 

[Viking Jeeper]

I keep my spare at max psi. Just a good reserve sitting around to use

I've always wondered if anyone else did this.

 

[StG58]

Interesting. Every time I throw something out there, sit back, and listen...I learn something.

 

[jjvw]

I've always wondered if anyone else did this.

What do you use to transfer the air out of the tire?

 

[Viking Jeeper]

What do you use to transfer the air out of the tire?

A dual deflator/inflator system I made. It can deflate or inflate two tires at a time. Just hoses and air chucks with a valve. I figure it can inflate one tire from zero psi to half of the spare (minus loss). What could be the downside?

 

[mrblaine]

A dual deflator/inflator system I made. It can deflate or inflate two tires at a time. Just hoses and air chucks with a valve. I figure it can inflate one tire from zero psi to half of the spare (minus loss). What could be the downside?

I know an excellent resource for the answer to that. I sent him an email asking him to clarify.

 

[jjvw]

I know where this is going.

 

[mrblaine]

I know where this is going.

I don't, yet. I know that Harry used to tout that as a viable emergency compressed air solution but I also seem to recall some incident that moved him away from that. I could easily be remembering it incorrectly.

 

[jjvw]

I don't, yet. I know that Harry used to tout that as a viable emergency compressed air solution but I also seem to recall some incident that moved him away from that. I could easily be remembering it incorrectly.

Ah! I was thinking of someone else. I'm interested to know the rest of the story.

 

[mrblaine]

Ah! I was thinking of someone else. I'm interested to know the rest of the story.

I recall something about 70 to 80 psi in a normal load range C and D as a reserve. I know they can do it, just not for how long. All that stunt driving you see with the skids and sliding is done on highly inflated tires.

 

[Mr. Bills]

I remember Harry's "air robber" from his Ecological 4-Wheeling newsletter, although I'm sure it was called something else.

I thought of him recently when I switched over to a 255/85R16 spare and filled it to the maximum pressure on the sidewall rather than the street pressure for my jeep.

I can connect an air chuck to each end of the Flexzilla hose that I use with my onboard air and equalize the pressure between the spare and another tire should my compressor fail and I have to McGuyver myself to pavement. Frankly, I doubt I would ever need to, but its nice to know I can. I didn't consider 80 psi, just the 65 psi on the sidewall.

 

[Mark K]

I thought I had an air stealer. Might be in the storage locker Alladin's Cave, dunno. So, I researched on the Big A and turned up the following:

Pair of closed flow locking air chucks:
https://www.amazon.com/gp/product/B01BUETYNI/?tag=wranglerorg-20

10 foot coil hose with male pipe threads both ends:
https://www.amazon.com/gp/product/B07F1T4HJJ/?tag=wranglerorg-20

Total just under $18. Some will prefer a straight hose.