Big Blue's Transformation

[Gary Lewis]

Jim - It turns out my portable tank is this 11 gallon one from TSC.  And it works really, really well.  So I'd be happy to buy another if it'll fit.

Bob - You have a good point, you do have to fill the tank and the tires.  So, as you say, the benefit of pumping against lower pressure gets negated by having to fill the larger volume, and at some point it is a wash.  But we don't know what that point is.

As for what I did to Big Blue today, I got the winch, aux battery, and interconnecting cable off.  (And I got the winch installed on the trailer for next week's trip.)

And, I did a test of an air tank.  I took the 11 gallon one to 118 psi on its gauge, which was as high as my shop air system wanted to take it.  And I dropped one of Big Blue's LT285/75R16's to 15 psi and aired it back to 30 psi.  That took 30 seconds and dropped the gauge to 78 psi.  Then I dropped the tire back to 15 psi took it back up, this time overshooting to 32 psi.  That dropped the tank to 45 psi and took 60 seconds.

But, I can't get that particular tank in.  In fact, it looks like the max height is 8" to keep it concealed as that would put it even with the bottom of the fender.  And max width is 16", but most tanks are round so that distance may be irrelevant.  If the tank is no more than 8" in diameter the length can be up to 37" long.  But if it is 16" wide then it can only be 27" long.

LOL!  I saw that Jim posted almost the same dimensions.    

[ArdWrknTrk]

Yeah, I was looking at the link before finishing your post and thinking. "29-3/4 in. x 21 in. x 13-1/2 in"  ... That is going to hang down.

But you're right.
You can go forward (up under the cab) and gain a lot of length.
If you keep diameter down.

Or maybe you go with something a bit deeper (10"?) and take the risk.

Do you really expect to high center in a truck as high as Big Blue?

[ArdWrknTrk]

Are we looking for something in the 10-15 gallon range now?

(why can't this damn country get with metric?) 😡

[ArdWrknTrk]

This looks like a good possibility given that the handle, wheels, etc make it seem bigger than the tank itself.

I'd go measure one in store but HF is 20mi away and it's rush hour here.

[ArdWrknTrk]

Maybe two 8" x 36" tanks??? (Would fit 8x16x36 envelope)

I'd have to figure the volume, but you lose a lot with diameter...

[Gary Lewis]

Actually, that 37" was going back, back to the rubber wheel well flap.  The 8" diameter would allow it to go above the step bar and outboard of the spring mount.

Yes, I'd like to have something around the 11 gallon range as that gets two of the tires up to 30 from 15.  And toward that end I've done some calculating.  (And I see that you've replied twice while I've been working on this response.  So let me get this out and I'll try to respond to your latest posts.)

I measured the existing tank and calculated the volume and came to 10.3 gallons.  So, I'm fairly confident in my calculations, but just not my measurements.  Anyway, using those calculations an 8" x 37" tank would have 8.1 gallons of capacity.  So, we are on the right track.

[ArdWrknTrk]

Two 8x36 would be 15.666 gallons (nominal)

You could stagger one back past the spring hanger and one (on the rail) forward under the cab.

But check that HF compressor, it might fit!

[Gary Lewis]

Ok, that HF tank is supposedly 10 gallons and the overall unit is 30" long.  So the tank itself may be 24" long.  But it sure looks longer than that 'cause my air tank is 21" long and 12" in diameter.  So I'm guessing that the 30" doesn't include the handle.

And, if it measures 8" in diameter I could put two of them side-by-side.  Or, I could just go with one of them as it would do two tires from 120 psi.

However, my calc's say that a 30" long tank of 10" in diameter would be have 10.2 gallons of capacity.

[ArdWrknTrk]

I'm thinking their "dimensions" are the size of the box it's shipped in.
And the handle isn't attached in the box.

I may be wrong, and I said I'd check the actual item before committing.
But it would get you all the accoutrements!

[Gary Lewis]

I will check it out, but can't do so for a few days as I'm not going to get down into Tulsa where the HF store is.

And, I sure appreciate you taking the measurements as well as looking for a compressor.  Thanks!

But, one thing I've not checked out is the space below the tool box and across the front of the bed.  I'd rather not use that as it might be good storage for something.  And, I'm pretty sure it is very narrow.  But, it is also probably twice as wide as what we've been talking in length, so.....

[ArdWrknTrk]

That would make it impossible to close the gate on a 4x8 sheet, but you're not in the construction trades, so...

I have seen some 48" tanks. (those would fit between the wheel wells)
I think I'd have close to 60" if I didn't have a drop-in bedliner.

IF I get to HF for the 'sale' (always a sale) ill check it out and post back.

[Gary Lewis]

With that monster spare in the middle of the bed it is hard to get a sheet of anything in.  I still need to get that bumper built.  

But placing the tank under the toolbox would prevent closing the 'gate with a sheet in there.

[grumpin]

Do you need something at Harbor Freight measured? I’m 5 minutes from the one here.

[FoxFord33]

Would a disused CO2 bottle work? That may be more expensive unless you already have it lying about...

[ArdWrknTrk]

SCUBA tanks are aluminum and rated MUCH higher than your usual 125psi compressor.

What do they do with the ones that fail recert?
Not fail catastrophically, but fail the stretch test?

You know. When they place them in a tank and see if the displacement changes under pressure.

[Gary Lewis]

Yes!  PLEASE!  Their 10 Gal. 2.5 HP 125 PSI Oil Lube Air Compressor.  And the real question is what the dimensions of the tank are.

Ideally I'm looking for a tank that is 8" in diameter and no more than 37" long.  But we aren't likely to find one that is a perfect fit.  So, if you could measure tanks on their compressors that are sort of close it might be a big help.  THANK YOU!

And speaking of a perfect fit, there's a chance that I could get the guy that is supposed to build my rear bumper/spare tire carrier to make the tank to fit.  He'd already said he could make the rear bumper into an air tank, but after discussing it here and making many holes in the bumper itself during the design I decided to not use the bumper that way.  However, a piece of tubing with the ends welded up, fittings welded on, and brackets added might be easy for them to make.

So, two 8" pieces of tubing, one 37" long and one 27" long, would yield 8 and 6 gallons respectively.  Hmmmm......  

[ArdWrknTrk]

What about a scuba tank????

At standard pressure (3,000psi) they are 80 cu' (or @30 psi, 100 times their volume)
It would be the same as 600 gallons volume at atmospheric pressure. *14.7 @ sea level.
So, about 150 gallons @ 29.4 psi. (or 300 to raise tires from 15-->30)

You would definitely need a regulator, but you wouldn't have to worry about oil or condensation., and the fill would be FAST.

[Gary Lewis]

Steve - A CO2 bottle?  How big are they?  How heavy?

Jim - A SCUBA tank, with oxygen?  That is interesting.  It looks like the tanks go for ~$100 used to maybe $250 new.  But where do you get them filled?  I didn't find anything in Tulsa.

And, what kind of a regulator?  That would be a serious step-down in pressure.

[ArdWrknTrk]

Oh no, you don't want oxygen!

Regular air (about 78% nitrogen, 20% oxygen, argon and other trace gases fill out to 100)

You can get a certed tank filled at any dive shop.
You'll need an adapter for scuba, but then you can use a normal regulator for nitrogen, argon, whatever....

[ArdWrknTrk]

I just checked and an 80 fill at Cap'n Mike's dive shop is $5
(cheaper if you join the customer rewards thing where you get you card punched for a freebie)

At any rate, definitely faster to fill than a compressor and enough to seat a bead if it ever came to that.