Slider air tanks

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staggrlee

staggrlee

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Finally got around to plumbing my compressor into the sliders. Thanks Rohitash for the inspiration and excellent write-up! I should now have all the flotation I need for those deeper river crossings :hhmm:

I estimated the volume of the 2 sliders to be around 5 gal. and I'm currently running them at 150 psi. I tried to tuck the fittings up as close to the body as possible and I went with the more inexpensive 1/4" plastic airline. If a line should get snagged the line will break before the fittings.

Takes about 90s or so to fill the tanks using the AMK compressor I picked up on CL. The compressor draws about 40+ amps as it approaches full pressure but doesn't get hot enough for me to be concerned about the location.

I filled them to 150 psi last night and shut off the compressor. They were still at 120 this morning. I think that's about as good as I can hope for since I think any OBA is going to have some leak down. Anyway here's a couple of shots of the sliders and the compressor/gauge previously installed ...
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Nice job!
I've been playing around with the idea of doing that myself, or putting tanks up between the frame rails and the body, outboard, just above the sliders.
 
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Did you drill holes at one point of the square tubing before welding up the outer rub rail so that you could use the tube for extra capacity?

5 gallons seems like a lot from a pair of rock rails.

Also, while i know you are joking, filling the rock rails with compressed air will actually make them weigh more than if they were at standard atmospheric pressure. Filling them with air doesn't increase the volume of the container, like it would with say with a baloon. So, the rockrails displacement in water is still the same, therefore no more "extra" buoyancy. :)
 
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Even if it were 2 gallons on each side, it sti seems like a lot. Do u think there is air in the round rails as well or do u think it's just the square tubing?
 
3D FJ said:
Even if it were 2 gallons on each side, it sti seems like a lot. Do u think there is air in the round rails as well or do u think it's just the square tubing?
Click to expand...

He would have to have drilled a hole into the side of the square tubing before welding the round tube to get air to that portion.
 
Layonnn said:
He would have to have drilled a hole into the side of the square tubing before welding the round tube to get air to that portion.
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I can't read anything on my iphone. You already said that ^^^ before didn't you. :)
 
No, you guys are right. Thanks. I assumed that the tubing and box sections were connected, but then why would they be? :whoops: I don't think I'll go knocking holes in the sliders and plugging them back up.

Based on the box portions alone 2(3*2*72) = 864 cubic inches which is ~3.5 gallons. It's actually 3.2 US dry gallons and 3.7 US wet gallons. I'm not sure which is the std. measurement for compressed air.

The tubing (forgetting the stubs) would add 3.14*1^2*72 = .98 gal

And 90s was an overly optimistic estimate too. It's actually 3.5 minutes when I'm paying attention and timing the fill.
 
I calc'd only about 1-gallon per main 2x3 for my slider rails...but I'm using quarter wall.
 
staggrlee said:
I filled them to 150 psi last night and shut off the compressor. They were still at 120 this morning. I think that's about as good as I can hope for since I think any OBA is going to have some leak down. Anyway here's a couple of shots of the sliders and the compressor/gauge previously installed ...
Click to expand...

That sounds like too much of a drop in pressure in too short of time. If you have a pool/pond or soapy water, I'd drop those sliders into it and see exactly where you're losing air at. It's worthless to have air tanks if they're empty when you need them, and it's hard on the compressor to be constantly going on to keep the tanks presserized if you have an auto regulator switch. Something to think about... :hhmm:

I'd expect a ~5psi drop over several weeks or so.
 
staggrlee said:
No, you guys are right. Thanks. I assumed that the tubing and box sections were connected, but then why would they be? :whoops: I don't think I'll go knocking holes in the sliders and plugging them back up.

Based on the box portions alone 2(3*2*72) = 864 cubic inches which is ~3.5 gallons. It's actually 3.2 US dry gallons and 3.7 US wet gallons. I'm not sure which is the std. measurement for compressed air.

The tubing (forgetting the stubs) would add 3.14*1^2*72 = .98 gal

And 90s was an overly optimistic estimate too. It's actually 3.5 minutes when I'm paying attention and timing the fill.
Click to expand...

Keep in mind a 2"x3" section of boxed tube is the measurement of the outside, not the inner dimensions.
 
r2m said:
That sounds like too much of a drop in pressure in too short of time...
Click to expand...

Thanks, good to know. I've checked for leaks all along the way. None on the sliders, manifold or outlets.

We're on our way from Seattle to Newfoundland today. I'll drive it out into the Atlantic while we're there. :p

Seriously though I'm inclined to suspect the push-to-connect airline fittings that I chose for field repair-ability. Either braided hose/threaded fittings or flare fittings would probably be more airtight. Even if it only kicks on to top up every 8-10 hours or so, I can live with that. For now.
 
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staggrlee said:
Thanks, good to know. I've checked for leaks all along the way. None on the sliders, manifold or outlets.

We're on our way from Seattle to Newfoundland today. I'll drive it out into the Atlantic while we're there. :p

Seriously though I'm inclined to suspect the push-to-connect airline fittings that I chose for field repair-ability. Either braided hose/threaded fittings or flare fittings would probably be more airtight. Even if it only kicks on to top up every 8-10 hours or so, I can live with that. For now.
Click to expand...

Roger that.
Hope you have a great trip and all works out!
 
Q: Did you build those sliders yourself/with a friend? Or are these an off-the-shelf item from a vendor and you just plugged and ported?

As noted above, I've been thinking about building my own sliders. Is there any reason one couldn't use a 2" x 4" or even a 2" x 6" rectangle material for the slider and just have it tuck further under the body, and still have the tube step?
Industrial Metal Supply has a wide range of material to choose from: Steel - Industrial Metal Supply Steel Products and Steel Shapes

Just a thought about a direction I'm going to look into.
 
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