Scuba SCBA tank options for refills
Which setup would yield the most usable air for filling a Condor tank?
Single 88Cu.ft. 4500psi SCBA tank
or
Dual 80Cu.ft. 3400 psi. Scuba tanks cascade filling
Seems either way I’d spend about the same amount of money and portability is not a big concern.
Sorry if this has been discussed before.
*edited for clarification*
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Viewing 14 replies - 1 through 14 (of 14 total)
Savage, I get the point you are trying to get across, this is exactly how I was thinking and didn’t know which setup would yield more fills. But, your first tank is only going to fill your gun from 2000 to 2600 15 times, after which point your second tank is going to quickly chip away at that 68 fills number. An 88′ 4500 tank will go from 2000-2700 43 times by itself.
I’ve been emailing Joe Brancato, and he said that cascading will improve efficiency meaning you will get more gun fills out of say two 40′ tanks than 1 80′, but there isn’t an easy way to figure out if it will yield more fills over the SCBA without testing. Either way from running a bunch of scenarios through Airhog it looks like the two SCUBA setup will match the fills of one SCBA tank at best. With the cost of the dual SCUBA tank setup and filling 2 tanks vs. 1, portability issues, and just the extra step of transferring tanks when filling I’m just going to buy an 88′ SCBA tank like everyone else LoL. It seems that the 4500psi advantage is much greater than I realized at first.
M.H. I am probably wrong lol. But I think your right on the cascade set up. Lets say you fill to 2700 and refill at 2000. If you had two 3K tanks (like me and my friend) You fill off one tank (primary tank) then top off from the other tank only after the first tank stops at 2600. From the secondary tank your only using very little air. Look here http://www.airhog.com/tank.htm in the first scenario you are filling the tank from 2000 to 2700 and it gives you 10 fills from a 3K tank, in the second scenario you are topping off from 2600 to 2700 and it gives you 68 fills. With a cascade setup you may even get more because I don’t think you’d lose the pressure in between the lines of the two tanks everytime you disconnected. If you want max fills from ONE tank this is the one to get http://www.scuba.com/scuba-gear-200/043201/XS-Scuba-106-Cubic-Foot-Aluminum-Hoop-Wrap-Tank.html
Don’t you have some tanks of nitrogen at work for testing stuff you guys make? You could get the proper hose setup and fill your tank at work for free and only be out the cost of the hose. There was some info for this setup someplace, I will try to find it and let you know.
No, I do hydrotesting for safety reasons. For mig welding I use CO2. I could get a nitrogen tank from the company that does my C02 refills but I like to keep my hobbies separate from work, otherwise they become too much like work lol. Other than making a one-off piece or two here and there, anyway.
Standard nitrogen bottles are only rated 2015 PSI. If you got the 6000 PSI cylinder you’re set. Get some fittings from Brancato and you’re good to go.
Metal Head,
Don’t you have some tanks of nitrogen at work for testing stuff you guys make? You could get the proper hose setup and fill your tank at work for free and only be out the cost of the hose. There was some info for this setup someplace, I will try to find it and let you know.
Found two:
http://talonairgun.com/forum/viewtopic.php?t=2331
http://talonairgun.com/forum/viewtopic.php?t=4552
That’s what I thought about the volume. Then I read how by cascading you can get more “useable” air out of each of your tanks and I didn’t know if I was missing part of the equation.
Volume is Volume, it’s linear.
An example of a cascade fill station has one 4500psi tank filling two 4000psi tanks filling four 3500psi tanks and so on. Only the 4500psi tank gets filled from the compressor then is “cascades” down to the lower pressure tanks.
I was under the impression that by cascading you would increase the efficiency of fills. I’ve seen several references that two 44′ SCBA tanks are better than one 88′. I guess cascading SCUBA is not enough to overcome the pressure advantage of the SCBA though.
Two 80 cf tanks(160 cf total) filled to 3400 psi will fill a 490cc tank from 2200psi to 3000psi 15 times.
The 88 cf tank filled to 4500 psi will provide 31 refills at the same pressures
The CF tank is smaller and lighter but has a 15 year life, then it trash.
SCUBA tanks will last till condemned by inspection.
I’m pretty sure cascading two scuba tanks will just give double the volume, but you’re going to hit your fill pressure sooner. Thus it’ll be about the same number of fills. The single SCBA is the way to go. No one would be doing it if it weren’t.
I picked up my 1 hr. tank on ebay for about $200. Fittings are another $200+.
Just add the total fills from the two scuba and subtract that from the carbon fiber tank fills. 😆
You’ll want to make sure there is a place in your area to charge to 4500 PSI.
Here’s a fill calc.
http://www.airhog.com/tank.htm
I’m not sure if I worded my original post clearly. I wasn’t meaning option 1 and option 2, I was referring to a single 88′ 4500 tank vs. dual 80′ 3400 Scuba tanks cascaded. Will I really get more fills with the single 4500 tank? It got me thinking when I saw the Airhog tank is nearly $700 that I could buy 2-3 Scuba tanks and didn’t know which route would net more fills.
I’ve seen the Airhog calculator but don’t know exactly how to relate that to cascade filling procedures.
Anthony from TT lives nearby and referred me to a place to get the 4500 fills for $5!
Thanks for your help.
The 88 CF carbon fiber tank will give you about twice the fills and is lighter too. If your on the wall now, may as well get the big one or you’ll be buying again later.
You’ll want to make sure there is a place in your area to charge to 4500 PSI.
Here’s a fill calc.
http://www.airhog.com/tank.htm
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I agree with you. Have a look at that tank I put a link to. Lots of fills from that bad boy. I think it’s what Tony uses.