Scuba tank fill?

[T-Man]

How many times can you fill a PCP gun (Fortitude with 135 cc cylinder) with a standard 80-100 cu ft scuba tank?

[T3PRanch]

https://www.gatewaytoairguns.org/GTA/index.php?topic=140859.0

[Doug Wall]

Since the scuba tank is 3Kpsi, and the Fortitude is a 3K fill gun, you will get one full fill. After that you will get partial fills. The fill calculators will give you better info. Don't forget that you lose some air from system pressure bleeding every time you fill the gun.

[T-Man]

Since the scuba tank is 3Kpsi, and the Fortitude is a 3K fill gun, you will get one full fill. After that you will get partial fills. The fill calculators will give you better info. Don't forget that you lose some air from system pressure bleeding every time you fill the gun.

Well it seems like a scuba tank is pretty much useless then, isn't it?
Thanks.

[Ribbonstone]

Yep...been out dated.  HAd a pretty good use for rifles that had a 2K fill....with a friendly dive shop near by, was a useful option for a Disco/Maxi/Challenger PCP.

In your case, so long as the air fill is higher than whatever the Fortitude regulator is set for, it would shoot just as well/fast....just not for as many shots.

[CableStop]

Filling a 135cc tube from 1500-3000 PSI with an 80 cubic foot tank should drop the tank pressure about 20 PSI each time, so you could get a couple fills out of it before it started to get noticeably low.  I mean it's definitely not ideal but not useless if you just want something to take with you when going to the range it would work well enough.  I think a 4500 PSI SCBA tank is definitely a better choice but they're a lot pricier.

[T-Man]

I'll just hand pump the bastidge.

[HunterWhite]

Do you already have a scuba tank?

Hunter

[Farrier1]

I'll just hand pump the bastidge.

That's what I'm doing. I only use my airguns near the house anyways. Little hard to crack off powder burners with my horses and cattle dogs not too far from the home. I just got a Marauder but I have a Hatsan AT44. I might have to hand pump it once every 2 weeks. I'm plinking ground squirrels and woodpeckers.

[Mike -]

Most folks AND manufacturers agree (if you read the manuals) and recommend NOT...FILLING an air cylinder.
It's easier on the parts and pieces of you don't go that last few psi.  Mainly the o-rings will last longer, possibly the sear, hammer spring from not having the extra load put upon them.

I normally stay down at 200 bar for a 250 bar fill and 200 to 250 for a 300 bar fill.
So what if I don't get that last few shots off without having to fill the cylinder again.

Mike

[T-Man]

Do you already have a scuba tank?

Hunter

No.

[JimD]

Used SCBA tanks are not necessarily very expensive.  I bought a Yong Heng and an expired SCBA tanks with the fill set for about $600.  Not everybody wants to use an expired tanks but I think it's OK.  You can also find tanks that aren't quite expired yet so you don't have to get a compressor right away.

[CableStop]

Used SCBA tanks are not necessarily very expensive.  I bought a Yong Heng and an expired SCBA tanks with the fill set for about $600.  Not everybody wants to use an expired tanks but I think it's OK.  You can also find tanks that aren't quite expired yet so you don't have to get a compressor right away.

Oh yeah if you go expired it's cheap, I just bought two expired 66 cu tanks for $160 shipped on ebay.  I just figured most people getting their tank filled at a shop don't want to have to buy a compressor big enough to fill a larger tank.

[HunterWhite]

I had scuba equipment from twenty years ago.  I still had regulators, masks, tanks, buoyancy compensators, flippers, wet suits, etc.
SCUBA tanks are HEAVY! My 80 cubic foot scuba tank weighs close to 40 pounds when its full of air. Remember that underwater tanks must be about the same weight as water for it's size. My tank will sink when its full and float when it's nearly empty.
The large SCBA tanks weigh only about 12 pounds empty, I don't know the weight when full of air. These are much easier to move around than the underwater tanks.
The rifle that I shoot the most is regulated at 1500 PSI. This means that I can use either the SCBA or SCUBA until it's down below 2000 PSI.
If I leave the fill hose connected while bench shooting it seems to go forever. I do this when I'm testing different pellets at different speeds.

I live 20 minutes from a dive shop, and not much farther is a paint ball park. If I were just starting, I would just get a 3 liter (30 minute) tank.  The carbon fiber still costs a bit more but it's so much easier to handle.

Hunter

[T3PRanch]

I have 2 Steel SCBA 4500 PSI 80 cu/ft tanks I recently picked up from e-bay for $175 each shipped from India. They were like new and manufactured in 2019. They were from From salvaged Ships. They have the joy of never expiring like Carbon Fiber SCBA Tanks. There is no tank gauge. The Valve is DIN300. Drager Brand. They weigh about 20 lbs each.

[avator]

When I first got into the PCP game I had 3 of the FD-PCP guns... I filled them to just under 2k so I ran back and forth to a paintball joint (8miles away) that filled my 80cf and 100cf scuba tanks to 3300psi for $8 each. When it came time for vis and hydro testing I had to make a 90 mile round trip run.. (twice for a hydro test because it took a week). That got old and pretty much useless when I moved up to the 3k guns. The money I could have saved would have paid over and over what a compressor would have cost.
You don't need to buy a super whamadyne $3k compressor.
Just commit to filling guns directly from a $300 Chinese compressor or a $500 portable 12v/110v jobber.

[PG in San Diego]

Well it seems like a scuba tank is pretty much useless then, isn't it?
Thanks.

Wait, to clarify, lets not steer anyone away from using SCUBA tanks if they have a dive shop near them. IMO, SCUBA Tank are far more convienient then a Hand Pump, especially if you live close to a Dive shop.

For starters, first, most if not all of my 3000 PSI guns do not have a shooting sweet spot that starts at 3000 PSI. Many of my guns sweet spot start at 2800PSI and lower. Secondly,  I dont shoot my guns tanks down past 1200PSI. for me personally, not topping off my tanks to 3000PSI gives me way more then I need for my shooting. I have a dive shop 6 freeway miles and it take me less than 30 minutes to get my tanks filled at the local dive shop and back home shooting. It costs only $8, and if my SCUBA tank has 2000PSI or more in it, my dive shop does not charge for the fill, its free. best of all, they will fill it to 3200PSI.

When I get tired of fulling my gun up to only 2000PSI, I go back to the dive shop.

I tried the cheap YH compressors, but I was always way too concerned with blowing crud into my nice rifles. That and they were noisy as heck. Gave it away.  If the number of times I shoot goes up, Ill just get a second tank. They are real cheap on craigslist.

Leave hand pumping to the young bucks...

[CableStop]

My little 12v benjamin pump cost me $600 but I've used the heck out of it and it just needed it's first maintenance after a year or so of use.  It started squeaking so I regreased the wrist pin with some moly grease and it quieted right down, took less than an hour to take it apart and get it back together again.  I recently upgraded to a much larger Alkin compressor and ironically I had an o-ring blow out on it with 0.6 hours of run time on the clock.  Looking at the o-ring it had clearly been pinched during assembly, luckily it was just a connector in the whip and was an easy fix.  That said there is no comparison between the performance of the two compressors and I'm still very happy with the upgrade.