Filling with 2 Tanks. Will this work?

[Marauder .22]

Greetings,

Will this method of filling my Marauder .22 with two tanks work?

Crosman Fill Calculator being used: http://www.crosman.com/university/fill-calculator

Fills for a synthetic Marauder .22 using 2 different filling stations.
1: Scuba 80 Cu Ft tank (Water Volume 677 cu in w/3500 PSI).
2: Air Venturi Carbon Fiber 90 Cu In w/ 4500 PSI

According to the fill calculator:
Scuba 80: 3000 psi from 2000 psi = 25 fills
Air Venturi: 3000 psi from 2000 psi = 10 fills
Total fills would be 35 fills.

Now let’s change some fill levels into the Marauder.
Scuba 80: 2800 psi from 2000 psi = 44 fills
Air Venturi: 3000 psi from 2800 psi = 50 fills

Does this mean that I can fill up to 2800 psi from 2000 psi with the scuba tank and top off with my air venture from 2800 psi to 3000 psi?
If so, then I can get at least 44 fills by starting with the scuba and topping with the Air Venturi. Am I theoretically correct? I do realize that I will lose some air during each fill when I vent the line after the fill.

If this will work, I plan to purchase a used scuba 80 3500 psi from my local scuba shop in my town. He can only fill to 3500 psi. I already have an Air Venturi 4500 psi but the closest paintball shop is 20 miles from me, so I'm hoping to reduce the number of trips to them.
Thanks,

[RayK]

Yes, it is called "cascading"

It is a bit of a pain to do all the hose changing.

You can make/buy a rig to make it easy. SHOOTIN'IT posted some pictures of how he made one with two cheap scuba fills.

You'll still get lots of partial fills too.

And you can re-tune your gun for 2500 psi fill to get even more fills from tanks, but the peak power will be lower.

Ray

[Marauder .22]

Thank you for the feed back. I will be picking up the scuba this Monday on a rental basis at $12.00 per day. If I like it, he will credit the rental days to the purchase price which is about $250.00 for a new unit but hasn't been used for a few years. I do have a scuba to Air Venturi adapter for I used his facility to fill the Air Venturi to only 3500 psi. His limitations. I am fortunate to be able to set up a range in my cellar which gives me a 60 to 70 feet of target practice which will allow me to test every night after work. Will post my findings on this cascade setup.

Thanks for the feed back.

[PB_Matrix]

$250.00 for tank that will need a hydro test soon doesn't sound like a very good deal.......

[RayK]

The high pressure steel tanks are not cheap as the 3000 psi aluminum tanks.

But that is a good point about possibly needing a hydro. They are valid for 5 years and around here they cost about $50 each test, so check the date of last hydro.

If you have a place that will fill 4500 psi, the SCBA tanks are worth paying more money for (at least for PCP air fills). They are much lighter than SCUBA tanks and you get tons more gun fills per tank fill.

Ray

[Marauder .22]

Thank you for the tips. Love to purchase a 4500 psi scuba tank and you said tons of loads for the Marauder .22. What cu ft capacity are you referring to and how many loads to a full 3000 psi?

[int3man]

Thank you for the tips. Love to purchase a 4500 psi scuba tank and you said tons of loads for the Marauder .22. What cu ft capacity are you referring to and how many loads to a full 3000 psi?

Hi Marauder .22,
The highest Scuba Tanks that I know of are called HP SCUBA and are a DIn or European valve. They are rated at a max of 3800 PSI. Unless things have changed. The 4500 PSI tanks are a Carbon Wrapped SCBA Tanks with a 15 year life span, used by the Fire Departments.
The difference between the two is the U for Underwater. Also the HP SCUBA tanks are Steel.

Michael :- )

[RayK]

You can do the what-if scenarios yourself here
http://www.americanairrifle.com/tank.htm

Using a tank size of 80 cubic feet, a gun fill at 3000 psi from 2000 psi, and 215 cc for the Marauder airtube.

You would get 0 full fills from a 3000 psi tank, 22 fills from a 3500 tank, and 51 fills from a 4500 psi tank.

Of course, you would get lots more partial fills when your tank hits 3000 psi, but those will be the same for all three scenarios.

Tune your gun for a 2500 psi fill and refill at 1500 and your fills shoots way up for all three, e.g., you can get 26 full fills from a 3000 psi tank, 44 from the 3500 psi tank, and 69 from the 4500 psi tank.

You can see why the higher pressure tanks are so popular, but you must have access to a compressor that will fill that high.

Ray

[Marauder .22]

Done. Today I purchased a 80 cubic feet, steel tank, filled to 3500 psi which has been tested and I am good for 5 years. Cost was $250.00 plus Mass tax. So it cost me $265.83. As mentioned in my post, I should realize 44 fills, give or take, by cascading this tank along with my Air Venturi 90 Cu In 4500 psi. That said, filling from the Scuba tank and topping of with the Air Venturi is a piece of cake. They both have the necessary fill connections to attached to my Marauder. Refilling the scuba will cost about $7.00 and the Venturi is about $4.00. To me, this is workable for my needs. Thank you for your comments for they certainly helped me to ask the right questions and make the decisions for my needs.

[RayK]

One cool thing about that steel 3500 tank is it does not have a limited lifetime like the carbon fiber tanks have.

As long as it passes hydro every 5 years, it is still good to use. I have a 120 cubic foot 3500 steel tank that must be over 25 years old and it is still passing hydro every 5 years. Sadly, it is heavier than a lead brick. The SCBA tanks are pretty light by comparison.

Ray