Hypothetical question on transferring air between a scba tank pcp air venturi t

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rodjava

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Sep 6, 2021
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San Francisco California, 94134 United States
www.allcalibers.com
This is a hypothetical question.

Say for example, I have 2 tanks.
One is SCBA tank with only 2000 psi in the tank and with a max 4500 psi.
Second is standard PCP air tank like the 98 cubic inch Air Venturi which is full of air at 4500 psi.

Is it possible to transfer air from the full tank with 4500 psi, to the tank with only 2000 psi?

The goal is to top off the tank with only 2000 psi to 4500 psi. What hardware would be needed to achieve this hypothetical task?

Again, this is a hypothetical question. If you can keep your comments "on topic" it would be appreciated.

Rod in San Francisco
 
If they're similar sizes and you just hook them up, and open the valves, they'll arrive at an equal pressure less than what you started with in the higher pressurized tank. 

Again, if they're equal sizes you'll have something like 3100-3200psi in both. 

I do similar with my little three tank cascade system that consists of a 19cf scuba tank, a 80cf scuba tank and a big 60min SCBA tank. 

If I start around 4200 with the 60 min SCBA and hook it up to the 19cf SCUBA and open the valves, it'll bring the pressure in the 19cf up to 3100psi from say 2500 psi and there will still be around 3700-3800 left in the bigger tank. That's due to the large difference in tank capacity in this particular example. 
 
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If they're similar sizes and you just hook them up, and open the valves, they'll arrive at an equal pressure less than what you started with in the higher pressurized tank. 

Again, if they're equal sizes you'll have something like 3100-3200psi in both. 

I do similar with my little three tank cascade system that consists of a 19cf scuba tank, a 80cf scuba tank and a big 60min SCBA tank. 

If I start around 4200 with the 60 min SCBA and hook it up to the 19cf SCUBA and open the valves, it'll bring the pressure in the 19cf up to 3100psi from say 2500 psi and there will still be around 3700-3800 left in the bigger tank. That's due to the large difference in tank capacity in this particular example.
Click to expand...

Franklink,

I was anticipating a logical explanation like yours. Thank you as it makes sense. I would need a type of transfer hose with a DIN300 and CGA-347 on the ends to hypothetically make it work.
 
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Some may frown on the safety aspects of doing it this way, but if you have a fill station for each tank, with the fill whips ending in female fosters, than all you need is something like this.....

https://www.pyramydair.com/product/air-venturi-4500-male-to-male-quick-disconnect?a=8492

to connect the tanks together. 

My male to male foster fitting is slightly different than the one in the link but that's how I move air from tank to tank. 
 
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Here is another way to connect your two tanks...

https://airtanksplus.com/product/tman-pcp-tee-block-air-splitter-female-foster-to-2-male-foster-fittings/

but you will need a dead head to make the Y splitter work.

https://airtanksplus.com/product/dead-head-male-foster-fitting/

I have the Y splitter and highly recommend it if you're going to be cascading, even if only for a small personal use system of 2 or 3 tanks. You can get a lot more mileage out of the same amount of air with a Y splitter and two tanks. 
 
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At minimum a connector for each tank and a bleed valve in between. However, you need to add more to allow flexibility and control such as a hose to allow better positioning between the two tanks. Maybe a pressure gauge so that you know the equalized pressure. Maybe a flow control valve if the tank valves are not fine enough to keep the airflow slow and minimize thermal stress.

Depending upon what fill hoses you have now you might be able to adapt something using your current fill hoses with only the purchase of one or a couple adapters. For example if you had two SCBA tanks with fill hoses ending in QD foster female connectors then you could buy a double-ended foster male connector and hook both of them together.
 
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At minimum a connector for each tank and a bleed valve in between. However, you need to add more to allow flexibility and control such as a hose to allow better positioning between the two tanks. Maybe a pressure gauge so that you know the equalized pressure. Maybe a flow control valve if the tank valves are not fine enough to keep the airflow slow and minimize thermal stress.

Depending upon what fill hoses you have now you might be able to adapt something using your current fill hoses with only the purchase of one or a couple adapters. For example if you had two SCBA tanks with fill hoses ending in QD foster female connectors then you could buy a double-ended foster male connector and hook both of them together.
Click to expand...

Runner57us, Thank you for chiming in with your suggestions. Your idea is similar to another helpful members suggestions.

Rod in San Francisco
 
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