Dual Pony Tanks?

firemandiver · 6th November 2007, 20:36

I'm thinking of adding a second 13cf pony tank to my Dolphin for both balance and the increased air supply. I'm wondering if I can make up a short HP hose and run the first stages in series, HP port to HP port, so there are two 1st stages, but only one 2nd stage(actually an Air 2). I know the two tanks would equalize when the valves are opened, but I would still have 26cf of air. I believe the HP port on a 1st stage is straight through with no pressure reduction. Has anyone tried this, or is there a problem with my idea? Any help would be great. Thanks, FD.

**Dsix36** · 6th November 2007, 21:09

It should work fine. I used to fill my 13 from my 120's with a whip that was made to screw into the HP port of the Draeger regulator.

I always filled very slowly so I am not sure about restrictions though.

**Freef** · 6th November 2007, 21:37

Why not get a larger tank that you can use for either deco or bailout? Or a larger tank and do away with the pony?

I use a 7L/232 bar tank sideslung on the left [more balanced as the 3L/232 is on the right which supplies my suit gas and is used for deco. Deeper bailout is from the 3L which is filled with air.

I also have a 10L/232 with an H valve that I occasionally use. I still need to sort a first stage to use with it though. The disadvantage is that if you are gas matching then the tank cannot be safely breathed from at depth.

If you have a hose between the two regs, it is a vulnerable point. If it became damaged and you couldn't isolate it you would lose all your bailout.

4ster · 7th November 2007, 01:30

I sort of use this setup when diving with the 40% jet, because the mix tank I use is larger (longer) and a 19cf pony will not fit. I have a unique first stage regulator that has an internal check valve so that gas can only flow one direction, if in the unlikely event the HP hose between the ponys breaks then only one pony bottle empties. You might be able to find a check valve that screws into a first stage HP port.

I find that I feel significantly "wider" with a pony on either side. A side slung bottle will have a lot more bail out gas and can be moved around to where it is most comfortable. Probably a simpler, better way to go.

**Freef** · 7th November 2007, 21:32

Hopefully I will be in with both a 5L/3L/7L stage set up on Sat, and the 10L with trimix

at last, but I won't be running a seperate reg off of that tank.

If I am then I will get some pictures of the set up I use.

teomannaskali · 7th November 2007, 22:16

Do a low pressure connection between the 2 regulators. And then set one of the reg's IP's slightly lower than the other. That way you first use one tank and then use the other.

You can also swithch the mix by swithching one tank off and the other on.

This is a very celver design I think and it is used on a Submatix in SCR mode.

Teoman

firemandiver · 7th November 2007, 22:55

I'm not real fond of having hang tanks slung all over me. It gets in the way of spearfishing. I'm not too worried about 4ster's concern of it being a wide set up, either. I'm 6ft, 240, so I'm a big guy. I shouldn't have any problem with that. I am very interested in the check valve idea. That would cover the "what if a hose bursts?" angle. I've seen them for LP but I have never seen one for HP. Anybody got any idea where to find such a thing? I'm also intersted in the LP option, as Teoman suggested. That seems to be the least risky, and would also allow for some options with the possibility of different gasses. I'm really not planning on getting that far into it yet. I'm mainly looking for the increased air supply in case of a bailout situation. If I had to ascend from 130ft or so, a 13cf is not gonna last too long, especially if I had a problem or a deco obligation. Thanks for the advice so far, and looking forward to more input on this. FD.

**Dsix36** · 8th November 2007, 00:33

Another thing to consider, if using LP and there was a hose failure it is still possible to save some of the gas by turning the tank off. With HP and small tanks, they will drain very quickly in the event of a hose failure.

**Freef** · 8th November 2007, 16:31

Quote: (Originally Posted by teomannaskali)

This is a very celver design I think and it is used on a Submatix in SCR mode.Teoman

I think that the Azimuth SCR uses the same principle.

stumpy's widgets · 9th November 2007, 04:55

The Azimuth uses two separate regs. so the LP is switched you have the choice of one or the other. In a box around here somewhere I have several K valves with a HP port which would allow a pressure gauge to screw into the tank verses the Reg. I have 5\16, 3\8 and 1\2 machine thread Swagelok 1\4 tube fittings you could get a Swagelok spring loaded check valve say 2 LB so would create a small differential or could be 250 LB sort of reserve in one tank. The checks I'm thinking of are rated at 10,000 PSI.

6th November 2007, 20:36	#1 (permalink)
firemandiver Let's Go Diving! Current Rebreather/s: Dolphin Home Build Other Rebreather/s: Dolphin Home Build Join Date: Sep 2007 Location: gulfport, ms Posts: 144	Dual Pony Tanks? I'm thinking of adding a second 13cf pony tank to my Dolphin for both balance and the increased air supply. I'm wondering if I can make up a short HP hose and run the first stages in series, HP port to HP port, so there are two 1st stages, but only one 2nd stage(actually an Air 2). I know the two tanks would equalize when the valves are opened, but I would still have 26cf of air. I believe the HP port on a 1st stage is straight through with no pressure reduction. Has anyone tried this, or is there a problem with my idea? Any help would be great. Thanks, FD.
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6th November 2007, 21:09	#2 (permalink)
Dsix36 Going Down? Current Rebreather/s: Optima Other Rebreather/s: Join Date: Aug 2007 Location: Deerfield Beach, Florida Posts: 961	Re: Dual Pony Tanks? It should work fine. I used to fill my 13 from my 120's with a whip that was made to screw into the HP port of the Draeger regulator. I always filled very slowly so I am not sure about restrictions though. __________________ THE MORE THAT I LEARN, THE MORE THAT I STILL NEED TO LEARN!!!!!!
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6th November 2007, 21:37	#3 (permalink)
Freef Custom Title Disallowed! Current Rebreather/s: Dolphin Other Rebreather/s: Dolphin Join Date: Jan 2006 Location: Land of the Freef, UK. Posts: 1,356	Re: Dual Pony Tanks? Why not get a larger tank that you can use for either deco or bailout? Or a larger tank and do away with the pony? I use a 7L/232 bar tank sideslung on the left [more balanced as the 3L/232 is on the right which supplies my suit gas and is used for deco. Deeper bailout is from the 3L which is filled with air. I also have a 10L/232 with an H valve that I occasionally use. I still need to sort a first stage to use with it though. The disadvantage is that if you are gas matching then the tank cannot be safely breathed from at depth. If you have a hose between the two regs, it is a vulnerable point. If it became damaged and you couldn't isolate it you would lose all your bailout. __________________ David. Currently owner of two differently sized ankles.
(Offline)

7th November 2007, 01:30	#4 (permalink)
4ster Addicted to Oxygen Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Mar 2006 Location: Arlington, Washington Posts: 286	Re: Dual Pony Tanks? I sort of use this setup when diving with the 40% jet, because the mix tank I use is larger (longer) and a 19cf pony will not fit. I have a unique first stage regulator that has an internal check valve so that gas can only flow one direction, if in the unlikely event the HP hose between the ponys breaks then only one pony bottle empties. You might be able to find a check valve that screws into a first stage HP port. I find that I feel significantly "wider" with a pony on either side. A side slung bottle will have a lot more bail out gas and can be moved around to where it is most comfortable. Probably a simpler, better way to go. __________________ Steve "My problem is that I have trouble reconciling my gross habits with my net income." Errol Flynn
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7th November 2007, 21:32	#5 (permalink)
Freef Custom Title Disallowed! Current Rebreather/s: Dolphin Other Rebreather/s: Dolphin Join Date: Jan 2006 Location: Land of the Freef, UK. Posts: 1,356	Re: Dual Pony Tanks? Hopefully I will be in with both a 5L/3L/7L stage set up on Sat, and the 10L with trimix at last, but I won't be running a seperate reg off of that tank. If I am then I will get some pictures of the set up I use. __________________ David. Currently owner of two differently sized ankles.
(Offline)

7th November 2007, 22:16	#6 (permalink)
teomannaskali Custom Title Allowed! Current Rebreather/s: Home Build Other Rebreather/s: Not Bought Yet Home Build Join Date: Feb 2006 Location: Istanbul TR Posts: 350	Re: Dual Pony Tanks? Do a low pressure connection between the 2 regulators. And then set one of the reg's IP's slightly lower than the other. That way you first use one tank and then use the other. You can also swithch the mix by swithching one tank off and the other on. This is a very celver design I think and it is used on a Submatix in SCR mode. Teoman
(Offline)

7th November 2007, 22:55	#7 (permalink)
firemandiver Let's Go Diving! Current Rebreather/s: Dolphin Home Build Other Rebreather/s: Dolphin Home Build Join Date: Sep 2007 Location: gulfport, ms Posts: 144	Re: Dual Pony Tanks? I'm not real fond of having hang tanks slung all over me. It gets in the way of spearfishing. I'm not too worried about 4ster's concern of it being a wide set up, either. I'm 6ft, 240, so I'm a big guy. I shouldn't have any problem with that. I am very interested in the check valve idea. That would cover the "what if a hose bursts?" angle. I've seen them for LP but I have never seen one for HP. Anybody got any idea where to find such a thing? I'm also intersted in the LP option, as Teoman suggested. That seems to be the least risky, and would also allow for some options with the possibility of different gasses. I'm really not planning on getting that far into it yet. I'm mainly looking for the increased air supply in case of a bailout situation. If I had to ascend from 130ft or so, a 13cf is not gonna last too long, especially if I had a problem or a deco obligation. Thanks for the advice so far, and looking forward to more input on this. FD.
(Offline)

8th November 2007, 00:33	#8 (permalink)
Dsix36 Going Down? Current Rebreather/s: Optima Other Rebreather/s: Join Date: Aug 2007 Location: Deerfield Beach, Florida Posts: 961	Re: Dual Pony Tanks? Another thing to consider, if using LP and there was a hose failure it is still possible to save some of the gas by turning the tank off. With HP and small tanks, they will drain very quickly in the event of a hose failure. __________________ THE MORE THAT I LEARN, THE MORE THAT I STILL NEED TO LEARN!!!!!!
(Offline)

8th November 2007, 16:31	#9 (permalink)
Freef Custom Title Disallowed! Current Rebreather/s: Dolphin Other Rebreather/s: Dolphin Join Date: Jan 2006 Location: Land of the Freef, UK. Posts: 1,356	Re: Dual Pony Tanks? Quote: (Originally Posted by teomannaskali) This is a very celver design I think and it is used on a Submatix in SCR mode.Teoman I think that the Azimuth SCR uses the same principle. __________________ David. Currently owner of two differently sized ankles.
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9th November 2007, 04:55	#10 (permalink)
stumpy's widgets New Member Current Rebreather/s: Dolphin Azimuth Home Build Other Rebreather/s: Dolphin Azimuth Home Build Join Date: May 2007 Location: USA Washington(State) Posts: 33	Re: Dual Pony Tanks? The Azimuth uses two separate regs. so the LP is switched you have the choice of one or the other. In a box around here somewhere I have several K valves with a HP port which would allow a pressure gauge to screw into the tank verses the Reg. I have 5\16, 3\8 and 1\2 machine thread Swagelok 1\4 tube fittings you could get a Swagelok spring loaded check valve say 2 LB so would create a small differential or could be 250 LB sort of reserve in one tank. The checks I'm thinking of are rated at 10,000 PSI.
(Offline)

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