Reg Performance with Long Hose

[RockPile]

“I don't want to breathe my long hose, I want to have the best performance regulator in my mouth and the long hose decreases this performance.”

With literally thousands of deep exploration dives accomplished by divers breathing the long hose, the performance argument seems rather a moot point. Yet, if one were to insist that the reduction of performance is unmanageable, it seems like a poor solution to leave the stressed, out of air diver gasping for air on this lower performance regulator so you can have a more relaxed dive. Your best performance regulator must be on your long hose and if its performance is unacceptable in a relaxed situation then it is certainly inappropriate to suggest that your stressed dive buddy is better prepared for this increased resistance. The one thing to be clear on is that if the regulator you try to provide to an out of air diver is in any way substandard, you will be giving up the regulator in your mouth and your ability to handle that situation may make the all the difference.”
-Jarrod Jablonski

I just finished reading The DIR Philosophy and thoroughly enjoyed it. I’m most interested, though, in the above paragraphs. His reasoning in the second paragraph about why the decrease performance complaint should be moot seems solid enough. However, I can’t quite assess whether or not I completely agree until I know what kind of performance reduction we are talking about first.

I’m dead certain hard numbers have been established, I just can’t seem to find them. I cruised all the usual DIR sites and couldn't locate anything measuring this. Could anyone provide these for me?

I didn’t post this out in the open because I didn’t want the thread to get scrambled into a debate. I’m just looking for the science behind the decisions.

JB

 

[jonnythan]

I never felt the need to look for measurements when I can't discern any difference whatsoever between identical regs (one on my 7' hose and one on my 24" hose) at 100 feet on air. I've done this on high performance Apeks regs and decidedly low performance Sherwood regs.

It's not worth dedicating brain cycles to. There is no discernable difference whatsoever.

 

[PhilEllis]

“I don't want to breathe my long hose, I want to have the best performance regulator in my mouth and the long hose decreases this performance.”

We certainly don't have a machine that will measure dynamic Work of Breathing, but we do have dynamic testing capability. In our store, we have batted around the prospect that a long hose probably affects the performance of a regulator. If we get the chance today or tomorrow, I think we will actually test a regulator with and without the long hose and see what happens at the higher flow rates. The results might be interesting. If we are able to get this testing done, I will post the results here. Thanks.

Phil Ellis
Dive Sports Online
www.divesports.com
(800) 601-DIVE

 

[RockPile]

We certainly don't have a machine that will measure dynamic Work of Breathing, but we do have dynamic testing capability. In our store, we have batted around the prospect that a long hose probably affects the performance of a regulator. If we get the chance today or tomorrow, I think we will actually test a regulator with and without the long hose and see what happens at the higher flow rates. The results might be interesting. If we are able to get this testing done, I will post the results here. Thanks.

Killer! I'm glad I asked.

Thanks, Phil.

JB

 

[OWSI176288]

I agree with Jonnythan. I use Apek DS4 as first stages with a TX50 on my 7 foot long hose and a ATX 50 as my bungeed backup. And I can't tell the difference.

So as long as you have a good performing reg, this shouldn't be a problem. Plus with helium added to the mix, just about any reg will breath easy at depth. In fact you need to worry about the opposite.

 

[GDI]

Pete DeCoates and I have done this testing at Zeagle on their test bench and there is really no difference in the perfomance of a reg with a long hose to that of a short hose. The question of having a equal secondary to that of the primary is a sound thought for any diver. Most tech divers will have the same models of regs for their back gas so this concern has been made null and void. By the way I have the same regs for short and long hose use and there is no discernable difference in their performance at any depth that I have dived (in excess of 300 ft). Sport divers diving within OW limts may have differing performance regs /second stages. This may be a result of cost or model matching, for whatever reason their alternate performs at a lessor grade.

While I personally agree with JJ's suggestion of having both regs of equal performance let me offer a countering perspective: Something to consider from the average OW diver point of view is that the alternate airsource should it be one of lessor performance may not be a factor in dealing with a stressful diver for two reasons

1: the stressful diver in the OOA situation may take the reg from the donor diver's mouth. The donor diver may be more relaxed then a stressful diver needing air and maybe able to handle the lessor performance of a alternate second stage as they make thier controlled ascent to the surface

2: the stressed diver who truly is OOA will have initially a heavier than normal breathing rate that when using a lessor performing alternate will overcome the reg's breaking pressure allowing it to deliver air comfortably within the depth ratings for recreational diver limits

The best scenario though is to have compatable regs (include second stages here) that will deliver the air with the same performance level, the highest performance level as possible. Some regs/second stages perform much better than others of this there is no question. Many of the better performing regs are not all that expensive as some may think ($600 average range) Hey its your life get the best you can buy. Before you buy test breath the regs you want wet at varible depths to see how they perform. Just a thought?

 

[Charlie99]

If we get the chance today or tomorrow, I think we will actually test a regulator with and without the long hose and see what happens at the higher flow rates. The results might be interesting. If we are able to get this testing done, I will post the results here. Thanks.

Hopefully you have a 60' snuba hose around
Then you might be able to detect a very slight difference in WOB at normal flow rates.
A number that might be significant enough to actually measure is the IP drop at the 2nd stage vs. length of hose.


Rockpile -- don't forget that the long hose is carrying the intermediate pressure at around 130psi. Particularly with a good quality balanced 2nd stage, a few psi drop in the hose isn't going to be noticed. It's not like you're trying to suck air down the length of the hose.

 

[RockPile]

Phil, don't forget about us. My roommate and I are waiting on pins and needles.

JB

 

[rmannix]

You have the same lung capacity no matter what hose length you use. If anything the long hose provides a larger amount of IP air and would probably enhance performance on a marginal first stage and be imperceptible on a high flow one.
Connect reg to tank, turn air on and charge hoses. Now turn the air off and see how many breaths you get from the long hose.
Repeat using the short hose.

 

[PhilEllis]

Phil, don't forget about us. My roommate and I are waiting on pins and needlesJB.

We did the test yesterday afternoon. Gary used a new XTX-200 regulator for the test. Same first stage, same second stage, same first stage port. One test with the standard 28" hose and one test with the 84" hose (the long hose was a high-quality Dive Rite 84" hose). The initial cracking effort of this regulator was set quite high right out of the box from the factory, approximately 1.8 inches of water effort (a PERFECT example of why it is important to have the dealer do pre-delivery set-up and adjustment on a new regulator....it should have been set at approximately 1.0 inches of water. I happen to know an online store that ALWAYS tests and adjusts new regulators before shipping them, including the complete dynamic flow rate testing....see if they can do that at the New York online store). We did not notice any measurable difference in the effort required to deliver air at high volumes. At a flow rate of 10 CFM, both tests required about the same vacuum effort. At 25CFM, both tests required about the same vacuum effort. At every flow rate in between, we noticed no differences in the effort required to maintain the flow. There was a difference in the intermediate pressure drop at the high sustained flow rates. Not a lot, but a difference of about a 5 PSI larger drop at a flow rate of 25 CFM with the long hose. However, this would not affect the "performance" of the regulator with the two set-ups. Since I don't sell the "cheap" long hoses, we didn't have one of those to test, but I wouldn't expect that to make any difference either. The bottom line, from the viewpoint of a country-boy dive store owner, hose length makes no difference in the performance of any particular regulator. Anyway, thought you might be interested. Thanks.

Edit: Additional Note Added After a Little More Thought: the longer hose WOULD make a little bit of difference in the "lag" in the first stage. "Lag" is the time between when the second stage cracks and begins to deliver air and when the first stage "realizes" that air has been removed and opens to replenish air to the intermediate side of the regulator. This time is VERY VERY short (1/1000's of seconds) and would never be noticable except in cheap, poorly designed regulators. In a cheap regulator, this can sometimes result in a "burst" of air while you are breathing from the second stage. In a high-quality regulator, this action will be very smooth and will occur without the diver taking any notice of it.) Anyway, thought I should make that note.

Phil Ellis
Dive Sports Online
www.divesports.com
(800) 601-DIVE