Length of SCBA hose, does size matter?

[deucelee]

I'm thinking this may be one of the few cases where bigger is not better.   

So I got a 4 foot hose from NorthShoreCompressors.  The thought was it would give me more flexibility having a longer hose.  It's rated for 6,000 psi.  It's got a .188" ID (3/16") so it's definitely not as thin as Joe's: "We have micro-bore hoses that are very FLEXIBLE, are much longer and have a inside diameter of only .070" (1.78mm).  1 FOOT of this hose has LESS AIR THAN  1 INCH of 1/4" ID  "Paintball" hose, so very little air is wasted (that means less pumping to fill your hose or filling your tank). "

The surface area is .003848^2" square inches for Joe's compared to .027759^2" for mine.  That's a 7 fold difference. 

Any idea what's the impact of this over hundreds of fills and bleeding 4 feet of this wasted air out? Or am I just being stupidly worry-sum? The chamber where the gauge sits probably has a TON more air that's going to be wasted anyway?

[vigilandy]

I'm thinking this may be one of the few cases where bigger is not better.   

So I got a 4 foot hose from NorthShoreCompressors.  The thought was it would give me more flexibility having a longer hose.  It's rated for 6,000 psi.  It's got a .188" ID (3/16") so it's definitely not as thin as Joe's: "We have micro-bore hoses that are very FLEXIBLE, are much longer and have a inside diameter of only .070" (1.78mm).  1 FOOT of this hose has LESS AIR THAN  1 INCH of 1/4" ID  "Paintball" hose, so very little air is wasted (that means less pumping to fill your hose or filling your tank). "

The surface area is .003848^2" square inches for Joe's compared to .027759^2" for mine.  That's a 7 fold difference. 

Any idea what's the impact of this over hundreds of fills and bleeding 4 feet of this wasted air out? Or am I just being stupidly worry-sum? The chamber where the gauge sits probably has a TON more air that's going to be wasted anyway?

Have you looked at the Ninja microbore hoses?  I got one for my dad's 90CI tank because the original was way too short.  I looked briefly, but couldn't find its exact dimensions.  For sure though it's smaller than my standard hose that came with the SCUBA yoke.

[deucelee]

Have you looked at the Ninja microbore hoses?  I got one for my dad's 90CI tank because the original was way too short.  I looked briefly, but couldn't find its exact dimensions.  For sure though it's smaller than my standard hose that came with the SCUBA yoke.

Thanks for the heads up Andy.  Good to know.  I just googled them and that's good to have as a option.

[amb5500c]

The shorter the hose, the less wasted air. But you don't want to be so short that it becomes inconvenient for comfortable filling. IMO. Mine is about 3' long, which is usually just right for me.
Richard

[ShakySarge]

The shorter the hose, the less wasted air. But you don't want to be so short that it becomes inconvenient for comfortable filling. IMO. Mine is about 3' long, which is usually just right for me.
Richard

x2 what Richard says

[vigilandy]

FYI I found the most convenient thing was to buy a Ninja microbore and take off the ASA fitting.   Runs about $35.  I needed the ASA fitting for bulk filling CO2 anyway so it was a deal.  The hose has 1/8" male NPT ends. 

[nglitz]

To try to answer the original question, the difference from your hose to a micro-bore is negligble.  Go shoot & enjoy.  You'll never notice the difference.

Norm

[deucelee]

To try to answer the original question, the difference from your hose to a micro-bore is negligble.  Go shoot & enjoy.  You'll never notice the difference.

Norm

Thank you Norm! Appreciate the confirmation!

[TimmyMac1]

There are two primary considerations here. The Length of the hose will be the chance for it to be transformed to a whip if you turn it on and do not have a hold of the end of the hose. Be very careful with lines that are longer than 10" and snapping the QC collar all the way as they can whip around violently if someone turns the valve on and the end is not restrained or properly connected. The greater the flow the worse it is when the things gets away or blows the QC apart.
The other consideration is the flow of a Microbore is more and more restricted the longer it is. This can counter the whip effect but the bleed event will not be as dynamic and the possibilities that the flow will be inadequate to seat some check valves has been an issue. Ninja and a lot of systems need flow to shuttle the inlet seal to the closed position as they do not utilize a spring. Bleeding as quickly as possible and pointing the gun down while bleeding can mitigate the problem by taking advantage of gravity.

TimmyMac1

[rsterne]

In terms of wasted air, a 4 foot hose with a 3/16" bore holds 22 cc of air.... On a gun like a Disco that holds 135 cc and needs only about 60 cc to refill it from 1100 psi to 2000, that means you will waste about 25% of the air every time you bleed the hose.... That means 25% fewer fills....

The same length microbore hose (with a 0.070" ID) would only waste 3 cc....

Bob