Converting Apeks 1/2" to DIR 3/8" Hose

[docmartin]

grajan that's good info b/c i am in the process of converting to a dir hose set, too. now if you have a 1/2" hose and use the adapter to convert to 3/8" don't you need 2 adapters? one for the attachment to the first stage 1/2" port and one to attach the other end of the thinner hose to your second stage? maybe a stupid question but i am confused.

 

[Grajan]

It turns out that all second stage ports are the same so the issue is only at the primary end.

My only concern about this whole excercise is the possiblility of restricted flow going from a 3' x 1/2" hose to a 7' x 3/8" hose.

I assume there is going to be a slightly increased dynamic pressure drop but I'm not sure if it will be significant. I understand the output pressure of the first stage can be tweaked by a tech.

 

[wetman]

I was just looking at two hoses - one a half inch and the other the regular size. Hoses appear identical, the 1/2 seems to reduce pretty quickly to the same diameter that i see in the smaller hose (within an inch or so of the screw in portion). How can that possibly pose any benefit whatsoever.

On another note, have a couple plugs or converters handy and you're all set to do whatever you need to do with whatever hoses you have.

steve

 

[Grajan]

Technically hoses are supposed to be identified by their internal diameter.

If this is indeed the case with scuba hoses then the 3/8" ID hose has only 56% of the cross sectional area of the 1/2" hose. This is potentially significant.

My phnumatics is a bit rusty but one should be able to calculate the required flow rate for a typical stressed full breath and thence the pressure drop. I will look into it some time. I am assuming the DIR guys have addressed all this in producing their very detailed equipment specs.

 

[blackice]

a picture says a thousand words they say so here is a pic of both 1/2 and standard hoses.

http://www.thirteen28.com/holidays/manado/aaaa-Images/14.jpg

this is the set up I used in Manado recently.

I may have a relook at it and see if I can make it better by switching things around but the air on both the regs was good the main reg had very easy breathing at 30m and the adjustments were good - it allowed me to get just a little too much air so I turn it back a little and I'm getting a nice amount.

Next test is to try buddy breathing to see if teh supply of gas is reduced by both regs being used.

 

[RichLockyer]

Grajan once bubbled...
Technically hoses are supposed to be identified by their internal diameter.

If this is indeed the case with scuba hoses then the 3/8" ID hose has only 56% of the cross sectional area of the 1/2" hose. This is potentially significant.

But they aren't. They are identified by the diameter of the fitting connecting them to the 1st stage.
Even if the hose were to have a larger ID, it still chokes down to the same diameter hole where it enters the 2nd stage.

I've been using a 3/8" 7-foot hose for a couple of years now... no problems at all, and if I put the reg into freeflow it will blow ice crystals. Nothing wrong with that setup.

As far as rigging my Apeks, I put the original hose on my backup reg and the 7-footer on my primary. This routes perfectly since the 1/2" port is closest to my neck so the hose just makes a quick loop over my shoulder, while the 7' hose goes down along side the plate.

 

[blackice]

RichLockyer once bubbled...

...I put the original hose on my backup reg and the 7-footer on my primary. This routes perfectly since the 1/2" port is closest to my neck so the hose just makes a quick loop over my shoulder, while the 7' hose goes down along side the plate.

Now that's an idea I might have a look at my set up over the weekend and think about trying that - sounds good.

 

[Grajan]

As Rich says there does not appear to be a significant difference in the actual hoses so I ended up using a reducer and all 3/8" hoses.

It seems to work fine. I guess that is what most who use the long hose do as it is only the Apeks 1st that has the 1/2" port.

Anyway - thanks for all the ideas.

 

[RichLockyer]

Grajan once bubbled...
As Rich says there does not appear to be a significant difference in the actual hoses so I ended up using a reducer and all 3/8" hoses.

It seems to work fine. I guess that is what most who use the long hose do as it is only the Apeks 1st that has the 1/2" port.

My old Conshelf XIV has a 1/2" port for the HIGH PRESSURE hose!

I'd avoid the reducer if possible. Especially if running doubles, the 22" hose in the DIR kits is too short for the backup and you can't turn your head to the left. They work okay for singles, but you really don't need it. I'd rather have a little extra hose sticking out than the extra O-ring.

 

[gaustad]

Rich,

I'm a newbie, and not considering DIR, but it seems that having the second readily available around my neck and being able to pass a long hosed primary to my buddy is safest setup. That said, I'm curious how you dealt with the long length of the orginal hose for use as a necklaced second. Could you describe in a little more detail what you mean by a "quick loop" over your shoulder. I am also curious as to whether the 7' 3/8" hose is connected to the left or right side of the first stage. I am using the 3/8" on the right side for my drysuit hose. If its on the left do you route the 7' hose down and across the plate to get it on the right?