1st-stage LP 'T-adapter', does it reduce LP hose flow rate?

[scubafanatic]

Hello,
I've got an Apeks 200XTX, and on one of the 1st-stage LP ports, I'm running both a primary 2nd stage LP hose and a BC inflator hose....but I'm concerned that the gas path through the T-adapter may not have the same flow rate as if I were to just screw the primary 2nd-stage hose directly into the same LP 1st stage port....so, am I losing any performance in this configuration ?

Thanks!

Karl

 

[DA Aquamaster]

Yes and no.

The "no" argument:

The area of the orifice and/or the working range between the seat and orifice in the second stage is the choke point in terms of flow rate for the regulator, so a flow restriction farther upstream has very little impact on flow rate once the flow is established.

The "yes" argument:

Depends on the reg and the specific port. Some ports have a better flow path than others and a T adapter can mess with the flow path, cause turbulence, back pressure etc - although I'd argue the flow rate through a LP port and a T is still more than you could push through the average second stage. The question mostly becomes whether you can blow enough through the inflator and second stage at the same time to reduce the flow to the second stage enough to be noticeable. I'd argue that you can't, but inhaling and inflating at the same time is bad form so its a moot point anyway.

However I would avoid a T adapter as they can potentially put a great deal of stress on a single fitting and while I seldom make an issue of "failure points", a T adapter is a huge one. There are better solutions to the problem.

 

[scubafanatic]

Hi DA Aquamaster,

I was hoping you'd spot my thread! I'm running my primary 2nd stage through the 'T' such that the hose is receiving a 'straight' flow path...and I'm running by back-up 'dual' inflator off that same 'T' at a 90 degree angle downward angle, but I'm not too worried about that, as the inflator is the back-up one, and I'm sure it will be able to flow far more gas than I'll ever run through it....also, being the back up inflator, it will be a rare 'emergency' situation where I'm breathing off the primary and pushing lots of gas through the back up inflator simultaneously......so it sounds like my configuration will be OK...aside from the 'stress point' issue.......but I don't see an elegant way around that, and I've thought about it a LOT! ....my dive buddy has 'our' UW digital camera, so unfortunately I can't post a photo of my reg configuration.....I've done a lot of custom work on it to get all the hoses routed cleanly...so I think I'm stuck with using a 'T'.

Karl