Why a 1/2" port?

[Freeflyer]

Hi, could someone explain why some manufacturers put a 1/2" port on their 1st stages, while others do not.

I'm looking at the apeks range and one has it, one doesn't. Looking to make an informed decision.

Thanks,

J.

 

[Bob3]

The 1/2" is for increased performance during deep diving, when the breathing gas gets thicker.
Most folks don't think it makes that much difference, as by the time you get deep enough to have your air get thick, you're going to be thinning it out with helium anyway.
It "might" become an issue past 600'.

 

[Don Burke]

I have a couple of USD regs from the 80s with all of the LP ports 1/2 inch.

It might be a legacy thing.

 

[PurduEE]

Mares still has bigger ports on their regs for the primary second. MR22, V32 both have it. It's just another part (1/2 to 3/8 hose) that you need to carry in your save-a-dive kit...

I believe that some other brands (Apeks maybe?) still use 1/2 on some of their ports as well.

 

[Hallmac]

is to slow the high volume air flow down and make it easier to prevent freeze up.

Hallmac

 

[TDunbar]

On the Mares regs there is a preferential 1/2" port for the primary. Inside this port is a tube - part of the DFC system - that will prevent the use of just any old 1/2" hose. The DFC is part of the reason the regs are such easy breathers. While you can buy an adapter to allow the use of generic hoses, the adapter destroys the reason you bought the reg in the first place - breathability.

Todd

 

[RichLockyer]

TDunbar once bubbled...
While you can buy an adapter to allow the use of generic hoses, the adapter destroys the reason you bought the reg in the first place - breathability.

That's funny... I have a 3/8" 7 foot hose on my Apeks reg and my buddy dives his with the 1/2" stock length hose.

Neither of us can tell the difference at 140 on air.

 

[Freeflyer]

I've been trying to decide between the apeks first stages that have the 1/2" port and the swivel turret and the 3/8" ports and no swivel.

Guess the flow rates aren't going to make a difference so it's down to the swivel. The non-swivel is $60 more. The reasons I see to pay the extra are

1. No swivel eliminates a possible failure point (but I've not seen any incidents of that failing any way)

2. Everything has the same connection, therefore redundancy is reduced slightly (although if you're reg goes, unless you have a spare, you're not diving that day anyway, unless they have a spare on the boat)

I'm tending towards paying the extra for the non-swivel with identical ports all round.

Comments/suggestions welcome.

J.

 

[TDunbar]

RichLockyer once bubbled...

That's funny... I have a 3/8" 7 foot hose on my Apeks reg and my buddy dives his with the 1/2" stock length hose.

Sorry, I was referring to Mares regs. They -Mares regs with 3/8" adapter- still breath fine IMO, just not as easily as w/o the adapter. I haven't work on any Apeks regs.

Todd

 

[RichLockyer]

TDunbar once bubbled...
Sorry, I was referring to Mares regs. They -Mares regs with 3/8" adapter- still breath fine IMO, just not as easily as w/o the adapter. I haven't work on any Apeks regs.

I knew you were referring to Mares, but my point was that Apeks and everyone else who uses a different size fitting claims that it is for better performance/breathability.
Last time I looked, everyone except Poseidon use the same connection to the 2nd stage and it isn't 1/2"

Matter of fact, the O-ring sealing the 2nd to the hose is a 010, which is smaller than the 011 used to connect a standard 3/8" hose to the 1st stage, and of course, much smaller than the 013 used for the 1/2" ports. This indicates logically that the opening on the 2nd stage end of the LP hose is smaller than the opening on the 1st stage end.

Given the flow that high performance regs are capable of and the relatively limited flow that we are capable of using, any difference in performance attributed to the different port design would fall under the category of "viewable on a breathing machine but imperceptible to the diver"... certainly within recreational depths.