What exactly is the purpose of low and hi pressure ports?

[SunshineFish]

I've been doing some research regarding regs (mostly on-line) for my first purchase of one. There's one term that I don't understand: I keep coming across the term "low pressure" and "high pressure" ports. What exactly are these and why does it matter how many of each are available on a reg?

Also, what are the advantages/disadvantages of a first-stage that swivels and one that doesn't?

Any help would be much appreciated.

Sunshine

 

[Rick Murchison]

These are threaded holes in the body of the first stage that deliver either high pressure (whatever's in the tank) or low pressure (regulated) air at a constant 125-150 (approx - some second stages want intermediate pressures outside this range so the first stage is set to accomodate). The high pressure air goes to your submersible pressure gauge (to tell you how much pressure (air) you have left in your tank), while the low pressure air goes to your second stage regulator, your octopus second stage, your low-pressure inflator hose on your BC, and your dry-suit inflator.
Rick

 

[Campana]

On a regulator first stage with swivels, some of the low pressure ports are mounted on a separate part of the regulator body that can be turned. When hoses are attached to this part, such as your two second stages, the hoses can move a bit if they need to to give you more flexibility. For example, if you turn your head away from the side of your second stage, the first stage can swivel a bit to give you some more hose. That flexibility is the advantage of a swivel. The disadvantage of a swivel is that it is one more failure point. There has to be o rings in the swivel to keep it from leaking, and if one fails, you will get a bad air leak at the swivel point. That is why some cave divers won't use swiveling regulators. I have never heard of this actually happening, but it could. For that reason, I don't use swiveling regulators in caves. I have Scubapro Mk 16's, a non swiveling regulator first stage, for that. I also have Scubapro Mk 20's that do swivel for open water. I don't see that a swivel gives any real advantage, so prefer the Mk16's for the most part. The Mk 16 is a good regulator, not too expensive, and breathes just as good as the Mk 20. It is a Rodales' Scuba Diver "Testers Choice" because of it's breathing characteristics, and a "best buy" because of its relatively low price.

Happy researching!

Dave

 

[The Chairman]

The first post was completely correct... however, asn easy way to get it in your mind is...

high pressure port; non regulated, whats actually in the tank!

low pressure port; regulated, what your second stage and inflators use.

 

[SunshineFish]

Thanks everyone - your responses really helped me out a lot! I think I pretty much narrowed it down to which regulator I will buy.

 

[Tavi]

Originally posted by SunshineFish
Thanks everyone - your responses really helped me out a lot! I think I pretty much narrowed it down to which regulator I will buy.

Are you going to keep us in suspense, or are you going to tell us?

 

[SunshineFish]

LOL :lol: - I didn't know there was interest, sorry, I will lift the suspense.

Based on my budget, I've narrowed my choices to the Genesis GS-2000, Seaquest Apeks TX50, and the Scubapro MK16.

I'm going to make a visit to my LDS this week and check out their prices and also see what they have to say.

 

[Tavi]

I'm always interested in what others are usung and how it works for them. I think a lot of us are.
It looks like you've been doing your homework.

 

[Weezle]

I am looking right now at a scubapro mk18 or 20 with s380 primary and s190 backup, although I might get another s380 as backup - not quite sure yet. I will be diving with nitrox below 40% most of the time.

What do you guys dive with?

Joe

 

[Tavi]

I dive with an Apeks Tx-50 DIN with Tx-40 octo, My wife has the Tx-100 with Tx-40 octo. We both love what we have, But....... I've been eyeballin' the new ATX-200. It looks sweet, and it doesn't have the swivel first stage my Tx-50 has (is that a good enough excuse for a new reg?