Questions about pressure of regulator

[declan long]

Hi Everyone

So last night i was having one of them sleeplees nights when thourghts just roll around in your head. I was thinking about intermidiate presures and abient pressure and 1st and second stages and how they worked. I have a few questions about this:

So the job of the 1st stage is to take high pressure from the tank and deliver to the second stage at an intermidiate pressure at give or take ten bar, So if you was at 9o m where the pressure is ten bar would this still work or is there a difference of balanced or unbalnaced regs or diaphram or piston, could you clear this up?

Why not just have a hose like on a blending system without a 1st stage and deliver gas at high pressure to a second stage and let that change the pressure to ambient preeure and breathe that from a scuba tank. meaning no first stage?

Also i read that stictly speaking you can not use a three hundre bar reg on a two thirty two bar tank, why? is there an adapter? could some one clear all this up please?

thank
declan long

 

[dfx]

The intermediate pressure is 10 bar above ambient pressure. So if ambient pressure is 10 bar, intermediate pressure is 20 bar.

Or you can think of it as absolute pressure vs relative pressure. The above is absolute pressure. If you're talking relative pressure, intermediate pressure is 10 bar (relative to the environment) and pressure in the second stage would be zero bar.

And I don't see why you couldn't use a 300 bar reg on a 200/230 bar tank. It's the other way around that doesn't work (because it doesn't fit).

 

[pasley]

...
Why not just have a hose like on a blending system without a 1st stage and deliver gas at high pressure to a second stage and let that change the pressure to ambient pressure and breathe that from a scuba tank. meaning no first stage?...

you could do that but you would not like it. Consider this:
1. How stiff is the high pressure hose when pressurized?
2. All the parts of the 1st stage are there to do the job of reducing the pressure. Those parts are necessary or they would not be there. If there is no first stage on the tank, all those heavy brass parts would have to be in the mouth piece we currently call the 2nd stage. How heavy is the 1st stage and would you really want to hold that in your mouth for an hour or more?
3. Where are you planning on putting the ports for the SPG and the BCD hose and/or drysuit hose?
The three items above are why we have a 1st stage and a 2nd stage.

 

[rhwestfall]

you could do that but you would not like it. Consider this:
1. How stiff is the high pressure hose when pressurized?

2. All the parts of the 1st stage are there to do the job of reducing the pressure. Those parts are necessary or they would not be there. If there is no first stage on the tank, all those heavy brass parts would have to be in the mouth piece we currently call the 2nd stage. How heavy is the 1st stage and would you really want to hold that in your mouth for an hour or more?

3. Where are you planning on putting the ports for the SPG and the BCD hose and/or drysuit hose?

The three items above are why we have a 1st stage and a 2nd stage.

Bulky? There is a better solution than that with little to no weight on your mouth....: Shop Online

:vintagediver:

 

[PfcAJ]

There's still a first stage, and often a second stage in those.

 

[rhwestfall]

agree, but his (pasley's) reasons/symptoms are not valid..

---------- Post added July 31st, 2014 at 03:18 PM ----------

now, if we want to discuss the physics of what these machines are accomplishing, and the result/performance impacts of eliminating one....

 

[dfx]

agree, but his (pasley's) reasons/symptoms are not valid..

Sure they are, because the OP asked about having a HP hose going to a regulator in your mouth. The only feasible way of doing it is how the double hose does it: move the entire regulator away from the mouth on to the tank. But then you run into other issues...

 

[raftingtigger]

Hi Everyone

So last night i was having one of them sleeplees nights when thourghts just roll around in your head. I was thinking about intermidiate presures and abient pressure and 1st and second stages and how they worked. I have a few questions about this:

So the job of the 1st stage is to take high pressure from the tank and deliver to the second stage at an intermidiate pressure at give or take ten bar, So if you was at 9o m where the pressure is ten bar would this still work or is there a difference of balanced or unbalnaced regs or diaphram or piston, could you clear this up?

Why not just have a hose like on a blending system without a 1st stage and deliver gas at high pressure to a second stage and let that change the pressure to ambient preeure and breathe that from a scuba tank. meaning no first stage?

Also i read that stictly speaking you can not use a three hundre bar reg on a two thirty two bar tank, why? is there an adapter? could some one clear all this up please?

thank
declan long

If you want to really know the ins and outs of why your regulators work I highly recommend "Regulator Savvy". If after that you want to work on your own regulators then get Vince Harlow's excellent book "SCUBA Regulator Maintenance and Repair".

The quick answer to your question was answered in post #2.

 

[TSandM]

I'm going to sound incredibly stupid, but I have wondered the same thing, about why this has to be done in two stages. Is weight really the only answer?

 

[PfcAJ]

Old regs used to have only 1 stage.

Apparently the breathing experience isn't as pleasant as a 2 stage reg.