Setting intermediate pressure on 1st stages

**Alastair** · January 16th, 2006, 07:35 PM

Hi All,

I was chatting to Mark this weekend and he's got some new tools which allow him to set the INP on the first stage. He offered to tweak my regs and altered my argon 1st stage INP down to 100 psi. What does everyone perceive as the benefits? What do people set their regs to?

Thanks
Al

NickB · January 16th, 2006, 07:51 PM

I've detuned my breathing gas regs (DS4/DST) to around 8.5 Bar and my US4 argon first stage to 5 Bar (I don't want the dry suit gas hammering in there at a huge rate of knots)

diver-repairs · January 16th, 2006, 09:25 PM

The lower the IP setting the easier the life of the poppet/ the longer it should last:thats the positive side.

However, as mentioned earlier in a different thread, the lower the IP the less air will flow down the pipe or where ever per unit time:ie longer time to pump in a set volume of gas. This may or may not give you a problem:- suit inflation should be OK at 4 or 5 bar provided that its depth compensated.
Ditto for the wing (per say), as you already have Seatech/Sitec fittings on the hose to slow down the flow relative to the Apeks/poseidon type fittings,
I'd tend to keep the Primary and Secondary regs to a minimum of 8 bar in case you want a real good glup of air at depth, so this then means that the wing has to be 8 bar aswell.

Just specify what pressure you want when you have your reg serviced or O2 cleaned and a sympathetic technician should do the rest.......

BrianC

***Bob Cooper*** · January 16th, 2006, 10:08 PM

Just to expand on what Brian has said..........

In Europe, regulators need to comply with certain requirements (I won't bore you with the details). One of these requirements is that they can supply air (yes, air) at a depth of 50m with a predetmined effort.

Now, we don't use air at that depth, we add helium, so the gas we are breathing is less dense and therefore easier to breathe. This allows us to de-tune our first stages to give the 2nd stage an easier time. We don't need a massive IP to deliver air at 50m with no effort.

To answer the question, I set my backgas regs to about 8 bar and the argon to 7 bar.

January 16th, 2006, 07:35 PM	#1 (permalink)
Alastair(Offline) DIRX Supporter Join Date: Nov 2005 Location: UK Posts: 693	Setting intermediate pressure on 1st stages Hi All, I was chatting to Mark this weekend and he's got some new tools which allow him to set the INP on the first stage. He offered to tweak my regs and altered my argon 1st stage INP down to 100 psi. What does everyone perceive as the benefits? What do people set their regs to? Thanks Al __________________ Helium is our friend - GI3

January 16th, 2006, 09:25 PM	#3 (permalink)
diver-repairs(Offline) New Member Join Date: Dec 2005 Location: North Yorkshire Posts: 34	IP settings The lower the IP setting the easier the life of the poppet/ the longer it should last:thats the positive side. However, as mentioned earlier in a different thread, the lower the IP the less air will flow down the pipe or where ever per unit time:ie longer time to pump in a set volume of gas. This may or may not give you a problem:- suit inflation should be OK at 4 or 5 bar provided that its depth compensated. Ditto for the wing (per say), as you already have Seatech/Sitec fittings on the hose to slow down the flow relative to the Apeks/poseidon type fittings, I'd tend to keep the Primary and Secondary regs to a minimum of 8 bar in case you want a real good glup of air at depth, so this then means that the wing has to be 8 bar aswell. Just specify what pressure you want when you have your reg serviced or O2 cleaned and a sympathetic technician should do the rest....... BrianC

January 16th, 2006, 07:51 PM	#2 (permalink)
NickB(Offline) Always lowering the tone Join Date: Dec 2005 Location: Cardiff, UK Posts: 344	I've detuned my breathing gas regs (DS4/DST) to around 8.5 Bar and my US4 argon first stage to 5 Bar (I don't want the dry suit gas hammering in there at a huge rate of knots)

January 16th, 2006, 10:08 PM	#4 (permalink)
*Bob Cooper*(Offline) Moderator - "Don't stop me now!" Join Date: Nov 2005 Location: South East London, UK Posts: 684	Just to expand on what Brian has said.......... In Europe, regulators need to comply with certain requirements (I won't bore you with the details). One of these requirements is that they can supply air (yes, air) at a depth of 50m with a predetmined effort. Now, we don't use air at that depth, we add helium, so the gas we are breathing is less dense and therefore easier to breathe. This allows us to de-tune our first stages to give the 2nd stage an easier time. We don't need a massive IP to deliver air at 50m with no effort. To answer the question, I set my backgas regs to about 8 bar and the argon to 7 bar.