Adjusting the flow of the Dolphin first stage

Flup · 5th March 2007, 12:30

Hi List,

One of my dolphin first stages has (in my opinion) a to high MP set. When i installed it the bypass wil start flowing at the moment i opened the cilindervalve. Tried another orfice, same sitution, tried another first stage, problem solved.

My qeustion is it possible to 'callibrate' the first stage, and if so, how do i do it.

Many thanks for the replies ahead.

Flup

Divein · 5th March 2007, 12:43

Can't answer the question about adjusting the first stage but have you considered adjusting your bypass valve. There is a rubber seat inside that the poppet presses against. When it gets worn air bleeds through when the cylinder valve is turned on. You can try adjusting it removing the blanking plug at the end and either tightening or loosening the nut on the end of the spindle. Loosening the nut has the result of increasing the pressure on the seat (spring relaxing) and reducing the tendency for air to bleed through when the valve is on. Hope this was of some help or maybe just confused the problem!!

**Freef** · 5th March 2007, 15:46

The first thing to try is to check the IP [interstage pressure] of the first stage, it should be 16.5 bar or thereabouts.

A leaking O ring or damaged seat are usually the causes of the problem you describe.

gibbogeo · 5th March 2007, 19:24

Quote: (Originally Posted by Flup)

Tried another orfice, same sitution, tried another first stage, problem solved.

Did you checked with the flowmeter the flow?

Flup · 6th March 2007, 07:51

Quote: (Originally Posted by Freef)

The first thing to try is to check the IP [interstage pressure] of the first stage, it should be 16.5 bar or thereabouts.

A leaking O ring or damaged seat are usually the causes of the problem you describe.

Geuss i'll have to dis-assemble the thing and give it a little service. Thnx for the reply

Flup · 6th March 2007, 07:52

Quote: (Originally Posted by gibbogeo)

Did you checked with the flowmeter the flow?

Flow of the jet's are fine, checked it on the second first stage, so there's no problem. The problem is clearly the first stage, not the orfice and/or any jets

5th March 2007, 12:30	#1 (permalink)
Flup Custom Title Allowed! Current Rebreather/s: Megalodon Dolphin Home Build Other Rebreather/s: Inspiration Vision Ouroboros Dolphin Home Build Join Date: Apr 2006 Location: Netherlands Posts: 134	Adjusting the flow of the Dolphin first stage Hi List, One of my dolphin first stages has (in my opinion) a to high MP set. When i installed it the bypass wil start flowing at the moment i opened the cilindervalve. Tried another orfice, same sitution, tried another first stage, problem solved. My qeustion is it possible to 'callibrate' the first stage, and if so, how do i do it. Many thanks for the replies ahead. Flup __________________ They say i'm all mixed up, maybe that's why i like mixed gas diving !!!! Last edited by Flup : 5th March 2007 at 15:27.
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5th March 2007, 12:43	#2 (permalink)
Divein Custom Title Allowed! Current Rebreather/s: Dolphin Home Build Other Rebreather/s: Dolphin Home Build Join Date: Jun 2006 Location: Yorkshire Posts: 104	Re: Adjusting the flow of the Dolphin first stage Can't answer the question about adjusting the first stage but have you considered adjusting your bypass valve. There is a rubber seat inside that the poppet presses against. When it gets worn air bleeds through when the cylinder valve is turned on. You can try adjusting it removing the blanking plug at the end and either tightening or loosening the nut on the end of the spindle. Loosening the nut has the result of increasing the pressure on the seat (spring relaxing) and reducing the tendency for air to bleed through when the valve is on. Hope this was of some help or maybe just confused the problem!!
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5th March 2007, 15:46	#3 (permalink)
Freef Custom Title Disallowed! Current Rebreather/s: Dolphin Other Rebreather/s: Dolphin Join Date: Jan 2006 Location: Land of the Freef, UK. Posts: 1,353	Re: Adjusting the flow of the Dolphin first stage The first thing to try is to check the IP [interstage pressure] of the first stage, it should be 16.5 bar or thereabouts. A leaking O ring or damaged seat are usually the causes of the problem you describe. __________________ David. Currently owner of two differently sized ankles.
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5th March 2007, 19:24	#4 (permalink)
gibbogeo Gilberto Bonaga, Italy Current Rebreather/s: Classic Kiss Dolphin Home Build Other Rebreather/s: Dolphin Home Build Join Date: Sep 2005 Location: italy Posts: 315	Re: Adjusting the flow of the Dolphin first stage Quote: (Originally Posted by Flup) Tried another orfice, same sitution, tried another first stage, problem solved. Did you checked with the flowmeter the flow?
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6th March 2007, 07:51	#5 (permalink)
Flup Custom Title Allowed! Current Rebreather/s: Megalodon Dolphin Home Build Other Rebreather/s: Inspiration Vision Ouroboros Dolphin Home Build Join Date: Apr 2006 Location: Netherlands Posts: 134	Re: Adjusting the flow of the Dolphin first stage Quote: (Originally Posted by Freef) The first thing to try is to check the IP [interstage pressure] of the first stage, it should be 16.5 bar or thereabouts. A leaking O ring or damaged seat are usually the causes of the problem you describe. Geuss i'll have to dis-assemble the thing and give it a little service. Thnx for the reply __________________ They say i'm all mixed up, maybe that's why i like mixed gas diving !!!!
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6th March 2007, 07:52	#6 (permalink)
Flup Custom Title Allowed! Current Rebreather/s: Megalodon Dolphin Home Build Other Rebreather/s: Inspiration Vision Ouroboros Dolphin Home Build Join Date: Apr 2006 Location: Netherlands Posts: 134	Re: Adjusting the flow of the Dolphin first stage Quote: (Originally Posted by gibbogeo) Did you checked with the flowmeter the flow? Flow of the jet's are fine, checked it on the second first stage, so there's no problem. The problem is clearly the first stage, not the orfice and/or any jets __________________ They say i'm all mixed up, maybe that's why i like mixed gas diving !!!!
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