BA156

[Open Ocean Diver]

Question: I have been comparing my BA156 to my G250V and noticed that the effort it takes to open the demand valve. On the 156 take around 5 psi, on the G250 almost instant, I can modulate my breathing from 0 to 5 psi. With the 156 it takes 5 psi to open and supply air, can’t really modulate anything below 5 psi after it opens. I’ve tried to tune the orifice but can’t get it any better. I use an inline adjuster.

Is this normal between the two?

thanks,

Kevin

 

[rhwestfall]

we usually talk in inches vacuum for cracking effort...

The G250v has the advantage of the venturi, and can make a difference.

 

[Open Ocean Diver]

we usually talk in inches vacuum for cracking effort...

The G250v has the advantage of the venturi, and can make a difference.

Ordered a meter for testing for cracking effort from Scubatools hasn’t arrived yet.

from the way I tested it do you thinks this a problem with 156? Any advised on what double be causing it?

The 156 has a new s-wing poppet and o-rings.

 

[rhwestfall]

levers and springs come to mind, as well as a healthy, supple diaphragm... I really haven't had too much issue getting them close to each other....

@buddhasummer
@couv
@axxel57

 

[tbone1004]

@Overweighted it is certainly not cracking at 5psi. That is about the limit of vacuum that most humans can generate. We normally consider 1" of H2O to be a reasonable cracking effort, and that is 0.04psi. Anything over 2" of water or 0.07psi or so is very uncomfortable to breathe and normally after a couple of breaths you will feel light headed and very out of breath, much like breathing through a straw.

How are you determining your 5psi number?

Are these on the same first stage, or at least at the same IP? The G250V has better venturi due to case geometry but that has no bearing on cracking effort, it just lowers the area under the curve for work of breathing. They should both be able to crack at essentially identical efforts. The inline adjusting tool is only part of it, the lever has to be set properly and not bent, the insides have to be clean and not sticking, diaphragms need to be nice and flexible etc. Lots of variables, but without knowing the actual cracking effort issues, it's hard to say definitively what the issue is.

 

[Open Ocean Diver]

Testing both regs on the same MK 10, have an IP gauge on one of the HP ports, so the 5 psi I’m reading is on the IP gauge. When it cracks I get a jump of 5 Psi, the G250 is smooth from 0 to 10 psi. Water test it will free flow at 1.5 inches. When I first took it apart I noticed the diaphragm was very sticky and grease all over the end of the poppet going into the BC. I’ve cleaned it and got whatever was causing it to be sticky removed, the diaphragm seems supple and in good condition. All this and still it takes more effort to start it to breath.

 

[tbone1004]

@Overweighted there must be a bit of translation issue. The IP gauge should be on one of the LP ports instead of the IP port and be somewhere around 135psi and it should drop not raise. The IP change when breathing is pretty irrelevant and not something you should worry about. As long as it is stable that is what matters.
1.5" is a bit high for those regs, but not unreasonable. IIRC the specification is 1.0-1.4 inches of water.

 

[Open Ocean Diver]

@Overweighted there must be a bit of translation issue. The IP gauge should be on one of the LP ports instead of the IP port and be somewhere around 135psi and it should drop not raise. The IP change when breathing is pretty irrelevant and not something you should worry about. As long as it is stable that is what matters.
1.5" is a bit high for those regs, but not unreasonable. IIRC the specification is 1.0-1.4 inches of water.

Sorry yes LP port and it does drop, but takes me sucking harder on the 156 before it starts suppling air. Tank has 2400 psi, IP pressure is 125. The 250 is very linear from 125 to wherever it drops and you stop inhaling, on the order hand the 156 profile is not so linear at the start from 125 jumps to 120 before it open then becomes I little more linear. I hope I’ve explained what I’m seeing a little better.

 

[Kupu]

My first thought would be checking the spring that came with the 156, if it was older and not switched along with the poppet then it could be part of the problem. If you don't have a new spring on hand, try taking the spring from the G250V and testing it in the 156.

Same thought about switching out the entire poppet assembly, but I would do the spring first and see if that helps. This because trying to avoid creating overlapping grooves on the poppet low pressure seat by using it in two different regulators, although a quick one time switch should not be much of an issue I would try to avoid it. These are times when it is nice to have a few extra new and used low pressure seats on hand.

 

[Open Ocean Diver]

I have a 108 HP apart, It has the same spring part number so I’ll try that spring first like you suggested. Thanks