R190 air delivery and exhalation effort

[David P]

Hoosier:still have the hole pointing towards your mouth unplugged

eric:when you tested the regs, by chance was one time dry, one time in the water? If I breath very lightly, then I can feel a huge difference between having the reg above and below water. They breath much nicer under water. If you don't believe me, sit in a pool with the reg just out of water and breath nice and light, then stick you head down a few inches so the reg is just under water and repeat. You will feel a difference.

 

[Hoosier]

Do you think so? I thought so as well.

But, my experience was different on the LEFT HAND 2ND STAGE.

Based on my trial and error, there is a difference which aspirator holes is pluged.

I had chance to tune up R190 for my SM rig. R190 was newly serviced and O2 cleaned last week, but I didn't tune it up yet by last weekend.

IP on MK2 shows 137~140psi at 2600 psi in steel 72CF tank. Based on SP manual, "IP on MK2 should be 125psi-145psi at 3000psi and at 300psi supply pressure." So, it is in good condition.

After attaching pneumatic adjusting tool, I made the initial air on adjustment to stop all free flowing and de-tuned the second stage orifice. However, whenever pushing the purge button, it hissed until block the mouthpiece (very strong air out). So, I de-tuned more and more, but an inhalation range became out of boundary.

So, I deassembled everything and adjusted the locknut a little bit and changed a housing plug location, PLUG the hole toward the mouthpiece.

Bingo. It solved all problems and I can breath it very well even in 40 degree water without any free flow issue.

One cons is that when you push the purge button, the air flows out more to the exhaust valve than the mouthpiece.

 

[DA Aquamaster]

The idea with having the plug that point toward the mouth piece open is that the flow will be directed out the mouth piece and create a venturi affect. If you want to reduce that effect, keep the flow vane in the "min" position and it will direct the flow back, create positive pressure in the case and push the diaphragm back off the lever, closing the valve and preventing a freeflow.

Unplugging both ports is not spec but is still most likely ok as it directs at least half the air in the right direction and with the pressure reduced out both ports would not have as significant effect in terms of the exhaust valve.

Plugging the top port and leaving the bottom port open may resolve your freeflow issue, but the cost is not worth the benefit as it wil have an overall negative impact on performance.

 

[Hoosier]

I acknowledge a venturi effect and I played a VIVA control knob as well, but it didn't help that much.

So, as I mentioned, what I have done were

1. a little bit screw down a locknut. One thread is for a primary and two thread is for a octo. I think mine is 1.3 thread.
2. change a plug position

I don't know which factor was a real winner though. It works great at this moment.

Hmm~~

An overall negative impact on performance? Such as?

 

[DA Aquamaster]

At depth blowing air out the exhaust valve rather than through the mouthpiece would be the worst case.

Best case is it just redirects the air the long way around the case and makes it breath like a rock.

 

[Hoosier]

Thanks.

I will try it more at depth.

 

[ericpitar]

Hello all,

'Just an update. Today, I had my r190 adjusted by the tech and now feels smooth both in inhalation and exhalation in my pool test. I didn't feel any positive pressure breathing, but then again, I don't remember feeling that either in my first pool test before I tested it in my last open water dive.

The tech did the adjustment on the R190's receptacle where the LP hose fits in. (Don't know the proper terminology, sorry.) The first stage wasn't touched as everyone suggested it needn't be.

I'll try to provide an update after my next open water dive to see if that positive pressure breathing is still there.

One more question: Can a reg (such as this R190) provide smooth inhalation and exhalation without the feeling of positive pressure breathing?


E

 

[halocline]

H
One more question: Can a reg (such as this R190) provide smooth inhalation and exhalation without the feeling of positive pressure breathing?


E

You're asking a subjective question. Based on my perception and experience, I would say yes. But, it's not going to breathe like a G250 or D400. The D400 (well, D300 in my case) in particular has a very smooth quality to the airflow. As DA was describing in an earlier post, over the years entry level regs have relied more on venturi assist for airflow. This will make the reg feel a little less natural IMO, but it does put more air in your mouth, which I suspect makes a lot of (especially new) divers feel a little more secure. I personally have no hesitation about using my R190 and find it way better than other downstream unbalanced 2nds I've used.

When you get your 109 and get it serviced, you'll probably understand exactly what I'm describing, as the metal case regs have very little venturi assist and a nice smooth flow. Just to fend off a likely concern when you start using it, make sure you have a mouthpiece you are very comfortable with and the most comfortable hose length for it. Those old metal case regs are heavy; with the right mouthpiece and hose configuration they're comfy, but without they can feel a little clunky in your mouth.

I have three friends that I introduced the SP metal case regs to. One didn't like it because she felt the reg was falling out her mouth all the time. One loved it but was stunned by how easily air flowed and ended up doing most of the dive with the resistance knob turned in several turns. (he was used to the genesis 2000, if that gives you an idea about the difference) The third was an instructor who immediately wanted to buy it from me, after having demo'ed lots of regs from various manufacturers.

 

[Couv]

Hello all,

'Just an update. Today, I had my r190 adjusted by the tech and now feels smooth both in inhalation and exhalation in my pool test. I didn't feel any positive pressure breathing, but then again, I don't remember feeling that either in my first pool test before I tested it in my last open water dive.

The tech did the adjustment on the R190's receptacle where the LP hose fits in. (Don't know the proper terminology, sorry.) The first stage wasn't touched as everyone suggested it needn't be.



I'll try to provide an update after my next open water dive to see if that positive pressure breathing is still there.

One more question: Can a reg (such as this R190) provide smooth inhalation and exhalation without the feeling of positive pressure breathing?


E

The adjustment the tech made is the orifice adjustment. Basically it brings the mating surfaces (hard seat and soft seat) in contact with each other. In order to stop the flow of gas (intermediate pressure) into the second stage body the orifice (hard seat) must contact the poppet seat (soft seat) with enough force to stop the flow. Just like the seats in your sink plumbing. Now, the trick here is to adjust the orifice to just at the point where it shuts off the gas flow. Next, the lever height is set to the proper position so that the diaphragm will smoothly operate the lever which in turn moves the poppet away from and toward the orifice.

All this sounds simple enough, but why then the problems? One thing is the insidious plan that all soft seat have to take a set. Being rubber, after it has been under force for a while, a groove will form. This groove should actually serve to help seal off the gas flow, but because the groove actually slightly separates the hard and soft seat a slight free flow can occur. There are a few techniques to combat this, but suffice to say it takes time for the groove to form and consequently the regulator may need a final adjustment.

This puts the shop tech at a disadvantage over the DIY guy. He has to go through the procedure of "breaking in" the regulator and do his best to tune it for minimal cracking pressure and pray that after several dives a free flow will not develop. One trick some shop tech use is to set the cracking pressure higher, which may work, but increases the inhalation resistance.

Now there are several other factors involved in the air flow and smooth operation of the second stage, but for the most part proper adjustment and break in are key.

I look forward to your report on your 190, but when you get that real regulator (109) in the mail and overhauled, life will be grand and we can continue from there.

couv

Edit, well at least Mattboy and I did not step too hard on each other.....those guitar players have fast typing fingers.

 

[ericpitar]

Just got back from a dive trip. The R190 performed flawlessly. No positive air pressure feel in the breathing. I compared it with my R295 which performed fine but the latter seemed a little bit noisier, but felt fine really. My lungs didn't get sore as I used to feel after a few dives using rental equipment ( I think the rental I used in the past was MK2/R190).

I tried several times to go vertical and look up to see how much the breathing resistance increased. It did increase but not as much as when I used rental equipment as far as I remember.

It makes me wonder how much more performance a G250 or R109 will provide.... I'll find out when I get this R109 serviced/overhauled.

Just to fend off a likely concern when you start using it, make sure you have a mouthpiece you are very comfortable with and the most comfortable hose length for it. Those old metal case regs are heavy; with the right mouthpiece and hose configuration they're comfy, but without they can feel a little clunky in your mouth.

So, what is the proper hose length for the primary? Is this a matter of trial and error? Are there guidelines or hints?

Thanks again!

E