R190 air delivery and exhalation effort

[redacted]

What exactly do I tell the technician? "Please adjust for minimum inhalation effort of 1.2" of water"?

Can someone describe how he would do this? I don't want him telling me he "did it" by turning a little screw if there's something else involved in doing this.

You should just tell your tech that it is noticeably harder breathing than your R295 and is not comfortable. He should be able to take care of the rest. The difference between an IP of 140 vs. 145 should be unnoticeable to the diver unless the higher IP results in a freeflow. Once the IP is set withing spec (and 140 - 145 is probably a good setting for a Mk2 1st at 3000 psi) the rest of the adjusting should be done at the 2nd stage.

But not of this will address the exhaling resistance so tell him about that also.

 

[halocline]

Additional info......The tech changed the IP from 145 to 140. Also, this R190 is actually an octo and now that you mentioned about the "plug", I recall somebody (perhaps DA Aqua) mentioning a difference in the "plug(s)" between an octo and non-octo R190. Are we on to something here?

Meanwhile, the R295 that was my primary-turned-octo no breathes better than the R190 so I might actually promote the R295 back to its primary 2nd stage status.

Maybe the increase in inhalation resistance was due to the lower IP. My guess, and this is just a guess, is that when you told the tech there was "too much air" he lowered the IP and left it at that. I think you said this is a MK25, right? Then 140 is a better IP than 145 anyway. It's still a little on the high side; within specs, but since IP will tend to rise as the seat wears, it's probably best to set it at 125-130 at service. Believe me, the MK25 puts out PLENTY of air at the lower IP. The tech is going to want to leave it at 140 and I don't blame him. He could back off on the R190 orifice a little to match the new IP, if it makes any difference. If he really only changed it 5 PSI, I doubt you'd notice much of a difference.

Anyhow, since you can't seem to get the R190 the way you want it, why don't you either buy a new G250V or get a good condition used G250 or D400. Once those are serviced, you'll be getting the most out of your high end 1st stage. You can use one of the unbalanced 2nds as your octo, pick up a MK2 used sometime to match the other unbalanced 2nd, and have a complete back up reg.

 

[ericpitar]

DA Aquamaster said: "If the lever is properly adjusted, the reg should begin delivering air with only a slight depression of the purge button. If it requires more depression than normal to get the reg to purge, it should be taken in to be readjusted."

Question for DA: What is "slight"? How many millimeters depression is this?

 

[ericpitar]

Guys,.....thank you thank you thank you!!!!! Awesome group here...

Can anyone recommend a reference, a book but preferrably online to give me more background on the parts that have been mentioned? Maybe a blueprint/servicing illustration of an R190 or G250 or any other 2nd stage that would give me a better picture of what the tech is tinkering?

 

[ericpitar]

Mattboy, I'm waiting for my r109. I should have it in a couple of weeks.

e

 

[Couv]

Guys,.....thank you thank you thank you!!!!! Awesome group here...

Can anyone recommend a reference, a book but preferrably online to give me more background on the parts that have been mentioned? Maybe a blueprint/servicing illustration of an R190 or G250 or any other 2nd stage that would give me a better picture of what the tech is tinkering?

Eric,

Welcome to the DIY club. Both service manuals usually discussed here are great, Vance Harlow's "SCUBA Regulator Maintenance …." http://www.airspeedpress.com/newregbook.html and the Peterbuilt Book, "Regulator Savvy" http://www.scubatools.com/ (currently not open for business but should return soon) are well worth the money. I have both and recommend getting one of each. If you are dead set on getting only one, then Vance's is a little more suitable for the DIY guy. Peterbuilt has some pretty decent tools too, so if you order from there, pay a few extra bucks and get the bullets, spanners, etc that you need the first time and save on shipping. After just one or two seasons of servicing your own gear, you will have recovered your investment.

Here is a website that has tons of manuals: Regulator manuals

Once you have downloaded the manuals, look for the MK20-25 repair guide; not just because it shows your 1st stage, but because there are some really good and clear instructions and pictures there to help you better understand piston 1st stages in general.
In that packet, you will also find loads of info on second stages including your 190. For info on your incoming 109, the closest thing will be the G250. Again, there are clear pictures and instructions given in G250 HP repair guide.

c

 

[tfsails]

DA Aquamaster is spot on in the above post. Adjusting a second stage (from any manufacturer)with a nut on the poppet keeping the demand lever on is a balancing act between the orifice and the poppet nut. You have to adjust the orifice for no leak and the poppet nut for no play between the demand lever and the poppet. If done right, and if the spring is ok, you will come out with the proper cracking pressure. Shake your second stage while it's pressurized; if you hear a rattle, the poppet nut is too tight and the purge button won't open the poppet fully. Be sure to shake it fore and aft and not up and down, else you won't hear any rattles at all.

I've seen lots of second stages that require a hard exhalation effort on the first breath if they've been sitting a while. I'm not sure why they do that because each one of them has had a good exhaust valve and nothing causing it to stick to the housing.

 

[superstar]

There are two holes in the poppet assembly and in the good old day, both were open. The plugs cam along to plug one of them to increase free flow resistance to meet EU standards. The plug normally goes in the aspirator hole that points away from the mouthpiece.

Personally, if I owned an R190, I'd take the plug out.

The VIVA flow vane works well to reduce the positive pressure effect when breathing from the reg. My thoughts are that an R190 should be adjusted for minimum inhalation effort of 1.2" of water.

I pulled the plug out of my 380's poppit assembly and I didn't notice any major difference in breathing performance. No mater what I do to the 380"s tune I just can't seem to get it to match the performance of my 108.

 

[DA Aquamaster]

I pulled the plug out of my 380's poppit assembly and I didn't notice any major difference in breathing performance. No mater what I do to the 380"s tune I just can't seem to get it to match the performance of my 108.

I work on a lot of R190/R380/R390/R290/R295 regs and the most noteable trait is the variablity within regs of the same model and family. Some R190's/R390's/R plastic whatevers offer first rate performance and others are rough and/or hard breathing no matter what you do to them.

In contrast I agree that I have never found a metal cased R108 (or R109 for that matter) that I coudl not easily make breathe well. In large part I think it is a quality and quality control issue as the metal cases are superbly made and the older parts such as metal orifices were far superior to their modern plastic counterparts.

Back in the day, it was accepted that on a balanced first stage, the R108 "High Performance" (actually Sp's entry level second stage, similar in design to the R190) could eb tuned to breathe as well as the upper end R156 "Balanced Adjustable" or the then new G250 (which is still the gold standard of technical diving second stages.)

In looking back over 25 years of diving, it is pretty apparent that second stage regulator designs have, in the interest of reducing production cost, taken a step backward at the entry level and have not really progressed substantially if at all at the high end level.

 

[Hoosier]

Based on the manual,

"The housing plug should be in the aspirator hole AWAY from the mouthpiece if the regulator is set up as a RIGHT HAND second stage."

How about a LEFT HAND second stage?