USD Micra/Cousteau wet breathing

[=C=]

Afternoon all,

I would ask what should be considered as a culprit for a wet breathing micra adjustable on a 2m hose attached to a Cousteau SEA 1st stage. My regs came back from service after a prolonged interval and returned breathing ''funny". My aquarius/calypso combo came back with a hissing sound (fixed whith the manual a SBer directed me to) however; the micra delivers no where near the volume of air it once delivered.

Adjusting it to maximum gives comfortable air for shallower depths and around 30m it becomes an uncomfortable wet gargle. I believe this is a 1st stage issue and am a bit weary about cracking it open. I'm searching for service tools/manuals now and would like to handle this issue and future service by myself. Whats a good source for this stuff?

Thanks for any advice,
C

 

[Couv]

Hello Tartullian,

While you can not entirely rule out the first stage for poor performance, it is probably not the cause. I am not very familiar with that regulator, but generally speaking a wet breathing regulator (that was previously dry) has the following suspects. 1: the exhaust diaphragm is wrinkled, has something under it or is the wrong size or something similar. Pull off the exhaust cover and have a look, this is usually an easy fix. 2: the main diaphragm is not seated correctly, is torn or has a hole in it. Below, I will add my usual regulator check post. Find info regarding a water tight check, but while you are there, do the rest of the checks that you have tools and time for.

I am a bit suspicious about the last service visit it had. I hate to ask, but is the repair facility one that you trust? If it has been recent, tell them you are not happy with it especially if it still under warrantee. If you are sure you want to come to the Dark Side and will service your own regulators...read on.

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

Regulator inspection:

There are a few checks that everyone is capable of doing. One is the intermediate pressure check. Get a simple 300 psi pressure gage from Ace Hardware (I like the helpful hardware man better that the giant store types) and adapt it to your quick disconnect
SCUBA Hoses and Adapters..Variety of Lengths, Colors, Fittings
or get a pre made one : Intermediate Pressure Gauge Plugs Into The BCD Quick Disconnect Hose from LeisurePro.com

Find out the what the IP range should be for your regulator (most are ~ 135 +/- 10 psi .)

The intermediate pressure should remain steady after stabilizing within the acceptable range. If it tends to climb (creep) that indicates there is a problem with the first stage that must be corrected.

Another check is the cracking pressure of each second stage. Partially fill your kitchen sink and immerse the regulator with the mouth piece up. Air should begin to flow before the diaphragm gets more than a 1 1/2 of inches deep. You may have to put plastic tubing in place of the mouth
piece to do this, but usually not. If you want to get fancy (there is no reason to get fancy) make a simple manometer from plastic tubing and a yard stick * » * » Manometer
and you can check the cracking pressure with a good deal of accuracy. If you want to get REAL fancy, buy a Magnehelic gage from eBay, but again no reason to do that.

Next, a water tight check is also very easy to perform and checks the integrity of the second stage housing. Hook
the first stage up to a tank and without turning on the air (or if you have a good tight dust cap you can use that instead) draw a breath on the second stage until you hear the diaphragm retract. Do not draw too hard as it will collapse the exhaust valves and cause a leak. Does the regulator hold
vacuum? If so, it is probably water tight.

These simple checks can be done by anyone. They should be done often, not to mention when new out of the box or after shop service.

Check early, check often.

couv

 

[Hallmac]

There is a common issue I have not observed being posted with the Micra adjustable that can cause a leak or wet breathing. If it was assembled in the wrong order it is common for the plastic nut under the adjustment knob to crack.

I am sure as you have read here this is not a favorite second stage to service from the majority of techs out there. There are a few procedures that if you do out of order will create a long day on the bench.

If you looked at the exhaust valves and they appear to be sealing OK, I would look for one of two things.

First gently drive the roll pin out of the adjustment knob and pull the knob off. Check the plastic nut to see if it is cracked.

Second thing would be the diaphragm is not seated properly.

Remember these are above the typical reasons for leaks like torn mouth piece, bad o-rings, debris, etc.

I could probably share a diagram of the Micra if you find it necessary.

 

[The Chairman]

It is actually common for the housing to crack and cause this to happen. I love the Cousteau, but abhor the Micra for this reason.

 

[=C=]

Great posts! Thanks gents.

I am a bit suspicious about the last service visit it had. I hate to ask, but is the repair facility one that you trust? If it has been recent, tell them you are not happy with it especially if it still under warrantee. If you are sure you want to come to the Dark Side and will service your own regulators...read on.
​

I am extremely unhappy with the service (1st service in Czech)... Thats why the regs arent going back there. They are the only AL/USD agent in the country.​

 

[tfsails]

When I service a second stage, any second stage, I assemble it, plug up the inlet fitting with my finger, and inhale on the stage. If it is assembled properly it will maintain vacuum. I have discovered many a cracked housing/misplaced o-ring/dumbass mistake by me by doing just that. Only after I've verified the airtightness of the stage do I put it on the bench and check it for cracking pressure, etc.

Don't inhale too hard; you can do damage to exhaust valves or diaphragms that way, but you can inhale fairly forcefully.

A Micra second stage, properly adjusted, will deliver a LOT of air, providing the first stage is properly adjusted. If you have low airflow, get the reg re-serviced by someone you trust. That's your life when you're underwater.