Servicing my own gear

[halocline]

For balanced (Mk25) or over-blanced (Mk11 / 17) regulators - the initial IP tuning occurs at 500psi.

Would you elaborate about the MK11/17 being "overbalanced"?

 

[tbone1004]

the mk17 per all sealed diaphragms are over-compensating. It's a design choice that has been twisted into marketing gimmicks. The IP goes up at a rate higher than the increase in pressure. Read up
deep diving regulators

and yes, I have experience IP creep on regulators that I have rebuilt shortly after servicing due to bad batches of HP seats. From Poseidon, Apeks, and Hog. It happens, not the manufacturer or the tech's fault, sometimes there is a bad HP seat, nature of the beast. It's exceedingly rare, I think I had 1 from Poseidon, 2 from Apeks, and 2 from Hog, but it happens. I know a few others friends that have had the same scenario happen to them

 

[bl6394]

Would you elaborate about the MK11/17 being "overbalanced"?

This was a term that Rene used in the service class to describe a design feature of the Mk11 and Mk17: leading to an inverse relationship between the supply pressure and IP. I've seen the term used in a few other marketing settings.

As an example, At 3000 psi, the IP of a Mk 11/17 may be 130-135 psi. As the supply pressure decreases, the IP will climb - up to a point of course. The initial tuning target for the Mk 11/17 is to adjust the IP to 145 psi with a supply at 500psi. As you increase the supply pressure from 500psi to 3000psi, you should see a decline of the IP pressure - perhaps up to 15 psi depending on the condition of the regulator components.

 

[tbone1004]

This was a term that Rene used in the service class to describe a design feature of the Mk11 and Mk17: leading to an inverse relationship between the supply pressure and IP. I've seen the term used in a few other marketing settings.

As an example, At 3000 psi, the IP of a Mk 11/17 may be 130-135 psi. As the supply pressure decreases, the IP will climb - up to a point of course. The initial tuning target for the Mk 11/17 is to adjust the IP to 145 psi with a supply at 500psi. As you increase the supply pressure from 500psi to 3000psi, you should see a decline of the IP pressure - perhaps up to 15 psi depending on the condition of the regulator components.

The MK17 should hold a more stable IP than that.... The pistons are the ones that usually see the IP creep up as the supply pressure goes down. The 17 should go up at a rate faster than the ambient pressure due to the thumb tank principal in the article linked to above.

 

[bl6394]

The MK17 should hold a more stable IP than that.... The pistons are the ones that usually see the IP creep up as the supply pressure goes down. The 17 should go up at a rate faster than the ambient pressure due to the thumb tank principal in the article linked to above.

Reviewing my notes (and tutorial videos) the following is expected. In summary:
Mk25 (piston) - initial setting of 125-145 @ 500. Expected inversion of 1-5 psi as you climb to 3000. (Make all IP adjustments with unit depressurized.)
Mk11/17 (diaphragm) - initial setting of 145 @ 500. Expected inversion of approximatly 10 psi as you climb to 3000. (Unit may be pressurized during IP adjustment.)

This is consistent with the behavior I typically see in the Mk 11, 17, and 25 regulators I service.

 

[DoubleAA]

i had to buy an ultrasonic cleaner ($150 canuck) and an ip pressure gauge (online purchase as my LDS would not sell me one - idiots) and i scrounged a fine thread bolt from a local industrial supplier for my first stage mounting tool. no other specialty tools required.

i have old school sherwood regs so i grabbed a handfull of service kits off ebay. service manual was on frogkick.

i once ended up buying a complete used reg set on ebay inorder to get a replacement piston as my LDS screwed up one of our regs (this is what caused me to service my own gear).

so far i am not dead. our gear works just fine. i rent a tank once a year from my LDS when i check the regs...

If my local dive shop refused to sell me an IP gauge I would find another shop. I keep an IP gauge in my extended save a dive kit that goes in the truck with the rest of my gear when going on a trip.

 

[bl6394]

If my local dive shop refused to sell me an IP gauge I would find another shop. I keep an IP gauge in my extended save a dive kit that goes in the truck with the rest of my gear when going on a trip.

wow. lol. Talk about short sighted...

During my Equipment Class - the IP gauge is something I try to SELL my students. Suggesting that they can monitor the health of their of own regulators by noting changes in IP, drift, creep, etc.

smh.

 

[redacted]

The MK17 should hold a more stable IP than that.... The pistons are the ones that usually see the IP creep up as the supply pressure goes down. The 17 should go up at a rate faster than the ambient pressure due to the thumb tank principal in the article linked to above.

Piston regs usually experience some degree of IP drop as supply pressure drops.

 

[halocline]

the mk17 per all sealed diaphragms are over-compensating. It's a design choice that has been twisted into marketing gimmicks. The IP goes up at a rate higher than the increase in pressure. Read up

I'm familiar with these so called "over balanced" regulators but the MK17 is not one of them. And that's not what the other poster was referring to anyway.

 

[halocline]

This was a term that Rene used in the service class to describe a design feature of the Mk11 and Mk17: leading to an inverse relationship between the supply pressure and IP. I've seen the term used in a few other marketing settings.

This "design feature" is simply a result of diaphragm 1st stages being upstream valves. This results in IP rising as tank pressure lowers. It's been going on at least since the DA aquamaster and any other unbalanced diaphragm regulator. The issue with the MK11 and 17 is that the balance chamber does not fully compensate for this upstream bias. A diaphragm that experiences IP rise as tank pressure drops is in effect "under balanced" not "over balanced."

The marketing term "overbalanced" usually refers to 1st stages that experience greater IP increase with depth than the actual difference in ambient pressure. This is due to an oversize sealing diaphragm that transfers a larger total pressure change via a spool or piston sort of device to the inner diaphragm. I don't believe the MK17 fits that category.

But "overbalancing" has nothing to do with the MK11 or 17 IP rise through the supply pressure.