Apeks 1st stage diaphragm clamp leaks

[rsingler]

I apologize for resurrecting the thread. Rob would not MK17 be a good alternative to XStream on an RB?

Maybe. But you'd have to get IP data from Scubapro that I've never seen. Here's the thing: absolute IP has to rise completely evenly with depth to maintain the relative IP that drives your second stage, or in the the case of an eCCR, your solenoid. It can't be "overbalanced" - a design flaw of environmental sealing that Aqualung and others falsely claim as an advantage.

Since the CCR is designed to operate at great depth, any overbalancing will have larger and larger effects on the ability of the tiny battery powered solenoid to open against IP. That is why the oxygen first stage on my CCR is set down around 105 psi, rather than the usual 135, to make it easier for the solenoid to operate without consuming the battery.

The Mk17 is sealed, unlike the Poseidon. I don't know what happens to relative IP at depth. A Mk11 might be a better alternative, if you want Scubapro. The Poseidon doesn't need sealing, because the rolling kevlar impregnated diaphragm sheds ice so well, and the wide open top rinses easily after a dive.

But as you may have gathered above, what really attracts me to the XStream is the HP seat design.

 

[elan]

Maybe. But you'd have to get IP data from Scubapro that I've never seen. Here's the thing: absolute IP has to rise completely evenly with depth to maintain the relative IP that drives your second stage, or in the the case of an eCCR, your solenoid. It can't be "overbalanced" - a design flaw of environmental sealing that Aqualung and others falsely claim as an advantage.

Since the CCR is designed to operate at great depth, any overbalancing will have larger and larger effects on the ability of the tiny battery powered solenoid to open against IP. That is why the oxygen first stage on my CCR is set down around 105 psi, rather than the usual 135, to make it easier for the solenoid to operate without consuming the battery.

The Mk17 is sealed, unlike the Poseidon. I don't know what happens to relative IP at depth. A Mk11 might be a better alternative, if you want Scubapro. The Poseidon doesn't need sealing, because the rolling kevlar impregnated diaphragm sheds ice so well, and the wide open top rinses easily after a dive.

But as you may have gathered above, what really attracts me to the XStream is the HP seat design.

Thanks a lot, this is definitely helpful. I am currently building my mosaic of knowledge about RBs.

 

[taimen]

I apologize for resurrecting the thread. Rob would not MK17 be a good alternative to XStream on an RB?

In real life, yes it is. Some unofficial 3rd party tests show that Mk17 doesn't overcompensate and behaves well down to quite extreme pressures. The Halcyon branded Mk17 version is a popular oxygen 1st stage in some GUE-JJCCR circles and seems to perform well in deep expedition diving.
Design wise I also like the XStream now. That said, the US4 does it's job. IRL it performs very well in JJ-CCRs even in very harsh environments.

 

[elan]

In real life, yes it is. Some unofficial 3rd party tests show that Mk17 doesn't overcompensate and behaves well down to quite extreme pressures. The Halcyon branded Mk17 version is a popular oxygen 1st stage in some GUE-JJCCR circles and seems to perform well in deep expedition diving.
Design wise I also like the XStream now. That said, the US4 does it's job. IRL it performs very well in JJ-CCRs even in very harsh environments.

Thank you taimen. I like SP 17/11 specifically because of the ability to torque the diaphragm. A have Apekses and Zeagles as well and the “no idea how well the diaphragm is torqued” does not give me a warm feeling. Have to trust the tolerance. And it’s probably ok but being able to measure such an important value is always good. I have completely transitioned to MK17 (except one Tek 3 Apeks set) for that reason

 

[rjack321]

All I can say is when I get them from the factory and I disassemble them to check them, the torque is TAF

Tight As F***

View attachment 658721

The screws need dressing smooth

Where does this pin spanner come from? I want one, this is the best design I've ever seen.

 

[rsingler]

Scuba-Clinic-tools.com

 

[Couv]

I'm butting in again with an observation and a question for you diaphragm first stage regulator gurus.

Looking through several Apeks first stage diagrams, I don't see a thrust washer between the diaphragm and the diaphragm cap. I was given to understand a thrust washer prevents direct contact of the two parts and helps to prevent bowing of the diaphragm due to friction. It also divides the pressure uniformly around the perimeter of the diaphragm.

Could this/these (bowing or uneven pressure) be contributing factors to the bubbling that the OP is writing about?

Cheers,

Couv

 

[elan]

I'm butting in again with an observation and a question for you diaphragm first stage regulator gurus.

Looking through several Apeks first stage diagrams, I don't see a thrust washer between the diaphragm and the diaphragm cap. I was given to understand a thrust washer prevents direct contact of the two parts and helps to prevent bowing of the diaphragm due to friction. It also divides the pressure uniformly around the perimeter of the diaphragm.

Could this/these (bowing or uneven pressure) be contributing factors to the bubbling that the OP is writing about?

Cheers,

Couv

I am no expert but I think this is done on purpose as the are specifically relying on the friction and also the grooves that run along the edge of the clamping part to hold the diagram in place. It's also metal to metal clamping pretty much till you bottom out. My understanding is that the diaphragms are designed to slip against the clamping body to an extent.

This is why I prefer SP which allows to measure the torque.

 

[Still Kicking]

I'm butting in again with an observation and a question for you diaphragm first stage regulator gurus.

Looking through several Apeks first stage diagrams, I don't see a thrust washer between the diaphragm and the diaphragm cap. I was given to understand a thrust washer prevents direct contact of the two parts and helps to prevent bowing of the diaphragm due to friction. It also divides the pressure uniformly around the perimeter of the diaphragm.

Could this/these (bowing or uneven pressure) be contributing factors to the bubbling that the OP is writing about?

Cheers,

Couv

Older US Divers regs (Conshelf etc) have a thrust washer. The current generation Aqualung and Apeks don't. Not sure about the engineering rationale but Conshelfs had a flat sealing face and, as elan points out, Apeks have a groove.

I wonder if issues of diaphragm coming unsealed could have something to do with people removing the environmental cap to adjust IP. If you don't support the clamping ring with a second pin spanner, you might loosen the clamping ring fractionally when you unscrew the environmental cap. Sometimes the cap and the ring come loose together. Just a thought.