Mares Abyss Second Stage Adjustment Question

[redrover31]

Hello

Question if the setting of the adjustable orfice has changed over the series of Abyss second stages.

The manual I have mentions to turn clockwise with a 5mm hex key until it stops, then turn counterclockwise 3 turns.

I have also seen some posts mention counterclockwise 4 turns.

Is there a standardized setting for all Abyss second stages through the years, or did it vary from the early ones with the metal orfice to the later model ones with the green plastic orfice?

Any input appreciated

 

[rsingler]

Tuning for any second stage with an adjustable orifice:
1) position orifice so that
a: the valve seals at IP, and
b: when the reg is pressurized, the lever is at a height that is just beneath the diaphragm disc, with 0-1mm clearance;
2) adjust poppet spring pressure (if present) so that cracking effort is within specification.

 

[redrover31]

Thank you, the Mares Abyss I believe has a further consideration in that the orfice lies in front of a Venturi tube or VAD. Too far out it will block the tube and nullify the Venturi effect, too far in and the squared off section of the LP poppet becomes unseated from the body.

 

[rsingler]

Yes, that's been a selling point of Mares - that Venturi tube. But I believe the underlying principle still applies. And I think the three vs four turn preliminary positioning will affect valve seal and lever height more than the Venturi tube take off.
But your point is well taken!

For me, preliminary orifice position is always the point at which the valve just seals at Intermediate Pressure. Then I add an additional 30° (one twelfth of a turn, or five minutes on a clock face) of clockwise orifice turning. Then I check lever height, and only then do I worry about cracking effort.

 

[Zef]

Yes, that's been a selling point of Mares - that Venturi tube. But I believe the underlying principle still applies. And I think the three vs four turn preliminary positioning will affect valve seal and lever height more than the Venturi tube take off.
But your point is well taken!

For me, preliminary orifice position is always the point at which the valve just seals at Intermediate Pressure. Then I add an additional 30° (one twelfth of a turn, or five minutes on a clock face) of clockwise orifice turning. Then I check lever height, and only then do I worry about cracking effort.

So with reference to the Abyss 2nd stage would your method be as follows?:

1. set preliminary orifice position at point where it just seals at IP.
2. adjust lever height by tightening/loosening locknut so that lever is within 1mm from diaphram.
3. Check cracking pressure....if too high adjust orifice, then recheck/readjust lever height.
4. Check cracking pressure again as in step 3....if still too high then continue to adjust as in step 3. - repeat as necessary until proper cracking pressure is achieved.

-Z

 

[rsingler]

So with reference to the Abyss 2nd stage would your method be as follows?:

1. set preliminary orifice position at point where it just seals at IP.
2. adjust lever height by tightening/loosening locknut so that lever is within 1mm from diaphram.
3. Check cracking pressure....if too high adjust orifice, then recheck/readjust lever height.
4. Check cracking pressure again as in step 3....if still too high then continue to adjust as in step 3. - repeat as necessary until proper cracking pressure is achieved.

-Z

Correct!
With the small addition that after obtaining a seal, I add 5 minutes on the clock to accomodate the set that will accumulate in the seat. That indentation is effectively like backing out the orifice a touch, so you have to compensate.

Also, when you adjust lever height under pressure you need to be extremely careful when the lever touches the diaphragm. When you screw down the faceplate, some diaphragms are displaced slightly, which tends to open the valve. So you end up screwing in the orifice, and raising the lever, and screwing in the orifice, and raising the lever... You can chase your tail quite a bit this way.
Instead, I always leave a paper thickness of play between the lever and diaphragm, or listen for the slightest clack of lever noise when you shake a pressurized reg. That tells me that the lever is not being pressed by the diaphragm, and that the determinant of cracking effort is now solely spring tension. This tiny loss of maximum lever excursion is not enough to compromise gas delivery.

In contrast, the helpful guy at the beach who offers to fix your freeflow problem by just screwing in the orifice and, "You're done! Isn't that great?", might have just given you a dropped lever with severely compromised max flow.