YD Scuba Diving Forums banner
1 - 10 of 10 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter · #1 ·
Hi!

I've tried emailing Apeks about this, but never got a reply.

Anyway - The Apeks "dry-sealed" first stages apparently have an overbalancing feature that actually doesn't provide a constant intermediate pressure (above ambient), but increases more than the ambient pressure when descending.

Does anyone know exactly how this works, when (at which depth) does the intermediate pressure rise above what has been set, and is this a linear increase?

Question is in regard to using an Apeks dry-sealed first stage to provide oxygen to a solenoid on an eCCR.

Thanks :)
 

·
Keyboard Worrier
Joined
·
4,154 Posts
It doesn't rise higher than, it just rises faster - as I read their blurb:
ie faster rise in pressure so you never below the pressure you need.


OVER-BALANCED DIAPHRAGM DESIGN
The heart of any regulator is the first stage. Most Apeks first stages utilize a unique Over-Balanced diaphragm design. In an over-balanced first stage design, the interstage pressure in the hose increases faster than traditional balanced models as a diver descends to greater depths. This increased interstage pressure compensates for the increased density of your breathing gas by allowing a larger volume of gas to flow through the system on demand. The result is superior breathing performance regardless of depth. The Over-balanced Diaphragm Design is found on Apeks Tungsten, XTX200, XTX100, XTX50, XTX40 and XTX50/DS4 first stages
 

·
Registered
Joined
·
4,259 Posts
The air space in the sealed end of the DST causes an increase in IP with depth. Remove the sealed end and replace it with the unsealed cap to remove this issue.

Matt.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #7 ·
The air space in the sealed end of the DST causes an increase in IP with depth. Remove the sealed end and replace it with the unsealed cap to remove this issue.
This would also remove (at least in part) Apeks' freezing-protection, which is provided by the dryseal. Although probably being a minor issue with the limited gasflow in a first stage used solely for feeding a solenoid, it's worth mentioning. I'm not sure wether the surface of the interiors are the same in a sealed vs unsealed first stage, with regard to its suitability for suddenly being in a salt water environment if ment for a drysealed environment.
 

·
Registered
Joined
·
4,259 Posts
I'm not sure wether the surface of the interiors are the same in a sealed vs unsealed first stage, with regard to its suitability for suddenly being in a salt water environment if ment for a drysealed environment.
The parts are the same; the spreader, spring and diaphragm get wet, only the end cap is different, as is the IP adjustment nut.

Matt.
 

·
So raise your hand if you think that was a Russian
Joined
·
11,158 Posts
This would also remove (at least in part) Apeks' freezing-protection, which is provided by the dryseal. Although probably being a minor issue with the limited gasflow in a first stage used solely for feeding a solenoid, it's worth mentioning. I'm not sure wether the surface of the interiors are the same in a sealed vs unsealed first stage, with regard to its suitability for suddenly being in a salt water environment if ment for a drysealed environment.
Article said:
Environmental seals keep water from circulating within the first stage, and this actually lowers the first stage temperature, thereby encouraging icing and possible free flow. As technical divers dive deeper and deeper it is important to know another highly undesirable feature of some environmental sealed first stages.
Although here he seems to allude to the fact that the antifreezing mechanism could cause freezing, his theory (AIUI) is that the ambient water, being liquid, is warmer than it's freezing point and would therefore warm up the 1st stage and prevent it icing up.

The flaw in his argument, as far as I can see, is that an environmentally sealed reg has no water around the moving parts to freeze, as long as your cylinder air is dry. Any ice formation would be external and subject to the same warming effect that he says would benefit the internals.
 

·
bulging sweaty dirty putrescent member
Joined
·
1,331 Posts
I'm not too sure that the environmental seal offers any freezing protection. it seems logical that waterflow over the metal parts of the end cap, diaphragm clamp and valve body serves this purpose.
 
1 - 10 of 10 Posts
Top