SM regs: XTX50 vs Dive Rite vs ??

[tbone1004]

@stuartv that basically describes how the rest of us figured it out before instruction was available....

better than the buddy and the video though is a mirror. Doesn't have to be that big, saw one in Jocassee that was like 2x4ft ish and was enough to get all of my in there from fairly close by. If you have pool access, just lead it against the wall and you'll be good to go. Instant feedback. Nice thing with sidemount is to change a tank adjustment you can leave a screwdriver/socket driver in the pool with you if using worm clamps, or if using cam bands just adjust them as needed. Can't do bungee adjustments, but if doing it in the shallow end it's pretty easy

 

[kensuf]

"Overbalancing" is a design defect that marketing departments have tried to turn into an attribute. Theoretically, a first stage should provide a stable IP throughout both the ranges of depth and tank pressure. There should not be any change in intermediate pressure at all. If you are diving with an unbalanced second stage the increase in IP could cause it to free flow if it was tuned to the edge. This is not something you want on a deep dive. Apeks can get away with overbalancing because all their second stages are balanced which reduces the probability of free flow.

My gut feeling on this it that it is due to the way Apeks adjusts for depth. Apeks uses a mechanical link (the hydrostatic transmitter), while in the past others used some type of oil. For example, in the Conshelf Supreme, which used unbalanced second stages, Aqualung used oil to transmit depth information to the diaphragm. The oil was messy when it leaked so it was abandoned. Many regulators such as Dive Rite, Hog, Hollis, etc. are based on the Apeks design (if not an outright copy) so they are overbalanced also because they have the same defect.

Also why would overbalancing be needed? Divers who dive close to and beyond traditional recreational depth limits are going to be using some type of helium mixture which is lighter than air and has different flow characteristics.

So there's some great info in here. I've personally been bit by the "overbalanced causing a free-flow" problem at 270' and I have a friend that had a similar problem at 330'. In my case, I had an unbalanced second stage paired to a DS4 first stage and my friend was using an Apeks first stage for his O2 regulator on his CCR -- it popped his overpressure relief valve.

The IP creep is caused by the design of the dry seal system in the Apeks first stage. There's a mushroom with a plunger that seals the first stage and the way the plunger presses against the body causes an IP increase of somewhere around 2 to 4 PSI per ATM. There's some useful info here that can explain what's going on with the IP boost.

deep diving regulators

You can solve it by removing the environmental cap / mushroom.

 

[ams511]

So there's some great info in here. I've personally been bit by the "overbalanced causing a free-flow" problem at 270' and I have a friend that had a similar problem at 330'. In my case, I had an unbalanced second stage paired to a DS4 first stage and my friend was using an Apeks first stage for his O2 regulator on his CCR -- it popped his overpressure relief valve.

The IP creep is caused by the design of the dry seal system in the Apeks first stage. There's a mushroom with a plunger that seals the first stage and the way the plunger presses against the body causes an IP increase of somewhere around 2 to 4 PSI per ATM. There's some useful info here that can explain what's going on with the IP boost.

deep diving regulators

You can solve it by removing the environmental cap / mushroom.

Thanks for the link. It is ironic that removing the cap solves the problem but Apeks charges more for regulators with the cap. It is significantly cheaper to buy a US4 or UST over a DS4 or DST.

 

[tbone1004]

Thanks for the link. It is ironic that removing the cap solves the problem but Apeks charges more for regulators with the cap. It is significantly cheaper to buy a US4 or UST over a DS4 or DST.

3 extra parts, and one part that is much more complicated to machine on the sealed versions. It's a side effect of solving the problem of unsealing. Take your pick on which is more important. For the vast majority of people it's not one worth worrying about

 

[ams511]

3 extra parts, and one part that is much more complicated to machine on the sealed versions. It's a side effect of solving the problem of unsealing. Take your pick on which is more important. For the vast majority of people it's not one worth worrying about

I am familiar with the Apeks product line as I do own several of their products. My main gripe is that they market overbalancing as an advantage to divers and cannot see in any situation where it would be. The IP of a balanced first stage should stay the same regardless of tank pressure or depth.

 

[tbone1004]

I am familiar with the Apeks product line as I do own several of their products. My main gripe is that they market overbalancing as an advantage to divers and cannot see in any situation where it would be. The IP of a balanced first stage should stay the same regardless of tank pressure or depth.

that would be Aqualungs marketing department for you....

 

[CptTightPants21]

Thanks for the link. It is ironic that removing the cap solves the problem but Apeks charges more for regulators with the cap. It is significantly cheaper to buy a US4 or UST over a DS4 or DST.

It is caused by physics. The diameter (surface area) of the seal is larger than the spring which means that there is more space for force to be applied and it is exerting a higher amount of force than just the spring. If the spring and the hydrostatic seal were the same diameter, the amount of force applied would be equal. I suppose Apeks could have designed the seal the same size, but I am sure there were design and cost considerations--you would have to do something, either make the body of the regulator smaller or fill in the gaps with metal. Overall, it beats the hell out of oil and globs of Christolube.

 

[kensuf]

It is caused by physics. The diameter (surface area) of the seal is larger than the spring which means that there is more space for force to be applied and it is exerting a higher amount of force than just the spring. If the spring and the hydrostatic seal were the same diameter, the amount of force applied would be equal. I suppose Apeks could have designed the seal the same size, but I am sure there were design and cost considerations--you would have to do something, either make the body of the regulator smaller or fill in the gaps with metal. Overall, it beats the hell out of oil and globs of Christolube.

How about vodka instead of oil? The freezing point of vodka is -27° C and you can make a wicked martini after a dive.

 

[tbone1004]

How about vodka instead of oil? The freezing point of vodka is -27° C and you can make a wicked martini after a dive.

that's what most people used to put in the caps on the Poseidon first stages when they dry sealed them. I'm not entirely sure on the motives, but they are eerily similar in size and shape to a shot glass....

 

[kensuf]

that's what most people used to put in the caps on the Poseidon first stages when they dry sealed them. I'm not entirely sure on the motives, but they are eerily similar in size and shape to a shot glass....

They probably drank the vodka then concluded that tank swapping while diving sidemount is a reasonable solution.