Unbalanced First Stages

[PilotRPI]

Do any of you know if the Aqualung Calypso is a balanced first stage piston? Isn't quite clear on the site.

 

[Luis H]

Do any of you know if the Aqualung Calypso is a balanced first stage piston? Isn't quite clear on the site.

From the geometry the last time a looked at it, I can tell that it is a flow by unbalanced piston regulator.
If it was balanced they would also advertise it very clearly.

 

[keyshunter]

Do any of you know if the Aqualung Calypso is a balanced first stage piston? Isn't quite clear on the site.

It is an unbalanced piston, similar to the Scubaapro MK2. It currently uses the same second stage as the regular Titan. I have no idea why anyone would buy one, when the regular Titan costs just a little more. But, they keep it in the line, so there must be a market for it.

 

[DA Aquamaster]

It is an unbalanced piston, similar to the Scubaapro MK2. It currently uses the same second stage as the regular Titan. I have no idea why anyone would buy one, when the regular Titan costs just a little more. But, they keep it in the line, so there must be a market for it.

The advantage of a flow by piston design like the MK 2 or Calypso is that they are super simple with very low parts count and only one moving part (the piston).

Also, in that type of design there is no high pressure air downsteam of the seat so the only o-rings exposed to high pressure are usually the HP port plug and at most one more static o-ring sealing the inlet fitting on the first stage.

In addition, there are only two static o-rings and both are only exposed to intermediate pressure, making it better suited to O2 service than the average diaphragm design.

When used as a decompression reg or pony reg, or for that matter as your primary reg, the tendency for the reg to begin breathing harder as the tank pressure falls below 300-500 psi pretty much ensures that all but the most clueless of divers is given clear warning that the tank is nearly empty even if they are not monitoring the SPG.

Finally the seats are usually reversible so a leaky high pressure seat can be quickly fixed in the field.

So while the performance in terms of flow rate is not great and inhalation resistance is generally not as low as on a balanced design, if you want a first stage that is almost bullet proof and simple to service or repair in wthe field, and or one that is well adapted to use on a decompression bottle, a flow by piston design is hard to beat.

 

[keyshunter]

Thanks DA,
I really had not thought of it that way. Do you think that it is much less expensive to produce than the Titan?

 

[Luis H]

Thanks DA,
I really had not thought of it that way. Do you think that it is much less expensive to produce than the Titan?

There is no reason to assume that it is less expensive to manufacture one versus the other.

The Titan does have a large parts count, but many of the parts are used in many regulators; therefore there is a volume advantage.

The manufacturing of the piston and its matting parts does require a tighter tolerance than most of the parts in a diaphragm regulator, so that would add to its production cost.

IMO, the bottom line is that there are too many variables to even guess at any actual production cost.

 

[Slonda828]

+1 to what DA said about unbalanced piston regs being easy to fix in the field. I carry an extra HP seat and O-rings for my USD Aquarius unbalanced piston reg. I can take it apart with a leatherman and completely rebuild it in about 3 minutes if it were ever to fail, which it never has.

Balanced diaphragm/piston regs do have a more stable IP, but you definitely need a clean, shop-like environment to rebuild them IMO. If you can get a calypso III, IV, or VI HP seat out on a dive boat whilst it is rocking and rolling or change the backup ring and its -006 O-ring in a Conshelf spring block on the move, you are a dang good tech. Unbalanced diaphragm regs like the Hydrolung Supreme or Aquadiv Deluxe are also pretty easy to repair with simple tools, but the unbalanced piston is the one I would want to take if I could only take one single hose reg for recreational diving.

Regarding the other posts about unblanced regs, let's not forget the difference between upstream and downstream unbalanced regs. The USD Aquarius is a downstream unbalanced piston reg. It's IP goes down as supply pressure goes down. An upstream unbalanced diaphragm reg like a Hydrolung Supreme or Aquadiv Deluxe's IP goes up as its supply pressure decreases.

Most of this is very succinctly explained in Regulator Savvy, availible at www.scubatools.com

 

[halocline]

What I'd like to see is someone rebuild a MK 2 underwater while buddy breathing. It could be done hovering just to satisfy the DIR crowd.

 

[Slonda828]

What I'd like to see is someone rebuild a MK 2 underwater while buddy breathing. It could be done hovering just to satisfy the DIR crowd.

Dude you are rapidly becoming one of my favorite SB people! Don't forget, it would have to be the same type of MK 2 your buddy had!

 

[herman]

I'm game to try as long as I don't have to breath off of it a the same time.....who has a MK-2 to lend for the challenge??