High Pressure cylinder & Reg. question

[WD8CDH]

<snip> With unbalanced regs like the Scubapro Mk 2 or Aqualung Calypso, it is a noteable concern that requires the reg to be tuned at the maximum service pressure it will see in service.

So far, all of the Calypso regs that I have serviced have been balanced. Is the new model a step backward?

 

[redacted]

So far, all of the Calypso regs that I have serviced have been balanced. Is the new model a step backward?

Aqua Lung: First to Dive

Looks and sounds like an unbalanced piston to me. What mechanism are you seeing that is balancing an inline piston design?

 

[Luis H]

Aqua Lung: First to Dive

Looks and sounds like an unbalanced piston to me. What mechanism are you seeing that is balancing an inline piston design?

I think WD8CDH is talking about vintage Calypso regulators

The Calypso III, IV and J were flow through balanced piston design and they were around from the very early 70&#8217;s.

The original Calypso was a balanced diaphragm design that was around the late 60&#8217;s.
The seat didn&#8217;t have the balancing chamber orifice used in all the other Aqua Lung balanced diaphragm regulators. The air passage was built into the main body around the HP chamber (I believe similar to today&#8217;s Scubapro MK-17). The second stage had a unique exhaust in the middle of the diaphragm with metal exhaust &#8220;T&#8221;.

All the above Calypso first stages were IMO very good designs.

 

[WD8CDH]

Hi Luis,

Isn't the new Calypso also a balanced piston design. Aqualung doesn't specifically state that it is balanced but they say in one of the catalogs that I looked at that the internal parts are usable in their older regulators.

I think the Scubapro MK 2 is balanced too. In general, pistons that have a hole all the way thru the stem are balanced.


AWAP,

Here is a diagram of a balanced piston. Look at figure 3.

http://jclauson.com/msqa/term_paper..._diving_regulators_n_breathing_resistance.pdf

 

[Luis H]

Hi Luis,

Isn't the new Calypso also a balanced piston design. Aqualung doesn't specifically state that it is balanced but they say in one of the catalogs that I looked at that the internal parts are usable in their older regulators.

I think the Scubapro MK 2 is balanced too. In general, pistons that have a hole all the way thru the stem are balanced.


AWAP,

Here is a diagram of a balanced piston. Look at figure 3.

http://jclauson.com/msqa/term_paper..._diving_regulators_n_breathing_resistance.pdf

The latest Calypso looks like the same flow by piston design as a Scubapro Mk-2 (versus flow through as the Scubapro Mk-5 or old Calypso III and IV) .

The Scubapro Mk-2 is definitely not balanced. The tank pressure applies a pressure force at the end of the piston, which in turn affects at what pressure it closes the flow.

In a flow through piston design the high pressure only comes in contact on the cylindrical surface of the piston stem, pushing radial in and not affecting its motion (it doesn&#8217;t push on either end).

Look at the difference in figure 2 versus figure 3 on the write up you quoted.

Thanks for the reference to that write up. I haven&#8217;t read it but first impressions looks good with good diagrams.

 

[pescador775]

Betho, turn on the tank valve and time the freeflow. Generally, if the flow starts immediately the problem is with the second stage. If the flow starts after a slight delay the problem is with the first stage. Problems with the Titan stage are rare. They can involve a damaged seat or stiffness in the small O ring which resides inside the balance chamber. WRT the 2nd stage, as DA mentioned, the second stage seat may be out of adjustment. Small differences or variances in the IP are irrelevant to the second stage performance. Even the balanced Titan may vary slightly according to tank pressure. Plus or minus five psi is probably average and means nothing.

 

[captain]

By any chance was the regulator recently serviced. A friend sent me a regulator that had been recently seviced that had a slight free flow. After replacing all the O rings and inspecting the seats I dould find nothing wrong but it still freefllowed when I reassembled it.After the second tear down I removed the O ring from the balance chamber and used a jewler's loop to inspect the inside wall. Apparently someone had used a sharp pointed metal pick to get the O ring out and badly scratched the inside wall of the chamber. A new chamber solved the problem.

 

[BethO]

I had the reg serviced in the beginning of May and had been diving with it approx. 5-6 times since then with no problems. So I didn't connect the servicing of it with the problem. After reading the posts here though, I took the reg back to the lds again and they adjusted the orifice. That seems to have done the trick and it seems to be working fine now. So far, so good. I really appreciate everyone's help here. Thanks so much-
Beth

 

[pescador775]

By any chance was the regulator recently serviced. A friend sent me a regulator that had been recently seviced that had a slight free flow. After replacing all the O rings and inspecting the seats I dould find nothing wrong but it still freefllowed when I reassembled it.After the second tear down I removed the O ring from the balance chamber and used a jewler's loop to inspect the inside wall. Apparently someone had used a sharp pointed metal pick to get the O ring out and badly scratched the inside wall of the chamber. A new chamber solved the problem.

I did that once when servicing an old Conshelf. The O ring was rock hard and a @%$# to remove. Fortunately, the scratch did not result in a leak. It was only a back up regulator anyway. Later, I replaced the same ring with viton type for some specialty purpose involving oxygen.

 

[captain]

I did that once when servicing an old Conshelf. The O ring was rock hard and a @%$# to remove. Fortunately, the scratch did not result in a leak. It was only a back up regulator anyway. Later, I replaced the same ring with viton type for some specialty purpose involving oxygen.

Shame on you, I know you knew better. Burn them out if they are that hard.