picking out first reg and question about a "balanced" second stage

[rscott9399]

Implementation details really. My main 1st stages have upstream-opening valves (except some older Calypso and Aeris 1st stages which are downstream pistons), and my 2nd stages are all downstream-opening. In theory downstream-opening valves are less likely to fail shut, but actual dive experience with various regulator designs doesn't bear that out in practice.

Yikes...
You mean to say you have had a reg fail where it failed closed?
That is scary.

 

[boulderjohn]

@OkByMe please enlighten me on where I can rent a MK25/S600 or any other high end regulator. I'd love to know because I don't know anyone who has them in a rental fleet. I know a few demo centers in cave country where you can test some of the high end regulators, but am unaware of any that do that with Scubapro

Actually, that first shop where I worked rented that exact setup. They hoped having good regulators would inspire the customers to make a purchase of that quality.

 

[boulderjohn]

are you claiming that @boulderjohn is lying about his experience that caused him to leave his shop?

What I did not mention is that they learned to do this via a marketing workshop (which I attended) conducted by the owner of the dive agency to which they were switching. It was a workshop he gives regularly across the country. One of the things he advised and which I would have had to do if I had stayed was have all the instructors purchase and wear the same gear, the specific items the shop was pushing. It would be our "scuba uniform." We would be told to tell the students that we had selected those items because they were the best, and as instructors, we wanted only the best. We were to wear those specific items whenever we were in the presence of the students, and we could not tell them that we used anything different in our personal diving. The only item on the list I would have used in my own diving was the wetsuit.

 

[tbone1004]

@boulderjohn that was being a bit facetious as I actually know a shop that does it, but they are certainly few and far between to find and you have to go hunting for them. Not worth the effort.

 

[ams511]

@OkByMe please enlighten me on where I can rent a MK25/S600 or any other high end regulator. I'd love to know because I don't know anyone who has them in a rental fleet. I know a few demo centers in cave country where you can test some of the high end regulators, but am unaware of any that do that with Scubapro. I think one of them now may do it with Atomic and @Kristi@CCDS can confirm if they do, but unaware of others.

Never been there but Casey at Beaver Divers claims his shop rents MK-25/S600. I was shocked as most other places that rent Scubapro you get an MK-2/R295. When I learned how to dive, my regulator set was a MK-5/Air I. Which I guess was fairly decent at the time. I bought a Conshelf 21 because it was cheap and it worked.

 

[halocline]

Hello all

I dont want to spend a lot but a few things i would like after a Snuba experience on a cruise is a reg that flows nicely. While doing a Snuba trip i was not able to tilt vertical in the water. The reg became very hard to breath from and was forced to look strait down the whole time.

As a pilot myself, i like NEW things when it comes to life support devices such as "airplane engines"

I have a little extra coin so why not?
I can spend more then $300 but dont want to spend $800 either.

I see that the C350 is "downstream" and not a balanced second stage
What does this mean exactly?

I'll try to succinctly answer some of your questions:
1. The 2nd stage receives pressurized air from the 1st stage via the hose. This pressure in the hose is called "intermediate pressure" or IP. The IP is constantly pushing on the valve in the 2nd stage, trying to open it, and is strong enough so that it must be countered by a spring in the 2nd stage. When you inhale, a flexible diaphragm in the 2nd stage collapses, pushing on a lever, which then pushes open the valve and compresses the spring. You want this effort to be as low as possible, which means you want a spring which will precisely counter the pressure of IP (from the 1st stage) but not over-counter it by much. That would mean more work in pushing the valve open and compressing the spring. Make sense?

Okay, so an unbalanced 2nd stage is exactly that; IP pushing against a carefully selected metal spring. So, if the IP were to change significantly, the 2nd stage would either open on its own (free flow) or be much harder to breathe, depending on whether or not IP went up or down. Still make sense?

A balanced 2nd stage takes air pressure from the hose (IP) and diverts it into the 2nd stage so that it assists a much smaller spring, in essence turning the air pressure to push against itself on both sides of the 2nd stage valve. Since now most of the force opposing the IP (from the 1st stage) is now the same air pressure pushing back, changes in IP have a much smaller impact on how difficult it is to open the valve (breathing effort). For example, if IP were to drop by 20 PSI, so would the air pushing back against it, where in an unbalanced 2nd stage, that lower IP would still be working against a full size spring.

What this means in terms of practical diving experience is that a balanced 2nd stage will tolerate big changes in IP much better than an unbalanced 2nd stage. This is only important if you have a 1st stage that does not provide a steady IP. Most do; in fact that is the purpose of a balanced 1st stage. So if you have a balanced 1st stage, it is much less important to have a balanced 2nd stage. There are lots of other details and small factors, but that's the gist of it.

2. Your other questions are much easier to respond to because you really have to answer for yourself how much you want to spend. First, understand that there is a great deal of hype in regulator sales, and students are frequently sold much more expensive regulators than they need or than will even provide a safe, fun diving experience.

In fact, the main reason that dive shops offer certification classes is to sell the students expensive gear. You can't blame them; they are in business and their students are their primary market. Many new dive students want to spend money on their new hobby; its human nature.

Second, do not equate "new" with "safe" and do not get fooled into thinking that regulators are devices that your life depends on. Both of those myths are frequently perpetuated by dive instructors at shops, because, again, the students are there because the shop wants to sell them gear. The old 'life support' bit works like a charm... Few things will inspire taking out that credit card better than fear of drowning!

So, decide between "I don't want to spend a lot" and "I have a little extra coin so why not.." It's your money and you decide how to spend it. But you can certainly get excellent used older regulators for a very low price that are every bit as good performing and safe as new ones. The basic designs have not changed in decades.

As an example, I use a MK10/D300, for which I paid $84, in caves, where a regulator failure really can get scary quickly, because you have no immediate access to the surface. Of course even in those situations you always plan for sharing air and have alternate means of survival in case your regulator suddenly stops working.

So get what you want, but don't think that you're buying yourself any additional safety by getting an expensive or even new regulator. They just need to be well maintained and serviced correctly. It's not rocket science.

Guess I failed on the 'succinctly' part!

 

[shurite7]

[QUOTEplease enlighten me on where I can rent a MK25/S600 or any other high end regulator. I'd love to know because I don't know anyone who has them in a rental fleet. I know a few demo centers in cave country where you can test some of the high end regulators, but am unaware of any that do that with Scubapro. I think one of them now may do it with Atomic and @Kristi@CCDS can confirm if they do, but unaware of others.[/QUOTE]

I know of two shops which rent the Mk25/S600 regulators, a guy in Spokane and the shop I run in MT. I rent the Mk25/G260, Mk21/S600, Mk17/G260 (used to be the Mk17/A700, but a customer really wanted the A700), XTX50, and XTX 200. I also have several Mk2/R195 and Aqualung Calypso type regs in the rental pool. I prefer to rent the nicer regs because they function better in the cold mountain lakes. The unbalanced first stage style regs work fine in the pool and during the summer open water certifications. During the AOW course or during the colder months I prefer that my students use the nicer regs.

So, there you go, two dive shops that rent the Mk25/S600. Granted, this is rare.

 

[cerich]

What I did not mention is that they learned to do this via a marketing workshop (which I attended) conducted by the owner of the dive agency to which they were switching. It was a workshop he gives regularly across the country. One of the things he advised and which I would have had to do if I had stayed was have all the instructors purchase and wear the same gear, the specific items the shop was pushing. It would be our "scuba uniform." We would be told to tell the students that we had selected those items because they were the best, and as instructors, we wanted only the best. We were to wear those specific items whenever we were in the presence of the students, and we could not tell them that we used anything different in our personal diving. The only item on the list I would have used in my own diving was the wetsuit.

All delivered by Doug in a earnest mega church type address..

 

[ams511]

All delivered by Doug in a earnest mega church type address..

How long has he been doing that? @boulderjohn described my open water instructor perfectly. I was certified in 1990 or 91.

 

[2airishuman]

Yikes...
You mean to say you have had a reg fail where it failed closed?
That is scary.

Though rare, it does happen. I dive accordingly. It has not happened to me personally.

The most serious equipment failure I have suffered during a dive was a separation of the mouthpiece from the second stage.