Regulator Choice

[Diver-Drex]

In my opinion, there is little difference between $400 regs and $1000 regs for recreational diving. Even for technical diving, proper servicing and setup is more important than brand name and the latest technology.

Find out what brands your local shop carries and services. You’ll need to get your regs serviced and your LDS will appreciate the business, even if you don’t buy the regs from them. And you’ll appreciate not having to ship your regs out any time something isn’t quite right.

Also, give the shop a chance to earn your business on the sale. They may be willing the price match or at least do much better than MSRP.

 

[Bigbella]

I am about to buy myself a regulator. I did some browsing and found a few of them and I am confused. so my question really boils down to asking you whether I need to get the latest and most advanced model. I have just started diving and did about 10 dives. Or am I better off buying are used prior model? Is there a radical difference between those? Or is it marketing mostly?

Consider, for a moment, that the technology of every open circuit, single hose regulator, can trace its origins to the late 1950s; and, while cosmetic materials have changed over the years, the "guts" have largely not. I have used both piston ( "unbalanced" or "compensated") and diaphragm ("balanced") regulators for decades -- still use both, as a matter of fact.

My advice, would be to choose an established name brand, and the best that you can comfortably afford, if you're likely to hold onto the equipment for more than a few years. I recently saw a display of discontinued regs, just from two decades; and those defunct brands and models far outnumbered every one that I had ever seen, as a novice). A number of companies have come and gone; but there are a few mainstays, which still carry parts for even some of their oldest regulators.

That is why I still consider ScubaPro and Poseidon to be the Nikons of the diving industry . . .

 

[Alex Chernov]

Ok, so I bought this one.

SOLD!!! - Closed

 

[BlueTrin]

Ok, so I bought this one.

SOLD!!! - Closed

Enjoy

 

[JackD342]

Enjoy

Good choice. Looks like the 1st generation Legend LX. If you ever want to try it in colder water, first have your LDS adjust the IP to the lower range for the Legend LX Supreme.

 

[Bigbella]

Good choice. Looks like the 1st generation Legend LX. If you ever want to try it in colder water, first have your LDS adjust the IP to the lower range for the Legend LX Supreme.

Strange.

I was always taught, and recall from an ice diving class a life ago, that that lowering of the IP to avoid potential freezing / free-flow, was a myth -- that adiabatic cooling of the air in the regulator, the primary concern, would even be marginally greater at a lower IP -- the 1st stage having been required to plummet to a more extreme degree, from 200 bar to, say, 8, at the second stage, rather than a typical 10 (admittedly a small difference; but a bit colder nonetheless), just by lowering the IP 1-1.5 bar; and we never did that for any cold water diving, that I can recall.

We always -- effectively -- went the environmental cap route, with the vodka, and felt a bit sad for those with the first stages, stuffed to the gills, with silicone grease.

Skål . . .

 

[JackD342]

Strange.

I was always taught, and recall from an ice diving class a life ago, that that lowering of the IP to avoid potential freezing / free-flow, was a myth -- that adiabatic cooling of the air in the regulator, the primary concern, would even be marginally greater -- the 1st stage having been required to plummet to an even greater degree, from 200 bar to, say, 8, at the second stage, rather than 10 (admittedly a small difference; but colder nonetheless), just by lowering the IP 1-1.5 bar; and we never did that for any cold water diving, that I can recall.

We always -- effectively -- went the environmental cap route, with the vodka.

Skål . . .

Cold water resistance is affected by the sum effect of multiple factors, not by a "single, one size fits all solution." You described a viewpoint that only cares about the 1st stage, but forgets that the 2nd stage can also freeze. I suspect on many designs the heat exchange is more efficient on the 1st than on the 2nd, and so delivering lower IP to the 2nd is the design choice.
Regardless, for whatever reason, that generation of Legend specified a lower IP for the Supreme for coldwater use, which is what was tested and approved for the EU coldwater standards.

 

[Bigbella]

Cold water resistance is affected by the sum effect of multiple factors, not by a "single, one size fits all solution." You described a viewpoint that only cares about the 1st stage, but forgets that the 2nd stage can also freeze. I suspect on many designs the heat exchange is more efficient on the 1st than on the 2nd, and so delivering lower IP to the 2nd is the design choice.

Freezing is all about the first stage, which experiences the most tremendous pressure extremes, in the course of a second or less, upon opening a valve; and, consequently, a precipitous temperature drop, due to adiabatic cooling; that, and the influence of residual moisture, left in the breathing air.

While I didn't mention the second stage outright; didn't think it required explicit comment -- but the consequences of free-flow obviously ends right there; and its likelihood, it seems to me, would be even greater, with incrementally colder air from the first stage, even with just a 1-2 bar pressure decrease. Also, unless the second stage is well-tuned, to be used beyond factory specs, in terms of cracking effort, the breathing will, well, suck . . .

Regardless, for whatever reason, that generation of Legend specified a lower IP for the Supreme for cold water use, which is what was tested and approved for the EU cold water standards.

Thermodynamically, it just doesn't seem to add up; it's counterintuitive; can't quite see the rationale of purposely de-tuning a regulator. Harlow briefly mentions the occasional practice in his book; but doesn't seem to draw any conclusions as to its real effectiveness -- just says it's done; and I have used the Poseidon Cyklon at near freezing temperatures over the years, with the environmental cap; and its IP is about, if not, the highest of any manufacturer, at about 11.6 bar . . .

 

[JackD342]

Freezing is all about the first stage, which experiences the most tremendous pressure extremes, in the course of a second or less, upon opening a valve; and, consequently, a precipitous temperature drop, due to adiabatic cooling; that, and the influence of residual moisture, left in the breathing air.

While I didn't mention the second stage outright; didn't think it required explicit comment -- but the consequences of free-flow obviously ends right there; and its likelihood, it seems to me, would be even greater, with incrementally colder air from the first stage, even with just a 1-2 bar pressure decrease. Also, unless the second stage is well-tuned, to be used beyond factory specs, in terms of cracking effort, the breathing will, well, suck . . .



Thermodynamically, it just doesn't seem to add up; it's counterintuitive; can't quite see the rationale of purposely de-tuning a regulator. Harlow briefly mentions the occasional practice in his book; but doesn't seem to draw any conclusions as to its real effectiveness -- just says it's done; and I have used the Poseidon Cyklon at near freezing temperatures over the years, with the environmental cap; and its IP is about, if not, the highest of any manufacturer, at about 11.6 bar . . .

@Alex Chernov first, I need to back track. That is actually the 2nd generation Legend, and tuning is the same for both Supreme and standard. The only non cosmetic difference between the two that I have found is a different 2nd stage exhaust valve, (perhaps stiffer for the Supreme?) and the included lip shield. The 2nd stage however should be tuned differently for the Supreme configuration.

@Bigbella I absolutely agree to not go around randomly changing manufacturer spec tuning and then calling it suitable for coldwater. In at least this instance though, the different tuning IS the manufacturer spec. For 1st generation Legend LX, the only parts differences were whether or not the 2nd stage case had a snowflake printed, and the tuning on both stages.

It feels like you are forgetting the adiabatic cooling that occurs in the 2nd stage. Freezing is NOT “all about the first stage” regardless of what you intuit. Heat exchangers on 2nd stages, special coatings, choice of 2nd stage materials, even rubber versus braided hoses ALL impact 2nd stage freeze up.

 

[Bigbella]

@Alex Chernov

It feels like you are forgetting the adiabatic cooling that occurs in the 2nd stage. Freezing is NOT “all about the first stage” regardless of what you intuit. Heat exchangers on 2nd stages, special coatings, choice of 2nd stage materials, even rubber versus braided hoses ALL impact 2nd stage freeze up.

I was not forgetting about the second stage; but there's a considerable difference with that component, descending only from 10 bar to ambient pressure, compared to that of the first, from, say, 200 to 10 bar. I have never had a freezing issue or a temperature related free-flowing issue with mine, despite a wholesale absence of any heat exchangers; any special coatings of which I am aware; or, for that matter, the variety of hoses that I have had, even though there was, on occasion, a thick accumulation of ice on the first.

Why would a reduced IP on my regulators, prove to be inimical, while other brands, as you have said, actually call for it, in their specs? At some point in the mix, one balanced diaphragm regulator and another, are largely the same, in terms of components. Why, then, the disparity?