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Scuba Forum / General / March 2005

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balanced piston 1st stage question

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gudmundur - 07 Mar 2005 13:22 GMT
My 1st stage is an Oceanic PX2, but most are built the same way, so
this is a general question,

When you folks dive in sandy, or silty water, do you take any special
steps to keep the crud from getting in through the balancing ports?

I service my own PX2, and spent time removing the buildup of crap that
would accumulate behind the piston, and around the spring. I always flushed
the regulator with fresh clear water, but sand, and silt would remain.
When I now dive under those conditions, I wrap a cotton gauze pad
around the holes, and secure it with two rubber bands.

I have bought some used PX2's over the years as spares, and I just
can't believe the neglect of service these units have seen. Some were
so full of mud, and salt crystals that they were pitted beyond rebuilding.
Makes me wonder about diving with such a person, my attention to detail
may be their life support system some day.
Tony Howard - 07 Mar 2005 20:53 GMT
> My 1st stage is an Oceanic PX2, but most are built the same way, so
> this is a general question,
>
> When you folks dive in sandy, or silty water, do you take any special
> steps to keep the crud from getting in through the balancing ports?

Yes,

I use Apeks regulators which employ a dry-sealing system so don't get crap
inside the 1st stage!

Sell your regs to someone who does not dive in silty waters and get some
Apeks regs.
Adam Helberg - 08 Mar 2005 01:15 GMT
> My 1st stage is an Oceanic PX2, but most are built the same way, so
> this is a general question,
[quoted text clipped - 13 lines]
> Makes me wonder about diving with such a person, my attention to detail
> may be their life support system some day.

The seems to be a trend these days towards balanced diaphragm and away from piston.

Adam
Alan Street - 08 Mar 2005 01:33 GMT
> > My 1st stage is an Oceanic PX2, but most are built the same way, so
> > this is a general question,
[quoted text clipped - 15 lines]
>
> The seems to be a trend these days towards balanced diaphragm and away from piston.

On what do you base this statement?
Adam Helberg - 08 Mar 2005 08:06 GMT
> ? "gudmundur" <hexter@blazenet.net> wrote in message
> ? news:112olbsh52lkabf@corp.supernews.com...
[quoted text clipped - 21 lines]
>
> On what do you base this statement?

It's a general impression from browsing catalogs. For example Oceanic makes both
types of 1st stage but now their dominant design is the diaphragm.

Adam
immerlustig - 08 Mar 2005 09:48 GMT
hi
i used to do regulator services when i worked for a dive store (some
years back, though). we would usually use silicon grease on the spring
for the main purpose of preventing ice build up in cold water. it also
keeps dirt away from the o-rings. the only problem i see with this is
that dirt accumulates if the grease is not replaced regularly. but if
the reg is rinsed properly and the service is done in time it's not
bad. at least in my experience.

the idea with the gauze is quite neat, though.

roland

Signature

immerlustig

Alan Street - 08 Mar 2005 20:43 GMT
> > ?
> > ? The seems to be a trend these days towards balanced diaphragm and away
[quoted text clipped - 7 lines]
> both
> types of 1st stage but now their dominant design is the diaphragm.

And conversely, Scubapro's dominant design is a balanced piston.
Adam Helberg - 09 Mar 2005 00:36 GMT
> ? > ?
> ? > ? The seems to be a trend these days towards balanced diaphragm and away
[quoted text clipped - 12 lines]
>
> And conversely, Scubapro's dominant design is a balanced piston.

True, and there are many other makes such as Atomic and Apeks that make piston first
stage. But Oceanic used to be piston dominant and is now diaphragm dominant-- they've
made a transition. I don't think you can cite an example of a manufacturer going the
other way.  Also, for what it's worth, more diaphragm regulators are appearing as top
performers in Rodale's regulator tests.  I may be wrong but there appears to be
subtle shift.

Adam
H. Huntzinger - 09 Mar 2005 12:58 GMT
> ? > ?
> ? > ? The seems to be a trend these days towards balanced diaphragm
[quoted text clipped - 11 lines]
>
> And conversely, Scubapro's dominant design is a balanced piston.

ScubaPro had been 100% piston for several years.  They're now down to
only three basic models and one of them is the Mk16 diaphragm design
which snuck into the lineup a year or three ago, so now 33% of their
lineup is diaphragm.  I'm currently wondering about the same thing as
Adam:  is there a (perhaps subtle) shift underway, and if so, why?

-hh
Alan Street - 09 Mar 2005 15:13 GMT
In article
<{NOSPAM-rm_to_reply}rec-scuba2005-F36647.07585509032005@news.giganews.c
om>, H. Huntzinger <{NOSPAM-rm_to_reply}rec-scuba2005@huntzinger.com>
wrote:

> > > > ? The seems to be a trend these days towards balanced diaphragm
> > > > ? and away from piston.
[quoted text clipped - 13 lines]
> lineup is diaphragm.  I'm currently wondering about the same thing as
> Adam:  is there a (perhaps subtle) shift underway, and if so, why?

If you take Scubapro out of the equation, I think the mix has been
pretty consistant over the years.

Scubapro gave into what they perceived as a market preference for
balanced diaphragm firsts and, as you nicely put it, snuck one
(actually two at first) design into their line up several years ago. As
I understand it, these haven't been all that popular, especially
amongst two of SP's stronger market segments - rental/entry level and
"high performance" (i.e., divers willing to pay a premium for good gear
because of either a real or perceived need for such kit). Over the
years, SP has had often had 5 or more first stage designs that
attempted to address different parts of the market spectrum, including
BD designs competing with BP designs for the same market space (i.e.,
market segmentation run amok).

They've now simplified their line of first stages to one top of the
line, high performance balanced piston that addresses one of their
strongest market segments, one middle range balanced diaphragm design
that addresses the mid market (where they're not so strong),  and one
"value line" unbalanced piston design that addresses the entry
level/rental market (where they probably make most of their profit). If
you look at this simply in terms of the number of models offered today
compared with the number of models offered a few years ago, you might
come to the conclusion that SP has "shifted towards" BD designs. But if
you look at it in terms of where they're strongest and what sells the
most for them, it doesn't. Their strongest designs are aimed squarely
at their strongest market segments, and they've got a decent BD design
targeting their weakest market.

Alan
Curtis - 09 Mar 2005 02:43 GMT
>> On what do you base this statement?
>
> It's a general impression from browsing catalogs. For example Oceanic
> makes both types of 1st stage but now their dominant design is the
> diaphragm.

   Okay, I understand now,  you base your statement on looking at the
pictures rather than from sales records, what's in use for rentals, or
actual use by recreational and technical divers, or which regs are bought as
first purchases and what is bought as subsequent purchases.

   Scott was right.

Curtis
Scott - 09 Mar 2005 02:56 GMT
> >> On what do you base this statement?
> >
[quoted text clipped - 8 lines]
>
>     Scott was right.

sshhhhhh!
Curtis - 09 Mar 2005 03:00 GMT
>>     Scott was right.
>
> sshhhhhh!

   He's really gonna be disappointed when he looks at Playboy then goes to
the beach.......

Curtis
Scott - 09 Mar 2005 03:05 GMT
>     He's really gonna be disappointed when he looks at Playboy then goes to
> the beach.......

<cough>

Yeah, those chicks hang at, like, the mall...
Curtis - 08 Mar 2005 01:36 GMT
> The seems to be a trend these days towards balanced diaphragm and away
> from piston.

   Oh, really?

Curtis
Al Wells - 08 Mar 2005 21:38 GMT
> > The seems to be a trend these days towards balanced diaphragm and away
> > from piston.
>
>     Oh, really?

Are you using the Beuchats?
Scott - 08 Mar 2005 01:39 GMT
> The seems to be a trend these days towards balanced diaphragm and away from piston.

This compares with your firearms expertise.
Curtis - 08 Mar 2005 01:41 GMT
>> The seems to be a trend these days towards balanced diaphragm and away
> from piston.
>
> This compares with your firearms expertise.

   Well, there's 3, in just minutes.......

Curtis
andrew m. boardman - 08 Mar 2005 06:15 GMT
>When you folks dive in sandy, or silty water, do you take any special
>steps to keep the crud from getting in through the balancing ports?

The ambient chamber on the BP reg I use in cold and silty water is packed
with silicone grease (Dow-Corning 111).  It keeps the crap out and
everything exposed in the ambient chamber in *much* nicer shape when it
comes apart again, though getting rid of the grease is a bit of a pain.
I'd be surprised if Oceanic didn't suggest something similar; check your
service info for "cold water kits" or similar.

Keep it the hell away from high pO2, though.
 
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