CPAPtalk.com

ozij wrote:Bumping this up for dsm -
You were on that car trip when I made the discovery - and I wonder if you have any input on the subject.

Thaks,
O.

Ozij,

Got your PM & here I am

One of the few machines I don't have in my possession is that PB420S as I sold it to a friend needing a machine to travel to Japan with.

The photos are on my site and I'll take a look but my 1st thoughts are that because the inside baffles in the PB42x range are very thin foam, I wouldn't be surprised if some were assembled with gaps. The foam is glued into shapes & I think a slipshod assembly would certainly leave unglued foam that might allow air to escape into the housing.

See

http://www.internetage.com/cpapinfo/pb4 ... index.html

DSM

Thanks - I did look at the pictures, but couldn't make it out...
Your explanation makes sense.

O.

[quote="tangents"]What's your reasoning, Snoredog? Even if the white filter restricts the flow, doesn't the software adjust for that on the output? I'm not happy with just the filter that came with the 420E, it's way too porous. My unit has never felt warm in the morning, so I don't think overheating is an issue.

Thanks for everyone's inputs on this thread.

Cathy

Thanks for explaining those pictures, snoredog, that was a big help.

I assume the hole mentioned DME daddy is what we see in center right in picture DSC07709.JPG.

O.

Well, curiosity finally got to me. I reground the tip on my "lucky screwdriver" to fit the 420e (I had uniquely customized those four bevels years ago to fit unlikely places). After taking a peek inside the 420e my opinion is that DME Daddy explained the situation correctly.

ozij wrote:I assume the hole mentioned DME Daddy is what we see in center right in picture DSC07709.JPG.

That assumption is correct, ozij. That hole you see in picture DSC07709.JPG is an orifice on the pressurized (exhaust) side of the air circuit, exactly as DME daddy mentioned. It's a small orifice that diverts just a small amount of air, from front-to-back. It diverts that small amount of air for the purpose of facilitating only the slight amount of heat transfer that is needed across that circuitry. Today's circuitry runs much cooler than yesterday's, but can still sufferer longevity-related fallout if some adequate amount of heat transfer does not occur.

Unlike the 420s orifice in picture DSC07709.JPG, the 420e actually has two such orifices, spaced about one-and-a-quarter inches apart. They do not skew inbound flow sensing, since they are placed after the two clear flow signal lines (two for sequential pressure differentiation of the flow signal on the 420e). Nor do they skew pressure delivery any more than any mask orifices with fixed-rate leak would skew pressure delivery---especially since the 420e uses an altogether different proximal sensor tube to directly measure pressure at the mask (toward servo-motor feedback).


Does anyone know if there are funeral dirges written specifically for former "lucky screwdrivers"?

Thanks for the correct explanation, DME Daddy!! .

-SWS wrote:Well, curiosity finally got to me. I reground the tip on my "lucky screwdriver" to fit the 420e (I had uniquely customized those four bevels years ago to fit unlikely places). After taking a peek inside the 420e my opinion is that DME Daddy explained the situation correctly.

ozij wrote:I assume the hole mentioned DME Daddy is what we see in center right in picture DSC07709.JPG.

That assumption is correct, ozij. That hole you see in picture DSC07709.JPG is an orifice on the pressurized (exhaust) side of the air circuit, exactly as DME daddy mentioned. It's a small orifice that diverts just a small amount of air, from front-to-back. It diverts that small amount of air for the purpose of facilitating only the slight amount of heat transfer that is needed across that circuitry. Today's circuitry runs much cooler than yesterday's, but can still sufferer longevity-related fallout if some adequate amount of heat transfer does not occur.

Unlike the 420s orifice in picture DSC07709.JPG, the 420e actually has two such orifices, spaced about one-and-a-quarter inches apart. They do not skew inbound flow sensing, since they are placed after the two clear flow signal lines (two for sequential pressure differentiation of the flow signal on the 420e). Nor do they skew pressure delivery any more than any mask orifices with fixed-rate leak would skew pressure delivery---especially since the 420e uses an altogether different proximal sensor tube to measure pressure at the mask.


Does anyone know if there are funeral dirges written specifically for former "lucky screwdrivers"?

Thanks for the correct explanation, DME Daddy!! .

and if you wanted to do away with that smaller pressure line inside the hose, you could theoretically move the left connection of that opaque hose up to the center barb shown and do away with that smaller pressure hose.

Machine would then get its feedback pressure from the main hose like most other machines, won't be as accurate a sampling and probably throw off the calibration of the machine, but that is what is done with Respironics machines and others and how they went away from having that separate hose. In fact you could easily re-calibrate the machine since there is an adjustment for making that change.

dsm wrote:

ozij wrote:Bumping this up for dsm -
You were on that car trip when I made the discovery - and I wonder if you have any input on the subject.

Thaks,
O.

Ozij,

Got your PM & here I am

One of the few machines I don't have in my possession is that PB420S as I sold it to a friend needing a machine to travel to Japan with.

The photos are on my site and I'll take a look but my 1st thoughts are that because the inside baffles in the PB42x range are very thin foam, I wouldn't be surprised if some were assembled with gaps. The foam is glued into shapes & I think a slipshod assembly would certainly leave unglued foam that might allow air to escape into the housing.

See

http://www.internetage.com/cpapinfo/pb4 ... index.html

DSM

snoredog wrote: I think you just raised the BS meter another 10 notches SWS and the screw driver is called a Torx.

In a pinch I'll just grind a flat-blade tip to exactly span opposing corners of a Torx inset. Works very well. But hey, thanks for the BS insult.


Correction on the orifices, though. As it turns out those little grey orifices are not orifices. They don't pass air (note to self: get new bifocals). They don't serve as mounting points. And they don't facilitate alignment of anything. So what are they? Beats me. Perhaps they're remnants of the plastic injection-mold process.

But there's a lot of air circulating in there, seemingly by design. I'll post 420e pictures to this thread so everyone can see exactly where the air is sourced. For fun I'll also post a picture of those two 420e protrusions that are different than the 420s picture that everyone is looking at.

The gaps are, indeed, where the air comes from. But you can clearly see the gaps were never intended to fit tightly. And why would that be? A little bit of air transfer toward circuit longevity---unless my professors all used to sling BS.

-SWS wrote:

snoredog wrote: I think you just raised the BS meter another 10 notches SWS and the screw driver is called a Torx.

In a pinch I'll just grind a flat-blade tip to exactly span opposing corners of a Torx inset. Works very well. But hey, thanks for the BS insult.


Correction on the orifices, though. As it turns out those little grey orifices are not orifices. They don't pass air (note to self: get new bifocals). They don't serve as mounting points. And they don't facilitate alignment of anything. So what are they? Beats me. Perhaps they're remnants of the plastic injection-mold process.

But there's a lot of air circulating in there, seemingly by design. I'll post 420e pictures to this thread so everyone can see exactly where the air is sourced. For fun I'll also post a picture of those two 420e protrusions that are different than the 420s picture that everyone is looking at.

The gaps are, indeed, where the air comes from. But you can clearly see the gaps were never intended to fit tightly. And why would that be? A little bit of air transfer toward circuit longevity---unless my professors all used to sling BS.

Snoredog's thermal-transfer design philosophy: "If you can't sear a steak on it, then it ain't gonna ever benefit from circulating air. Besides longevity is for elephants."

I'm going to be sure to use my BS screwdriver as a visual pointing aid in my soon-to-be-released pictures.

Seriously, though, it's never a bad idea to facilitate a little thermal transfer across any circuitry toward longevity. The rubberized boot on the exhaust (pressurized side) is intentionally very loose. I can very easily slide it back and forth with my finger. That's how loose it fits, by design.

And any incidental exit path will do just fine. I personally don't think there's any harm in blocking the RJ11 port to diminish noise. Who wants a 50-year old 420e anyway?

-SWS wrote:Who wants a 50-year old 420e anyway?

Nope, not likely to matter much to any of us .

On a related matter though, with the 420E soon to be displaced by a new design, I have to wonder about stockpiling the older model.

One would hope that the Sandman replacement would be even better than that great lil 420E, but what are the odds, really? Stand-out products are the exception in every industry (duh ..., otherwise they're not standouts, right?), and the replacements generally exhibit regression toward the mean.

Regards,
Bill ( ... wondering if the M-series exhibited regression to the other side of the mean ... )

This is the first I've heard about the Sandman replacement. Is there any information about it?

Cathy

NightHawkeye wrote:

-SWS wrote:Who wants a 50-year old 420e anyway?

Nope, not likely to matter much to any of us .

On a related matter though, with the 420E soon to be displaced by a new design, I have to wonder about stockpiling the older model.

One would hope that the Sandman replacement would be even better than that great lil 420E, but what are the odds, really? Stand-out products are the exception in every industry (duh ..., otherwise they're not standouts, right?), and the replacements generally exhibit regression toward the mean.

Regards,
Bill ( ... wondering if the M-series exhibited regression to the other side of the mean ... )

This may be old news previously discussed. But it looks as if the M-Series will be replaced by the physical design below.

Respironics historically introduces all new physical platforms to their most basic model (CPAP). Then other models eventually receive the same redesigned physical platform.

http://sleepeasy1.respironics.com/

Hope they at least did away with the water leaks and blue lights!