CPAPtalk.com

-SWS wrote:

snoredog wrote: More specifically the safety grate which places a restrictive obsticle in circuit of flow."

Restrictive as in a bona fine impedance concern? Based on Roberto's input above I don't think so.

The grating may have significant transient surface-deflective issues. Right about now I'm very seriously doubting that. Like you, Snoredog, I don't have one of these diffusers in my posession to make accurate physical assessments. Roberto's physical assessment sounds pretty fair to me right about now.

My experience tells me ANY resistance added to the circuit is going to impact the sensitivity of the machine to respond.

No ifs ans or butts about it. Granted my experience comes from greater velocity pressures than what we are dealing with here as the smallest ID I ever tested was 4" diameter with up to 10" wc.

But the law of physics remains the same only scaled down. The biggest problem will be finding instruments sensitive enough to test it. Oh yeah, many blowers have a safety grate installed right at the blower inlet, we would cut those out as they were found way too restrictive.

Hey, I'm no expert, but I've done a bit of testing on my own, here's some I did in my garage and speak from experience not reading it in some book somewhere.

Here's my bench test platform, you won't have any apnea's with this one. What you see taped to the black pipe near the inlet to the blower (inside the pipe) is a precisely calibrated pitot tube made by Dwyer instruments specifically for this purpose.

The blue funnel on the end is a control valve, it opens up air flow to a specific static pressure for determining flow. The airflow passes by the facing pitot tube where velocity pressure can be measured. This pitot tube is very similar to those used on airplanes to measure velocity air speed. With it I can test from zero flow to maximum flow rate in 1" increments by simpy dialing it in, flipping the valve on the magnehelic and taking the reading.

snoredog wrote:My experience tells me ANY resistance added to the circuit is going to impact the sensitivity of the machine to respond.

See Roberto's posts above about sum-total cross-sectional or pass-through area. From what I can tell there is no significant resistance added. Just a little negligible surface drag and deflection.

So far I still don't see a flow-signal problem with PurSleep.

-SWS wrote:
So far I still don't see a flow-signal problem with PurSleep.

but then again, you are only guessing and don't know either.

Well I admit I don't know ... but my best guess is that there is very very minimal effect on the flow signal (especially if the diffuser was placed near the mask end of the circuit). Becasue it is suggested to be placed at the machine end of the circuit, it may have a minimal transient effect ... however, if an HH is between the diffuser and the machine ... transient effects will very likely be nil also.

Just my best guess ... but what do I know? ... I don't work for the FDA

OMG! All this over a little in-line aromatic diffuser????? Dear Lord, hurry up Bret, will ya?????

Right, in the meanwhile I found those photos, too, and see how this thing is made:



I think the whole discussion now changes from resistance to turbulence. It's even more important that flow characteristic studies be carried out to insure that all that stuff in the middle there doesn't create an area of local eddies and result in turbulent flow. Depending on that quantity (which in turn could vary with flow rate), a back pressure could develop that would result in a pressure gradient. There could be significant differences pre- and post- turbulent flow. Further, the waveform must now out of necessity be looked at through all the therapeutic flow rates.
SAG

GuestForADay wrote:OMG, OMG – PLEASE DON’T let it be over!
It’s better than GWTW!

The only thing left to do … would be to cast the movie version:

Working Title: One Flew Over the Sleep Apneas’ Nest

Starring:
SG …………………………….Russell Crowe
CQ ……………………………Cate Blanchett

In alphabetical order:
blarg………………………….George Clooney
Daniel ………………………Liam Neeson
(from sleepapnea.org)
drb…………………………….John Malkovich
dsm……………………………Robin Williams
FDA agent ……………… Kevin Costner
MrMango……………………Crocodile Dundee
(from talkaboutsleep.com)
NightHawkeye.........oooh I can't think of anyone...Tom Hanks
RestedGal…….………….Joan Allen
Ric …………………………… Jim Carey
SAW…………………………..Kevin Bacon
telly……………………………Jon Lovitz
Denzel Washington …………..Denzel Washington

Special Guest Appearances:
Kavanaugh…………………….Sarah Jessica Parker
bookworm……………………. Kelly Ripa

LOL Loudly

Than goodness I'd finished my morning coffee

DSM

Again, I think there would be no more turbulance/back pressure issues than placing an HH in that same location.

SAG wrote:It's even more important that flow characteristic studies be carried out...

As long as we don't have to study it using that gizmo in Snoredog's garage.

Seriously, though, would love to see Snoredog's garage gadgetry some day. He's got cool looking stuff.

StillAnotherGuest wrote:Right, in the meanwhile I found those photos, too, and see how this thing is made:



I think the whole discussion now changes from resistance to turbulence. It's even more important that flow characteristic studies be carried out to insure that all that stuff in the middle there doesn't create an area of local eddies and result in turbulent flow. Depending on that quantity (which in turn could vary with flow rate), a back pressure could develop that would result in a pressure gradient. There could be significant differences pre- and post- turbulent flow. Further, the waveform must now out of necessity be looked at through all the therapeutic flow rates.
SAG

SAG I know you are joking aren't you ? - with airflow of say 8-10 lpm you are concerned about eddies ?.



Dunno why the logistics of this innocent little device are so entertaining.

As DreamStalker pointed out - an HC150 will create air buffereing - I would speculate that more than 5 diffusers joined together would still not have anywhere near the effect an HC150 would.

Hey, there is a challenge - I'll bet that anyone who places 5 diffusers (only 1 sniff ball with actual aroma in it ) inline and measures their nightly data, on a Remstar Auto or a Resmed Auto, will not see any difference from their usual average.

On a Vpap III, I'll bet the same applies & the minute volume will also show no variation.

So theres a challenge - SleepGuy - I need 4 more diffusers

DSM

(yes am being humourous )

_________________

CPAPopedia Keywords Contained In This Post (Click For Definition): resmed, auto

-SWS wrote:

SAG wrote:It's even more important that flow characteristic studies be carried out...

As long as we don't have to study it using that gizmo in Snoredog's garage.

Seriously, though, would love to see Snoredog's garage gadgetry some day. He's got cool looking stuff.

ah that's nothin, I made a cyclone also, you should see my homemade router table.

http://home.pacbell.net/jdismuk/routertable.html

As an after post & just for those who won't have picked up on it (entirely understandable)

The photo SAG posted appears to have a basic flaw in it. When I used the Pur-sleep I stated that I put it at the mask end because my Puritan Bennett machine (as is the machine in the SAG photo) has an internal pressure line & thus one can't easily put the diffuser at the machine end.

I also made the point that putting it at the mask end made no difference to the nights sleep - I did not even notice the difference of it being there compared to it not (other than the aroma).

DSM

-SWS wrote:

SAG wrote:It's even more important that flow characteristic studies be carried out...

As long as we don't have to study it using that gizmo in Snoredog's garage.

Seriously, though, would love to see Snoredog's garage gadgetry some day. He's got cool looking stuff.

SAG also has delicate monitoring instruments:



SAG

StillAnotherGuest wrote:

-SWS wrote:

SAG wrote:It's even more important that flow characteristic studies be carried out...

As long as we don't have to study it using that gizmo in Snoredog's garage.

Seriously, though, would love to see Snoredog's garage gadgetry some day. He's got cool looking stuff.

SAG also has delicate monitoring instruments:



SAG

ah yes, Papa & baby BFH's!!

dsm wrote: SAG I know you are joking aren't you ? - with airflow of say 8-10 lpm you are concerned about eddies ?.



Dunno why the logistics of this innocent little device are so entertaining.

Just don't put any FDA approved peanut butter on that little scent pad cuz when you combine that with the cyclonic turbulance and eddy induced backflow pressures ... you may just have one deadly peice of medical equipement on par with flatulence