Leak rate

fehler · Post by **fehler** » Tue Feb 19, 2008 12:24 pm

Hi guys,

Can some one tell me the leak rate for the Activa for pressure of 13.

Frank

ozij · Post by **ozij** » Tue Feb 19, 2008 12:35 pm

http://www.internetage.com/cpapinfo/leak-rates-1.html

trice54 · Post by **trice54** » Tue Feb 19, 2008 5:03 pm

Being a newbie, the data stuff is still kinda foreign to me..so I apologize in advance for my ignorance...I went to the link provided in another post and saw the list of leak rates for different masks. So what does the number mean? Say it listed the rate as 29......29 leaks per nite, per hour, what? Thanks!
Trice

dsm · Post by **dsm** » Tue Feb 19, 2008 5:16 pm

Trice,

What the leak rate is, is the amount of air allowed to escape from some small holes in the face or front of each mask.

The leak rate is (IIRC litres per minute) and as the pressure (either the machine varying the pressure, or you breathing in or out against the airflow) changes, the amount of air escaping through the holes varies.

Higher pressure inside the mask = more air tries to escape through the 'leak' holes

Lower pressure in the mask = less air tries to exit the 'leak' holes

The reason for having these 'fixed leak' holes is that as you breathe out, you need to clear the CO2 (Carbon Dioxide) from your lungs and from the mask. If the holes weren't there then the used air when you exhale would stay in the mask and air circuit (tube).

There is a small amount of CO2 that is needed to remain as it is also not desirable to eliminate *all* the CO2. We actually (most of us) need to rebreathe a very small amount of CO2.

The whole air circuit (tube & mask) is designed to strike a balance in regard to clearing used air with its CO2 component.

Cheers

DSM

ColinP · Post by **ColinP** » Wed Feb 20, 2008 1:07 am

dsm wrote:The leak rate is (IIRC litres per minute)...

I think the Respironics measure leaks in litres per minute and the Resmeds do it in litres per second. The quoted leak rates of 29 will be litres per minute, which equates to 0.48 litres / second.

Colin

Edited to fix my mixup between hours and minutes
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CPAPopedia Keywords Contained In This Post (Click For Definition): respironics

ozij · Post by **ozij** » Wed Feb 20, 2008 1:44 am

Colin,
Could you please take a look at you Swift user manual? It should have a graph or table of the intentional leak rate - I can't download from Resmed for some reason.

If PB is anything to go by, then mask leak rates are reported in liters per minute. My machine's software repots leaks in liters per second. But the mask leak table in the manual is in liters pre minute, and I have huch that would be the standard measure for all masks.

O.

ColinP · Post by **ColinP** » Wed Feb 20, 2008 2:32 am

Hi ozij

You're right, the user manual reports in litres per minute, and the actual machine reports in litres per second. I'm only out by a factor of 60!

Apologies to all for creating confusion. I'll edit the original.

Colin

Snoredog · Post by **Snoredog** » Wed Feb 20, 2008 2:34 am

ColinP wrote:
dsm wrote:The leak rate is (IIRC litres per minute)...
I think the Respironics measure leaks in litres per hour and the Resmeds do it in litres per minute. The quoted leak rates of 29 will be litres per hour, which equates to 0.48 litres / minute.

Colin