Does the Airfit F10 vent excessively ?

Gasper62 · Post by **Gasper62** » Sun May 10, 2015 11:06 am

While I was trying to use the "mask fit" feature for my new Airfit F10 mask on my new S9Autoset, the red frowny face would show up even when I knew that I had a pretty darn good mask seal. It seems to me that the circle of vent holes plus the swivel gasket arrangement are venting too much air pressure and making the machine "believe" it is a cushion leak. This mask really vents A LOT of air, so, I experimented by wetting some Kleenex and used it to block the vent holes for half of the way around the ring. It then felt more like my other FFMs on exhale and.... the happy, green mask-fit face was back ! As far as I know, I didn't suffer any CO2 poisoning in the 6.6 hrs. I slept ! How would/can an S9 differentiate/compensate for excessive venting from a certain mask ? Is there a menu setting that I've missed maybe ? The "spitball" fix isn't very elegant but, at least, it's effective !

palerider · Post by **palerider** » Sun May 10, 2015 11:25 am

Gasper62 wrote:While I was trying to use the "mask fit" feature for my new Airfit F10 mask on my new S9Autoset, the red frowny face would show up even when I knew that I had a pretty darn good mask seal. It seems to me that the circle of vent holes plus the swivel gasket arrangement are venting too much air pressure and making the machine "believe" it is a cushion leak.

no, it doesn't. it's vent rates are consistent with the majority of masks on the market. (check the chart in the back of the manual)

you've either got leaks somewhere that you're not noticing, (cats eating the hose?) or you've got a defective mask.

RogerSC · Post by **RogerSC** » Sun May 10, 2015 11:26 am

There is a setting for mask type in the S9 menus. That is supposed to help correct for a mask's normal venting. The setting that I'm using is "nasal pillows" and works fine for me, but since nasal pillows don't vent as much as a full face mask, not setting this one appropriately could be your problem. If you haven't set this already *smile*.

Gasper62 · Post by **Gasper62** » Sun May 10, 2015 11:45 am

I do have the mask type set to FFM. I'm beginning to think that this mask might be somewhat defective or, I'm becoming incapable of detecting cushion leaks. maybe I'll try the soapy water test like is used for tires and tubes, see how many places blow bubbles !

palerider · Post by **palerider** » Sun May 10, 2015 12:16 pm

RogerSC wrote:There is a setting for mask type in the S9 menus. That is supposed to help correct for a mask's normal venting. The setting that I'm using is "nasal pillows" and works fine for me, but since nasal pillows don't vent as much as a full face mask, not setting this one appropriately could be your problem. If you haven't set this already *smile*.

while others don't agree with me, I believe that this commonly held idea is wrong.

if you look at a chart of resmed mask vent rates, and add in others from other manufacturers. you'll find that they all vent at approximately the same rate. around 20lpm @4cm to around 50lpm@20cm, there are minor differences, but they are minor.

however, if you look in the manuals for the masks and look at their RESISTANCE specs, they all pretty much line up with full face having the lowest resistance, nasal having slightly higher, and pillow masks having the greatest resistance.

this data leads to the conclusion that the mask type setting in the resmeds is so that the machine can adjust it's pressures to compensate for the resistance that the different masks provide, in much the same way that the hose type setting allows it to compensate for the different types of hoses.

Code: Select all

pressure   p10     f10
4          20      22
8          29      32
12         37      41
16         43      48
20         49      54

less, yes, but not enough to trigger a leak alert.

contrast that with the resistance, with the p10, @50lpm, .4cm @100lpm, 1.4cm f10: @50, .2cm @100 1.0cm.

knowing the pressure you've set, and the type of hose and mask, the machine can raise the pressure where it's measured (by the air outlet) to compensate for the pressure drops at the mask, and thus give you the desired pressure.

library lady · Post by **library lady** » Sun May 10, 2015 9:53 pm

I use AirFit F10; rarely do I register large leaks either on the machine readout or on Sleepyhead. In fact, Sleepyhead hardly ever shows leaks that go above the red line, so I don't think it's a reasonable assumption that F10 is an excessively leaky mask. You are right that it blows a lot of air but I don't think that is indicative of anything more than the venting that is built into the mask design to prevent rebreathing.

Jay Aitchsee · Post by **Jay Aitchsee** » Mon May 11, 2015 4:41 am

palerider wrote:this data leads to the conclusion that the mask type setting in the resmeds is so that the machine can adjust it's pressures to compensate for the resistance that the different masks provide, in much the same way that the hose type setting allows it to compensate for the different types of hoses.
...contrast that with the resistance, with the p10, @50lpm, .4cm @100lpm, 1.4cm f10: @50, .2cm @100 1.0cm.

Interesting theory, but those pressure drops stats are given at fairly high flow rates (50 and 100lpm) which would generally correspond to static vent rates at pressures of 20cmH2O and higher. But even at 50lpm the difference in resistance for the two masks is only .2cm. Since, I think, resistance is a function of the square of flow, the absolute difference in the two at more typical values of use would be even less.

I'm just sayin'

Edit: In thinking about this a little more, it may not make any sense to talk about static vent flow rates in conjunction with Resistance. Maybe Minute Ventilation would be more appropriate? Mine is about 30Lpm max and 8 average with FFM and 15lpm max and 7 average w/ pillows. Don't know, it is interesting.

adipasqu · Post by **adipasqu** » Mon May 11, 2015 9:26 am

I am on my second F10 and the leak rate on my first was about 50% higher than on my second. In fact, my first would give large leak flags at higher pressures regularly. My second has yet to give me a large leak flag at all. I never really did any troubleshooting on my first mask, but I figured the extra leaking was coming from the removable elbow since the seal on that appears to be the weak link to me. You could try replacing the elbow to see what that does to your leak numbers.

JDS74 · Post by **JDS74** » Mon May 11, 2015 11:20 am

Instead of the Kleenex approach, you might try an external seal around the elbow connection, it shouldn't be leaking any significant amount from that connection.

If that imploves enough to get rid of the Red Frowny Face during Maskfit, then, as Palerider suggests, the mask may be defective.

palerider · Post by **palerider** » Mon May 11, 2015 11:31 am

Jay Aitchsee wrote:Edit: In thinking about this a little more, it may not make any sense to talk about static vent flow rates in conjunction with Resistance. Maybe Minute Ventilation would be more appropriate? Mine is about 30Lpm max and 8 average with FFM and 15lpm max and 7 average w/ pillows. Don't know, it is interesting.

it sounds to me like you're onto something there...

to get the applicable flow rate, you'd have to look at the expected flow @presssure, say, 35lpm@10ish cm. then add in the varying flow from breathing, looking at one night of my data, I see breathing flows up to 120lpm, though usually more like 30-60.

that gives a wide range of flow from 65-155lpm on the plus side.

without the mask type compensation, your actual delivered pressure would vary more, I think that respironics resistance control is their way of copying the idea in the 60 series, but they got more specific. it makes perfect sense to me,

without the added compensation for the flow resistance of the masks, the final end pressure isn't nearly as accurate.

Gasper62 · Post by **Gasper62** » Mon May 11, 2015 12:29 pm

I am pretty sure that my "cushion to face" seal is fairly "airtight", it seems very similar to my Hans Rudolph mask fit. I was hoping to have success with the Airfit F10 because the HR weighs a TON in comparison to the lightweight F10. I just read some "fine print" in the Airfit manual.

"The mask contains passive venting to protect against rebreathing. As a result of manufacturing variations, the vent flow rate may vary."

Maybe I'll take the thing to a speed shop and have em test the actual airflow like they do with carbs and manifolds !

Gasper62 · Post by **Gasper62** » Mon May 11, 2015 12:32 pm

adipasqu wrote:I am on my second F10 and the leak rate on my first was about 50% higher than on my second. In fact, my first would give large leak flags at higher pressures regularly. My second has yet to give me a large leak flag at all. I never really did any troubleshooting on my first mask, but I figured the extra leaking was coming from the removable elbow since the seal on that appears to be the weak link to me. You could try replacing the elbow to see what that does to your leak numbers.

Hmmmmmm, that is very interesting that there was a 50% difference between two masks. (more than a little alarming too ! )

palerider · Post by **palerider** » Mon May 11, 2015 12:48 pm

Gasper62 wrote:Hmmmmmm, that is very interesting that there was a 50% difference between two masks. (more than a little alarming too ! )

you could have gotten a bad one.

adipasqu · Post by **adipasqu** » Mon May 11, 2015 3:27 pm

palerider wrote:
Gasper62 wrote:Hmmmmmm, that is very interesting that there was a 50% difference between two masks. (more than a little alarming too ! )
you could have gotten a bad one.

I'm fairly certain my first one was a bad one. My new one is dead on with the leak rate as published by ResMed. Since I had a great seal (thanks Pad-A Cheek) my leak numbers were still operable and since I loved the fit of the mask and venting over the Quattro FX, I didn't want to be with out it for any length of time.

CplUSMCRetired · Post by **CplUSMCRetired** » Tue Apr 10, 2018 7:38 pm

The issue I had with the Airfit is that the elbow connection was not sturdy. So when I would lay on my stomach, it would pop off a little without disconnecting. So if you have excessive air coming from that general area, it is likely that the elbow isn't fully seated into your mask. When it wasnt cockeyed, the air venting was almost silent... when not though, it's very loud.

Does the Airfit F10 vent excessively ?

Does the Airfit F10 vent excessively ?

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