Im not the rubber band man sort of guy so when mine started popping out coming up on 90 days of use I was on a mission to figure out why now??
Our house is on wood heat which means dry air and dusty once the fires going. I normally wash that filter every 30 days and change the white around that sometimes sooner.
So I washed the filter for the third time a few days ago. It had never popped out before and nothing has changed. I knew something had to back pressure but ive coughed etc before in the mask and no filter on the floor.
So suddenly im getting about every other day the filter is the floor next morning. So I put it back in started the machine gave a puff on the hose and out it pops. So something changed. Machine is still up to snuff pressure the same etc etc.
I pull the filter and get a new one. Compared to the new ones the original one after three washings and rinses is very stiff.
Put the new softer filter in the machine crank it up puff blow snort into the hose and it never quivers. Sits there solid as a rock.
SOOOOO if your PR machine is popping the sponge filter out try putting in a new one. I dont know if washing stiffens the filter or age but it definitely gets stiff. Stiff it cant give to sudden back pressure and it pops out.
The soft new one seems to absorb any back shocks it gets by giving a bit and stays put. Fixed mine. No more popped filters.
Worth a try if you have that problem:grin:
Oh and no fair laughing at the image of a long haired biker type guy snorting air backwards thru a cpap machine.
It was done in the interest of science after all.