CPAP Hose Dryer: MVP Overview

For all the usual reasons, we’re now confronted with the need to dry a freshly washed CPAP hose:

CPAP Dryer - water droplets in hose
CPAP Dryer – water droplets in hose

Those droplets might not seem like much, but I am reliably informed they produce over-humid air and sprinkle when they migrate into the mask during the night.

Commercial drying machines are available, but seem grossly overqualified and require proprietary foam filters. I wondered if simply pulling air through the hose for a few hours would work:

CPAP Dryer - dried hose
CPAP Dryer – dried hose

Why, yes, it does.

That test took two hours and another with a different hose required about five, but simply “hanging the hose up to dry” consistently produced poor results after three days, so we count a few hours as a win.

I cut the first minimally viable prototype CPAP Hose Dryer from MDF:

CPAP Dryer - overview
CPAP Dryer – overview

Stipulated: MDF is absolutely the wrong material for an air-handling project, because laser-cut MDF stinketh unto high heaven. This was the first pass using cheap material to see how well, if at all, the idea worked.

The CPAP hose goes between the fittings on the bottle and box, with air entering the bottle through a hole drilled in what was its bottom:

CPAP Dryer - filter bottle cutout
CPAP Dryer – filter bottle cutout

An air filter seemed like a Good Idea™, if only to keep ordinary room fuzz out of the bottle and hose. In this Third Pandemic Year, I could simply pull a least-favorite N95 mask from the stockpile and fit a clamp ring around it:

CPAP Dryer - filter clamp installed
CPAP Dryer – filter clamp installed

The motivation for pulling air through the tube, rather than pushing it, came when I realized I could build a much cleaner intake structure by starting with an ordinary HDPE bottle than I could possibly assemble from random parts.

So the fan in the box pulls air through the fitting on the side of the box and blows it out the swirl on top:

CPAP Dryer - fan box
CPAP Dryer – fan box

The box contains a coaxial power jack, the switch, and an 80 mm fan extricated from the Box o’ MostlyFans. I briefly considered an LED, but it’s obvious when the fan runs. The box and swirl cutting patterns come from the invaluable festi.info.

The two slots give the bottle somewhere to stand while idle. In use, the hose is sufficiently unwieldy to require standing the bottle wherever it wants to be, rather than insisting on putting it anywhere in particular.

More details to follow …

10 thoughts on “CPAP Hose Dryer: MVP Overview

    1. Yup, that’s the intended target. My box has a few other odds & ends in it, so I couldn’t pass up the opportunity.

      Their landing page suggests a sports bra will proper attire for any occasion, from flower arranging to cooking. Not quite NSFW, but leaves little to the imagination.

  1. Don’t you already have a (very expensive) device for running air through that particular hose as its one job? That’s what I use…

    1. It shuts off when the mask isn’t in place: continuous product improvement in full effect!

      There may be a configuration setting turning it into a dumb blower, but I have sworn a mighty oath on the bones of my ancestors to not fiddle with its “clinician” controls until we get unstuck from its part of the medical-industrial complex.

      Further, deponent sayeth not.

      1. My first CPAP machine was through insurance, though when it hit end of life, I bought the replacement through a regional distributor. No insurance, and at the time, no prescription was needed. When that one hit EOL, I bought two replacements (we’re a long way from DME outlets and Murphy is a stone-cold SOB) from the same outfit. All these either came with the clinician manual, or I was able to download such. I had my regular doctor prescribe the last machine(s); I wrote what I needed and he signed it. Worked like a charm. (I’ve heard that dentists can prescribe CPAP machines. Haven’t seen a lung doctor since 1998.)

        The distributor is CPAPman dot com, out of Washington state. I got the manuals through the Apnea board, a very good source of information. They also have support for the OSCAR data program.

        http://www.apneaboard.com/

        Can’t remember if the second generation machine is still in the box-o-stuff. The first generation got a DIY bearing replacement and the reset fan spacing made a better siren than blower. Somebody forgot to take detailed measurements, and there are no stops on the motor/fan shaft… Oops.

        I really should clean my hose more often. I swap filters 2X per month and use a hose-cozy to help the hose heater. The silicone insert gets cleaned daily; that seems to be sufficient for the plastic to last a long time. (Maybe 5 years on this one, so far.)

        1. We installed OSCAR, popped a suitable SD Card (*) in the slot, and have been poring over graphs ever since: we are numerically inclined. [grin]

          All the cleaning & sanitizing & fiddling reminds me why we don’t have pets …

          (*) Dunno why I had one with an ext2 filesystem, but the machine spat it out instead of auto-formatting it.

          1. Off the shelf SD cards work OK, though I found there is a finite limit on the number of times the plastic fingers survive insertion. I’ll download to OSCAR once a week; if memory serves, the detailed data gets overwritten after 9 days. I ran across the 4(!) G SD card in the Box-o-cards and am using it. Some of the cards just fail after a year or so, and these are ostensibly good Sandisk cards. Maybe.

            Pet hair? Not a huge problem for us. However, since we’re downwind of many major eruptions over the millennia (and megayears, but who’s counting?), our soil is excellent at generating dust. Sharp, rocky dust. (Dealing with native soil without gloves can make for some interesting splinters from tiny obsidian shards. Whee.) So, pet dander/shed hair is the least of our dust issues. Though we once had a border collie who could get shed hair on top of the shelf above the shower enclosure… The current dog sheds on carpet in season.

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