Ventilators Hackshops

PJ Many thanks.
I am in pre-emptive isolation though.
Others can get on and make them too! The active ingredient is Zeolite granules that can be purchased via Ebay. It is readily available, as it is used for filtering aquarium water.
If my simple system works it may not have a high percentage oxygen output. If someone wants to copy the way the conventional machines work, with solenoid valves, microcontroller etc, that would be great too.
Also, how can we measure the percentage oxygen? The meters commonly available seem only to go up to 30%. If someone could have a look for one that goes higher that would be great. Initially the simplest test is that oxygen re-lights a glowing splint/match/candle.

Thanks Hugo. I’m trying social distancing at the moment but will probably ramp up soon… Any idea how much Zeolite would be needed for a single unit? Does it run out (get chemically depleted) in normal use? Or is it more of a physical filter, and if so does it need cleaning? Or does the exhaust air flow keep it working? Oh! and how much did you pay for yours? Questions Questions…

Another open ventilator project:

which links in turn to Open Source Ventilator (OSV) Ireland

(via Jeff Allen on mastodon)

I don’t know how much Zeolite granules precisely, but guessing from the size of the cylindrical containers in the video, a 2 kg bag of it looks about right. It is not particularly expensive.
I have two tin cans prepared as the Zeolite container. They will be soldered end to end. Punched a small hole in the end of one of them, which will be the oxygen delivery outlet. Have made a tube from sheet tinned steel, (from another tin can) to fit the inside of garden hose. The hose is for oxygen delivery. Punched two holes in the end of the other tin can. One with a tube to fit the tyre inflater. The other to fit my thumb! This latter will be the nitrogen outlet.
And I will put a disk of sponge into the ends of each tin can, to prevent the granules escaping.
This is about as basic as I can think to do it. Using a small orifice as the outlet I hope will mean that a spring loaded valve is not needed. We can add complication later, if needed. The hole can be made bigger if needed.
And now I am stuck because I have mislaid my reel of solder.
(Did you ever read “Zen and the Art of Motorcycle Maintenance”? I am now in a state of stuckness.)

I bought this, which is just over £7 for 2 kg:

I don’t believe it runs out. It is a physical process - the nitrogen gets attracted preferentially into very small pores on the surface. It should not be allowed to get wet though, as that then blocks the pores. The effect of compressing the air will warm it up a little anyway, so hopefully if it were damp it would soon dry out.

Thanks Hugo. Will get a couple of tins. I started reading Zen etc … but as an aspirant biker there was too much Zen and not enough motorcycle for me. But I did hear a radio version some time ago so that’s a tick. Of course you can’t get real solder anymore, just the safe stuff that doesn’t work as well as Old Toxic. Good luck with your build. Will be in touch later if I manage to get the parts and do not get distracted by all the other things that I think I should be doing…

Well I found the reel of solder and so became un-stuck.
Have assembled the Zeolite container using two tin cans. Made a tube (using sheet metal from a third tin) suitable to attach to a tyre inflator, and another tube suitable to fit snugly to the inside of a length of garden hose - for the delivery outlet. Two holes in the end of one tin can (one for the compressed air inlet, the other for the nitrogen exhaust. These holes do not need to be all that big. say 3mm dia. (will optimise later). A very small orifice at the end of the other can.
Fitted a sponge disk into the inside of each can, and pushed it to the further end. This is to stop the Zeolite granules escaping. Filled up both cans with granules. Using card (from a cornflakes packet) covered the end of one can, inverted it over the other, removed the card, and taped them together. Then gradually undoing the tape and soldering around the rims. Important to ensure there are no gaps - even small gaps are a problem.
The orifice is a little tricky, particularly as I have no very small drills. Punched a hole with a small screwdriver, then filled it in with solder. I do have some pottery tools, one of which is a V shaped blade. Then gradually carved into the solder, making a V shaped hole. Unfortunately I have over-done it, and the orifice is too big, so with the pump that I have the pressure does not go over 1.5 bar. Will have another go tomorrow.
I had a go with a match to see whether oxygen is being produced. Inconclusive at the moment. The amount of air coming out of the orifice is blowing out a lighted match, rather than re-lighting a glowing match.
It may be that 2 bar will be the limit anyway - the ends of the tin cans bend out alarmingly!
ZAMM is available as an audio book:

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If you’re succeeding in enriching the air (by taking out nitrogen) then, for example, a candle in a bell jar should burn brighter or longer in the enriched air.

As the aim is to alleviate distress and prolong life in the case that conventional medical help isn’t available, even some partial increase in oxygen levels might be a benefit. (This kind of homebrew device could, I think, only be used in the home, as the medical profession are surely going to use only approved devices. Unless we see evidence from Italy to the contrary?)

Edit: some informed commentary and further links in this discussion:

There’s an overview here of the need for assistance in breathing and the various ways of providing it, with their pros and cons:

Thanks for this Ed. It is just the sort of thing I have been (unsuccessfully) looking for.