Breathing Air Pump Filter?

Are you positive that it's never been used? For my remote air, I simply use a stack of ten fans, with paper crosses in between each one, all inside a cardboard sleeve. Works well, and produces quite adequate flow even at the end of long lengths of 1" tube. And no possibility of nasties in the air. Low power and quiet too.

What are the "paper crosses" for?

If you put two fans next to each other, then the total pressure created by them is nearly the same as one fan. This is due to the air coming out of the fan rotating in the same direction as the fan, so the next set of fanblades just stalls.

If however you place card dividers in the airflow, in the form of crosses, so that the air from each fan blows through them, then it is stopped from rotating, and each fan adds to the total pressure.

Yes, I opened the box. I bought several of them at an auction, all in the original shipping box from the manufacturer.

Interesting.

I guess this is also seen in various forms of machinery like turbofan engines and pumps, where there are stacks of interleaved rotating and stationary fan blades. The air from each stage is re-directed in the opposite rotation direction I suppose.

Jim

What is the general design of the pump? Is it just a shop-vac type thing? If so, there is little problem. Oil sealed pumps or oil lubricated pumps of any sort are troublesome, as you've got to ensure no oil gets into the breathing gas. Any pump that involves oil lubrication and high pressure can in principle generate CO. This can also happen if the oil mist/vapour is in the inlet airstream.

I'm jumping in cause I've used the Gast pumps in machines. I think they are dry carbon vane pumps. They are noisy as hell and I don't have a clue as to whether they are "man-rated" to supply breathing air.

Gast also makes diaphragm-type pumps. Those would be a better choice than a carbon vane pump. The second would be almost the worst choice.

Jim

Yes. There are probably better shapes to use than the cross, but it's easy to make.

GAST does make rototy vane pumps for breathing purposes. We used them for "medical air" in retrofitting a Beech King Air to an air ambulence (many years ago). Of course we had filters and traps on the input and output. Check page 4 of: