One Way Air Valve (Non-return valve - Check Valve)

I designed this for the air scrubbing and extraction system I made for my printers, some of which now share air ducting. Therefore, I needed to make sure air is not pushed back through the HEPA filters of print chambers that are not in use when the extraction for that printer is turned off. I really don’t want filtered waste etc. spewing all sorts of nasty dust particles back into the print chambers and out into the room!

The photographs here show a first draft with a 0.3mm steel wire supporting the flap. The translucent version clearly shows the flap moving in use. This acts as reassurance in daily use. Also shown is one that is now in use within the chamber of a CR10 Smart Pro.

This non-return valve is a one-way push-fit air gate or valve for 38/42mm plastic pipe (the pipe I used has a 41.6mm outside diameter). However, within limits, this can be rescaled to fit a similar sized pipe if the gate is also resized to fit.

Use a 0.4-0.8mm straight wire to hold the gate in place (or a similar loose-fit straight rod).

Print as oriented without support at 0.18 or 0.2mm layer height and 2-3 walls in PETG or other materials. (If using translucent filament for the box and red or similar for the gate, you should be able to see the gate activate when the extraction is on/off.)

The gate is designed to be 0.4mm thick. When printing, the flap should be two 0.2mm layers including the base layer, or you can make it a little thinner as long as it is rigid enough not to bend or fold with any backdraft or reverse air flow.

Although this one-way air valve is not completely airtight, it should restrict backflow through HEPA filters etc. back into a print chamber. Mount horizontally for best results.