Due to the current need for facial protection, measuring setups are necessary to determine the safety of a large variety of facial masks. This report describes the building of a dry particle test setup. This test measures the filtering capabilities of the mask of different particle sizes, namely 0.3 um to 10 um using a particle counter or fit tester as a particle counter. For the rest of this work, the fit test or dedicated particle counter will be referred to as particle counter.
Equipment and Parts Required to Build and Produce
- Particle counter (e.g. SOLAIR 3100) or fit test (TSI PortaCount) (tubing and other equipment are shipped with the respective devices).
- 3D Printer
- PLA or other filament
- Lathe (optional)
- Laser cutting machine
- Plexi-glass (200x200mm)
- CAD program (e.g. Solidworks)
- M6 nuts (14)
- M6 washers(14)
- M6 thread (3x 10 cm)
- Pipe (Outer diameter depends on particle counting device used since they come with different size tubes)
- Sealing ring
- Standing nubs (optional but recommended for stability)
Producing the Parts of the Setup
The CAD files are available for all the components as well as their assembly in accordance with the following illustration:
In theory, all these components can be 3D printed and used, with the exception of the nuts and threaded rods. However, for the baseplate and compression lid plexi-glass is recommended because of its stiffness. Furthermore, the rubber footing adds grip to the setup which makes the setup easier to work with.
The pipe, particle chamber and compression lid, when 3D printed with PLA, will likely leak. Therefore it is recommended to use steel or rubber for the pipes, aluminium for the particle chamber (which can be lathed or purchased). It is also possible to seal the 3D printed parts with a resin. For the compression lid one can use plexi-glass. The sealing ring has to be made out of rubber or rubbery airtight material.
About the Setup
The setup consists mainly of 2 parts, the particle counter and the particle chamber setup illustrated above. These must be connected using a tube, via the outlet pipe of the particle chamber and into the inlet on top of the SOLAIR 3100. Preferably, this tube should be an anti-static tube such that little to no particles stick to the tube. Such a tube is provided with the SOLAIR 3100. On top of the particle chamber a mask can be placed which is then pressed against the O-ring using the plexi-glass lid. This plexi-glass lid can be fastened using the nuts and knob. Note that the height can be adjusted to fit and secure the particular mask in question, only make sure that the plexi-glass does not break by raising and lowering the nuts. The data is printed by the SOLAIR 3100.
Please view the following pictures for a clear illustration of the setup using a SOLAIR 3100 particle counter. This counter can be replaced with a fit test particle counter.