I designed an accumulator for an air quality monitor for AethLabs. The requirements for this component include tight tolerances (for packaging), reliable functionality, and being as leak-proof as possible. These design constraints led to a challenging adventure that took me through research, testing, and over a dozen iterations. 

The original concept was brought to me to be made of PVC and adhesive. Due to the need for internal geometry (for pulsation damping) and precise packaging, I opted to explore 3D printing. This would also make production significantly easier for assembly technicians. The greatest challenge was establishing a reliable method for airtightness within the part. I designed 3D printed barb features and finely tuned 3D print settings to create this accumulator with <0.1 ml/min leakage. 

Test Methods

As this component needed to be reliable for the first round of production, I thoroughly tested it in each design/iteration. Testing was performed to locate, quantify, and characterize leaks by doing in/out flow rate comparisons and performing bubble leak tests. Pulling from my experience doing composites for Baja SAE, I utilized tacky tape (as seen in the top image) to isolate leak locations in each iteration. 

Once internal packaging was finalized, I designed the production version (bottom image) using the same design aspects developed during testing. 

This in-line condensation trap fits into an exhaust line from our production air quality testing. As part of this testing involves warm dirty air (unspecific due to my signed NDA), H2O condensed along the walls of the tubing, leading back down the line into another water trap. To increase this storage of condensed liquid and reduce maintenance, I designed and tested this watertight trap, which can be easily installed and removed due to its functioning 3D printed barbs. 

Due to the level of contaminants in the exhausted air, PETG was chosen for its chemical and water resistance. The part was tested by filling it with water and seeing if it would leak over several days in the production testing environment (it did not).