While I am still awaiting the arrival of my new PCBs, I started to think a bit more about how to best position my dust/smoke sensors in a moving air stream (inside and A/C unit or around my fume extractor). While the sensor has a small fan to draw air into, I was concern about how that small fan would do in a fast moving air stream. I sketched out some ideas, scratch my head a bit, and I finally came up with an idea on how I could guide air into and out of the sensor for testing.
Here is Pansonic SN-GCJA5 sensor module, showing its intake and exhaust ports:
I decided to attempt to route air directly to and from the ports, in an inline configuration, providing a separated flow path for the air. Here some 3D images of the design (not the air flow direction marker on the manifold):
And here are some images of the printed part installed on the sensor module:
With the Intake/Exhaust manifold installed, I decided to run a quick test by monitoring the intake and exhaust sides of my fume extractor while generating a bit of smoke while melting some solder. In the following charts, the first 100 samples are take from the intake side of the fume extractor. During this portion of the test, I melted some solder, waited for the concentrations to go down and then melted some more solder. Once the concentrations dropped back to the baseline, I moved the unit to the exhaust side and repeated similar steps. Here are the resulting charts (density and particle counts):
While this is by no means a complete test, it does seem to show that the fume extractor is doing a pretty good job of cutting down the amount of fumes. While the on the intake side of the extractor the density readings hit a hard limit of 2000 in the first peak, while on the exhaust side of the extractor the peaks were 121, 184 and 207 (PM1.0, PM2.5 and PM10), approximately a 90% reduction. (Note: with two sensors, simultaneously sampling, we will be able to get a true intake to exhaust correlation.)
I am continuing to work on the embedded firmware for my dust/smoke datalogger, while awaiting my new PCBs (due early next week).
Thanks for reading along!
Gene