Tactically_Fat t1_jcgf4ya wrote on March 16, 2023 at 5:22 PM

Reply to comment by hazpat in Open-source tool from MIT’s Senseable City Lab lets people check air quality, cheaply. by chrisdh79

Need to be able to audit flow.

And flow is related to temperature and pressure.

Agreed that a simple leak check can be peformed with a HEPA filter.

PM samplers that can/have met Federal Equivalency Methods status are all able to be calibrated to atmospheric conditions as well as having these things audited / verified.

A lot of this is done so that the data generated can be defensible should the need arise.

hazpat t1_jcghwce wrote on March 16, 2023 at 5:39 PM

Flow meters are usualy built in and auto adjust. Checking flow with a rotometer is fast and simple.

Most meters operate under factory calibration factors that are acceptable under most conditions. You can, but are not required by any regs, to set user calibration factors based on local conditions. This is a very tedious process that you don't typically see people do unless they are in abnormal conditions like constant fog or whatever. On my meters temp and pressure sensors are built in, no idea about the purple, but I would trust the particulate data if it passed a flow and zero check.