Important note about the PEMS data processing spreadsheets: The zero flow and full flow pressure readings are taken from the raw data file and no longer need to be recorded on the data sheet. Only the Magnahelic gauge reading needs to be recorded. In order to capture a zero flow reading, let the PEMS run for the first minute with the fan off. The full flow pressure reading is taken during the background period, which starts after 4 minutes of run time (changed from 2 minutes). Turn on the fan between 1 and 4 minutes of run time.
Important note about IAP Meter data processing spreadsheets: These spreadsheets use the real background for the calculations (not the average of the real background & the minimum value). If there is a large temperature increase during the test (10 deg C or more), then the CO baseline will drift noticably. The baseline can be easily straightened out by adding a CO temperature compensation factor on the Calibrations sheet, cell D19. It is best to take a background in clean air before & after the test. Then it is easy to see how much temperature compensation to add. The compensation factor may be negative. It is also a good idea to turn the meter on & let it run for at least 5 minutes before starting the background period, because there is a relatively large internal temperature change when the meter is first turned on.
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