User's Guide

Chapter 3. Using Your APS3
3.20
To change the averaging interval:
• In the Display Controls, under Averaging Interval, choose the interval in seconds,
minutes, or hours for averaging the particle measurements. The new setting takes
effect immediately.
Figure 3.20: Horizontal Scale
For example, you know the airflow through the APS device is 0.1 cubic feet per minute but you
want to average the particle count over one cubic foot of air. You can determine the length of
time the APS device needs to run using the following formula:
Using the formula you know the APS device needs to run for 10 minutes to process one cubic
foot of air.
Measurement Accuracy
The APS device’s accuracy is based on particle density measurements using an averaging interval
of ten minutes. The shorter the averaging interval, the accuracy of numeric measurements
is degraded while longer averaging intervals will have increased accuracy of the numeric
measurements.
1 cu ft.
= 10 minutes
0.1 cu ft. per minute
Averaging Interval