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Design Handbook on Animal Research Facilities Using Static Micro isolators 
4J.4 Verification Using the TSI-IFA Hot Wire Anemometer 
Air velocity fluctuations were measured using a fast response TSI IF A- 100 anemometer. The 
IF A- 100 is capable of measuring air velocity fluctuations up to 5,000 Hz. Due to the turbulence 
nature of the air diffuser, most of the energy of the airflow is carried by the low frequency (less 
than 5 Hz) flows. Figures 4.1.10, 4.1.11, and 4.1.12 show the airflow fluctuation patterns using 
sampling frequency 100, 40, and 20 Hz, respectively, within 2.5 second sampling period. 
Statistical comparisons of these three sampling frequencies are show in table 4.1.01. 
Table 4.1,01 Statistics of air velocity fluctuations at sampling frequencies 100, 40, and 20 Hz . 
Sampling Frequency 
100 Hz 
40 Hz 
20 Hz 
Mean air velocity (fpm) 
263.1 
264.3 
265.5 
Turbulence intensity 
0.123 
0.124 
0.129 
The differences in mean air velocity were less than 0.5 percent between 100 Hz and 40 Hz; less 
than 1 percent between 100 Hz and 20 Hz; and less than 0.5 between 40 Hz and 20 Hz. The 
differences in turbulence intensity were 0.8 percent between 100 Hz and 40 Hz; 4.9 percent 
between 100 Hz and 20 Hz; and 4 percent between 40 Hz and 20 Hz. In this project, sampling 
frequency of 40 Hz was used. 
