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Ventilation Design Handbook on Animal Research Facilities Using Static Microisolators 
The CFD simulations were only solved directly for the concentration of CO 2 . Concentrations of 
NH3 are calculated in the post-processing stage of the quantitative analysis using a factor derived 
from the relative generation of CO 2 and NH3. This factor varies according to the relative 
humidity in the cages and the number of days that have elapsed since the cage bedding was 
changed. 
Vector 
1.500 
1.286 
1.071 
.857 
.643 
.429 
.214 
.000 
Figure 2.24 Velocity Vectors (m/s) 
The vectors are plotted so that the tail of the arrow is at the point where the value was calculated 
and points in the direction of air movement. In 2-D planar views the length of the arrow indicates 
the 2-D magnitude of the velocity (the arrow is projected onto the plane of viewing) when 
compared to a reference vector, while the color indicates the overall magnitude of air speed at the 
tail. 
To aid analysis, the color scales are set the same on different diagrams as much as possible. For 
example, the temperature scale runs from 18.0 °C to 25 °C (64.4 °F to 77.0 °F). The concentration 
scale runs from 0.0 to 5 g/kg or from 0.0 to 0.5g/kg depending on whether the plane is concerned 
with showing the concentrations inside the cages or outside in the room, where the 
concentrations are generally much lower. Values outside the range will appear as blank areas in 
the solid fill or a region with no vectors. If lower than the scale, the area is surrounded by colors 
at the bottom of the range and above by colors at the top of the range. 
