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Vemrilatton Design Handbook on Animal Research Facilities Using Static Microisolators 
Further variation in exhaust number and position was investigated in cases 37 to 42, 69 to 75 and 
79 to 84 . Examination of the data for these runs shows no obvious pattern emerging in cage and 
room ventilation. Case 40 (radial supply and four ceiling exhausts in the comers) seems to 
produce particularly low room breathing zone CO 2 and NH 3 concentrations, improving on the 
basecase values. However the other cases with four ceiling exhausts do not seem significantly 
better than the two ceiling exhaust cases. 
3.1.2 Air Change Rate 
Figures 3.23 to 3.28 show comparisons of temperature, CO 2 and NH3 concentrations for both the 
cages and scientists’ breathing zone for airflow rates between 5ACH and 20ACH. The plots 
show results for single density racks (42 cages) parallel to the walls (cases 9, 28-30) and double 
density racks (84 cages, cases 33, 62-64) perpendicular to the walls as well as a variation in 
change station design (84 cages, cases 65-68). All cases have low induction supplies and low 
level exhausts. 
Figure 3.23 Comparison of Mean Cage Temperature (°C) 
