Based on the given principles for the reasonable working range of an axial flow ventilator, and the operating point shown in Table 9-4-2, it can be concluded that the selected fan is within the acceptable range. The fan model chosen is 62A14-11 Mining axial flow fan No.24.
The upper limit principle specifies that the maximum wind pressure value should be 0.9 times less than the value to the right of the “hump.” Looking at Table 9-4-2, we see that the maximum wind pressure value is 3,200 Pa, which appears to be slightly to the right of the “hump.” Therefore, selecting a fan with a maximum wind pressure rating of at least 2,880 Pa (0.9*3,200) would satisfy this criterion.
The lower limit principle requires that the ventilation fan operating efficiency must not be less than 0.6. Again referring to Table 9-4-2, we find that all four fans listed have an efficiency greater than or equal to this minimum requirement.
The left and right limits specify minimum and maximum values for blade installation angle θ for each impeller class. Without additional information regarding specific requirements for this application, we cannot definitively say whether these limits are met by any particular fan. However, since no mention was made of issues related to these limits in selecting a suitable fan from Table 9-4-2, it seems likely that they were not problematic in this case.
Overall, based on available information and following accepted principles for selecting axial flow fans, it appears reasonable to select model 62A14-11 Mining axial flow fan No.24 as a suitable option for this application.
