Regarding the number of air changes and fan selection

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I would like to state upfront that I am not an expert in ventilation systems nor am I involved in design work. The content below was prepared as part of the safety assessment for a project recently; in reality, I neither have the necessary qualifications nor the technical skills for this task. Since my supervisor insisted that it be done, I’ve shared it here for everyone’s feedback, especially regarding the parts marked in red. Actually, it’s already installed (of course, not in a proper manner a ); I just need to prove that it was installed correctly. Air change rate in the production workshop: The area of the production site is 30*12=420 m2, and the height of the factory building is 9 m. The factory contains chlorpyrifos (which may produce HCL and H2S), ethanol, triethylamine, cyclohexane, etc.; the toxic or flammable and explosive gases that may be generated all have a relative density greater than 1. In accordance with the provisions of SH3004-1999 (Code for Design of Heating, Ventilation and Air Conditioning in Petrochemical Industries), sections 3.3.3/3.4.2 and Appendix B, the air change rate shall be at least 8 times per hour. Selected fan: 3 explosion-proof axial flow fans of type BT35-11 No. 3.55. Parameters: Rotational speed 2900 r/min, blade angle 30, flow rate 5965 m3/h, total pressure 30.6 mm, total pressure efficiency 0.88, motor power 0.75 kw; explosion-proof motors, model 4—72 No. 2.8; 2 centrifugal fans. Parameters: Rotation speed 2900 r/min, flow rate 2356 m3/h, total pressure 606 Pa, motor power 0.80 kW, Y90S-0(B35). The total exhaust volume of the 5 fans is 22,607 m3/h. According to Appendix B of SH3004-1999 (Code for Design of Heating, Ventilation and Air Conditioning in Petrochemical Industries), when the room height is greater than 6 m, the ventilation volume shall be calculated based on the volume of a room with a height of 6 m or less. Therefore, the room volume is calculated based on a height of 6m. Calculation of air change rate: 22607/(30*12*6) = 10.466 times, which meets the requirement of more than 8 air changes per hour. Fan arrangement: The 3 axial flow fans are all installed above the walkways on the second floor, at the feeding ports of various reaction vessels and separation tanks – locations where toxic or flammable gases are likely to be released – with the fans positioned 0.4 meters above the ceiling. The air inlets of the 2 centrifugal fans are located as follows: the exhaust hood of one fan is situated at the discharge port of the filter on the first floor, while an exhaust hood is placed above the location where the filter cake is collected. The exhaust hood for 1 fan is located above the feed inlet of the reactor on the second floor. The fan is installed outside the north exterior wall of the factory building, with a high exhaust stack being used for the exhaust outlet. This post was last edited by Pseudo Xiao Bao on 2009-3-12 20:55]