=+12-10. A duct system has been designed to have 3.0 in. wg total pressure loss. It is necessary to use an elbow at the fan outlet that causes a system effect factor of 0.3 in. wg. The fan inlet also has an elbow with a system effect factor of 0.20 in. wg.

(a) What total pressure should the fan for this system produce to circulate the desired amount of air?

(b) Sketch the system and fan char-

acteristics with and without the system effect factors.

(c) The design volume flow rate is 15.000 cfm. Using Fig. 12-9, estimate the resulting flow rate when the system effect factors are not used.