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(a) When the system was started, measurements were made and a flow rate of 10,000 cfm and total pressure of 2.0 in. wg were observed. Explain the probable cause of the discrepancy. (b)

At another time, after the problem of part

(a) was corrected, a flow rate of 12,000 cfm and a total pressure of 5.0 in. wg was observed. Explain the possible problem in this case.

(c) Sev-

cral years later, after the problem of part

(b) was solved, measurements show a flow rate of 12,500 cfm and a total pressure of 4.0 in. wg. Explain the probable cause of the decreased flow rate.