The net positive suction head required (npshr) by a pump may be expressed approximately as parabolic function of volume flow rate. the npshr for a particular pump operating function of volume flow rate. the npshr for particular pump operating at 1800 rpm is given as = h0 + 2 (h0 = 10 ft, a= 7.9 ft/ ). assume the pipe system supplying pump suction consists of a reservoir, whose surface is 22 ft above the pump centerline, a square entrance, 20 ft of 6 in cast-iron pipe, and 90°elbow. calculate the maximum flow rate at 70℉ for which the suction head is sufficient to operate this pump without cavitation.

Ashielded metal arc-welding operation is accomplished in a work cell by a fitter and a welder. the fitter takes 5.5 min to load components into the welding fixture at the beginning of the work cycle, and 1.5 min to unload the completed weldment at the end of the cycle. the total ength of the weld seams 1200 mm, and the travel speed used by the welder averages 300 mm/min. every 600 mm of seam length, the welding stick must be changed, which takes 0.8 min. while the fitter is working, the welder is idle (resting): and while the welder is working the fitter is idle. (a) determine the average arc-on time as a fraction of the work cycle time. (b) how much improvement in arc-on time would result if the welder used flux-cored arc welding (manually operated), given that the spool of weld wire must be changed every 10 weldments, and it takes the welder 5.0 min to accomplish the change? (c) what are the production rates for these two cases (weldments completed per hour)? attach your work and solutions.