A 250-ft-high office building has a 6-in. diameter steel standpipe and a 100-ft long 2-&-in. diameter fire hose on each floor. The nearest fireplug is 100 ft away from the standpipe’s ground connection. The firefighters connect a 6-in. diameter, 50-ft long hose from the fireplug to the pump on the fire truck and a 4-in. diameter, 50-ft long fire hose from the fire-truck pump to the ground standpipe connection. The National Fire Protection Association (NFPA) code requires that a minimum pressure of 65 psig be maintained at the connection of the 2 -&-in. diameter fire hose on each floor while maintaining a flow rate of 500 gpm through the fire hose. What pressure rise must the pump on the fire engine provide to satisfy the NFPA requirements for this building? The fire-hydrant water pressure is 80 psig, and the water temperature is 70°P’
In many piping situations, pipe diameter is the most important variable. The remainder of the problems in this chapter feature pipe diameter as the unknown. Each problem, whether dominated by pipe length, elevation difference, or pressure difference, requires the selection of an appropriate diameter, sometimes with rather scant information. However, because of the dominant role played by the diameter, a parametric study of pump increase in head versus pipe diameter will demonstrate a relatively small diameter range as feasible.