Posted by 18ms on .
if a pump discharges 75 gpm of water whose specific weight is 61.5 lb/ft^3(g=31.95fps^2). find a) the mass flow rate in lb/min, and b) and total time required to fill a vertical cylinder tank 10ft in diameter and 12ft high.

thermodynamics 
drwls,
(1) There are 7.48 ft^3 in a gallon. Therefore the volume flow rate can be expressed as 75 gallon/min/7.48 gal/ft^3 = 10.03 ft^3/min
Multiply that by the density of water, 62.4 lbm/ft^3, and you get 626 lbm/min.
(lbm stands for pounds mass; the preferred mass unit in the British system is slugs)
(2) Time = Volume/Flow rate
= (pi/4)*D^2*L/10.03 ft^3/min
= 94.0 minutes 
thermodynamics 
Jerwin,
is there really a 7.48ft^3 in a gallon?...
isn't it 0.133681?