In the horsepower formula HP = Head x Weight / (33000 x Efficiency), Weight represents which quantity?

In the horsepower formula HP = Head x Weight / (33000 x Efficiency), Weight represents which quantity?

• A. The head in feet
• B. The velocity of the water
• C. The density of the water in lb/gal
• D. The product of flow in gpm and 8.33 lb/gal

Answer: (D)

In this horsepower calculation, the Weight term is the weight flow rate of the liquid—that is, how much weight is moved each minute. You get that by multiplying the flow rate (in gallons per minute) by the fluid’s density (in pounds per gallon). For water, density is about 8.33 lb/gal, so the Weight becomes 8.33 × gpm. This weight-flow rate works with the head (the height the fluid is pumped) and the efficiency to give horsepower via HP = Head × Weight / (33,000 × Efficiency). The head is a height, not a weight; the formula uses the weight flow rate, not velocity or density alone.

In this horsepower calculation, the Weight term is the weight flow rate of the liquid—that is, how much weight is moved each minute. You get that by multiplying the flow rate (in gallons per minute) by the fluid’s density (in pounds per gallon). For water, density is about 8.33 lb/gal, so the Weight becomes 8.33 × gpm. This weight-flow rate works with the head (the height the fluid is pumped) and the efficiency to give horsepower via HP = Head × Weight / (33,000 × Efficiency). The head is a height, not a weight; the formula uses the weight flow rate, not velocity or density alone.