In the calibration jar method, how is the flow rate in gallons per minute (gpm) calculated?

In the calibration jar method, how is the flow rate in gallons per minute (gpm) calculated?

• A. 15 Divided by S, Where S Is Seconds to Fill a 1-Quart Jar
• B. S Divided by 15
• C. 60 Divided by S
• D. S Divided by 60

Answer: (A)

In this method you measure how long it takes to fill a known volume, then convert that time to minutes and divide the volume by that time. The jar is 1 quart, which is 0.25 gallon. If S is the number of seconds to fill the jar, the time in minutes is S/60. The flow rate in gallons per minute is volume ÷ time, so 0.25 ÷ (S/60) = 0.25 × 60 / S = 15 / S. So the flow rate is 15 divided by the number of seconds to fill the jar. For example, if it takes 10 seconds, the flow rate is 15/10 = 1.5 gpm. The other options mis-handle the time units or the volume, leading to incorrect results.

In this method you measure how long it takes to fill a known volume, then convert that time to minutes and divide the volume by that time. The jar is 1 quart, which is 0.25 gallon. If S is the number of seconds to fill the jar, the time in minutes is S/60. The flow rate in gallons per minute is volume ÷ time, so 0.25 ÷ (S/60) = 0.25 × 60 / S = 15 / S. So the flow rate is 15 divided by the number of seconds to fill the jar. For example, if it takes 10 seconds, the flow rate is 15/10 = 1.5 gpm. The other options mis-handle the time units or the volume, leading to incorrect results.