Finding a Bottom Section: Divide

Cover a bottom section. The top is divided by the section that is left.

Detention TimeTap a section to cover the quantity you want to find.

What remainsTime = Volume ÷ Flow

Now the unknown is below the line. Cover Time: Volume is left above Flow, so divide the top by the section that is left.

Time = Volume ÷ Flow

120,000 gal ÷ 1,000 gal/min = 120 min

Tap Volume, then Flow, on the wheel. The formula changes with the section you cover; the wheel stays the same.