How to use this graph:

This graph is used to predict the gallons per minute (gpm) of wort you'll be able to chill from boiling down to 68oF (ideal fermentation start temp) using water from your garden hose as the cooling media.

1) Measure the cooling water flow rate in your brewery using a bucket of known volume and a stop-watch (gal/min).  Then measure the cooling water temperature using an accurate thermometer.

2) Choose either the blue (5.0 gpm), cyan (3.0 gpm), or green (2.0 gpm) line that best matches your cooling water flow rate. If your flow lies between these lines, it is acceptable to interpolate between them.

3) Go to the point on the Y axis labeled "Cooling Water Temp (F)" to your cooling water temperature measured in step (1).

4) Draw a horizontal line to intersect the cooling water flow rate line you selected previously (Blue, Cyan or Green) in step (2)

5) Draw a vertical line at the intersection point down to the X axis labeled "Wort Flow (gpm) and read the wort chill flow rate you'll get at your brewery!

Example: If you have 58F cooling water and 5 GPM of flow, draw a horizontal line  (see dark line in graph above) at 58F over to the blue line.  Draw a vertical line (see dark line in graph above) from the intersection point down to the X-axis and read 2.0 GPM.

That's it!