The above process flow diagram or PFD was drawn with the RFFlow software.

If you haven't already done so, first download the free trial version of RFFlow. It will allow you to open any diagram and make modifications.

Once RFFlow is installed, you can open the above drawing in RFFlow by clicking on process-flow-diagram-2.flo. From there you can zoom in, edit, and print this sample diagram. It is often easier to modify an existing diagram than to draw it from scratch.

To draw this diagram without downloading it, run RFFlow, click on the More Shapes button , scroll and open the Industrial Objects folder, click a stencil and click the Add Stencil button.