Here is an inventory data flow model diagram available to download for free. If you open it with the eddx format, you will see the data flow model symbol library on the left of the canvas. Simply drag and drop any shape you want to finish your diagram.
Data flow chart templates sharing community allows you to share your great data flow diagrams with others. Meanwhile, you can also download any diagram you need freely. All templates are available to edit and redesign in the way you want.