Hello Terry Lingle,

Fluid flow detection has been around a long time. Most detection is done with a paddle wheel type of device. The following web site has products which detect fluid flow. http://www.chemline.com/digiflowproducts.htm.

They also have a good information page at the following web page.
http://www.chemline.com/PDF%20Fil...roPage.PDF

I have been using these devices in gas station dispensers for years and they are very effective.

A search on www.google.com for "paddle wheel" gave the following 15,400 results.
The results can be seen at the following web address.

http://www.google.com/search?as...afe=images

Good luck,

Charles Bannister