If your are looking for a flow metering pump, you might like to check out the web site www.proptec.com
This pump is available up to 12 channels with lots of flexability. It should handle your 50 psi and will meter very viscous and/or "dirty" fluids.
I am looking for a sensor that I can mount on a machine, drive along a tree row, and detect only the tree trunks. There are several mechanical devices that do this, but rely on physical contact to actuate a switch. These systems have many drawbacks. I have used commercial microwave door...