Styrofoam Beads Sensing


Thread Starter



I have a question regarding sensors.

We have to install a sensor that will detect the flow of Styrofoam beads (diameter 2-3mm) in a 8 inch galvanized ventilation pipe. No need for analog signals because we only want to know if they are beads going through the pipe.

I've been having different answers from different sensor distributors and can't seem to find a good solution.

I'm thinking an ultrasonic digital sensor will do the trick but I would like to have other inputs. What do you guys think?

As I understand it, the ultrasonic technology picks up 'scrapping' noise from solid material rubbing against metallic piping.

Whether styrofoam generates that kind of noise, who knows?

Doesn't the distributor/rep have a demo unit you can connect and see if there's sufficient signal to give you a flow/noflow state?

Gerald Beaudoin

I'm going to think really basic about a small "paddle/piece of wire" on the end of a micro switch arm?
How is the material moving through the pipe? Is it free-falling, pneumatic conveyor or somehow forced from one end of pipe? If its pneumatic conveyor, then ultrasonic sensor can not be used, since the moving air "blows away" the sound waves and the signal won't be any good. If this is the case, then optical sensor would be most appropriate. Any other case, the ultrasonic sensor will probably work just fine.