Hello all, my name is Dan, and yes I'm a newbie. I read over other newbie posts and see folks here have patients and do not mind sharing info so I'm posting this project or "idea" if you will. I work at a processing plant that extrudes polypropylene pellet. the problem is when the pellet gets wet it shuts down the process. when I search for a detection system for this problem I find sesors and advice on moisture content of the pellet but I'm after something that will detect moisture or water on the surface of the pellet as it is pulled into the building thru a vacuum conveying system. I would like to be able to build a device with a probe that can be inserted in line and detect water on the surface of the pellet and possible sound an alarm. Now, where to start. Any thoughts would be greatly appreciated. I am new to all this but want to learn. Thanks, Dan

 

Hello,

It looks like you are looking for a hygrometer (waterdamp).
http://en.wikipedia.org/wiki/Hygrometer
What is the amount of water allowed in the air around the pellets?

Bertus

 

Well, i dont want to sound silly, but at the moment we are using the "feels wet" test!!Normally the pellet feels dry but when we have an issue you can run the pellet over your hand and see the water on your hand. We do not have any test equipment or bench mark other than if its actually wet.

 

I guess what I'm looking for is something that will detect the presence of water rather than humidity, if that makes sense!

 

Hi!
I think the best solution for your case would be Wireless Relative Humidity Data Logger. The product is available commercially. All you will have to do, will be to interface this data logger to your existing control/supervisory system and then out put the desired control signal whether alarm or any interlock. One prospective link might be :

http://www.mesalabs.com/products-services/datatrace/MPIII-relative-humidity-data-logger.html

 

I'd consider one of those RF moisture detectors they use to measure moisture in walls or concrete floor. It requires no contact or movement of water to the sensor. And somehow it can differentiate water from other building materials. Not sure about plastic.

 

Hello,

I think you could use a rain sensor schematic like this:
http://circuitdiagram-schematic.com/116/simple-rain-alarm-circuit-using-ne-555/

Bertus