Re: viscosity sensor
D_A_V_E -
I hope you're ready to spend a lot of money to buy a sensor. The ones described in **broken link removed**
cost between $7KUSD and $10KUSD. You can buy a used Viscosimeter for a lot less than that.
You could also use a rotary viscosity sensor, but they aren't small or cheap ( **broken link removed** ).
Depending on what exactly you are trying to do, you can make a viscosimeter by drilling a calibrated hole in the bottom of a cup, and timing the fluid as it drains from the cup. Painters use a tool like that for checking the viscosity of paint before using a paint sprayer. Some labs also use that method for checking to make sure a fluid is within a certain viscosity specification.
College lab students have constructed their own rotary viscosimeters by using a paddlewheel on the shaft of a DC motor and measuring the voltage generated by the motor as the fluid rotates the paddlewheel over a measured time period. Look around on the Internet, and you'll probably find their lab reports describing how it was done.