Level sensor for dust particles

Thread Starter


Joined Jan 2, 2013
Hello everyone,

I am in requirement of a level sensor that can detect the level of dust in a tank. I tried on float level and capacitive sensors but they are less effective on dirt granules. So please suggest me a suitable sensor.

Thanks in Advance


Joined Nov 23, 2012
Generally, particulates in air or liquids (dust and smoke) can be measured by placing an IR emitter (LED) at a right angle to an IR phototransistor. The transistor lets more curren through when particles are present and cause the IR light to get reflected into the phototransistor.

Google a phototransistor circuit. You can add a comparitor to set a threshold on/off output (ok vs too high). or use an op amp or transistor to get an analog reading. In the analog case, you are mesuring reflected surface area, not number of particles. This sensor cannot differentiate between many small particles or a smaller number of large particles if total surface area is similar. Particle shape will influence it too.

You may have to clean the parts regularly since dust can settle and skew results.


Joined Sep 9, 2010
That's a turbidity meter, which will work. I suppose a particle that is highly absorbent, and doesn't reflect the IR beam, could fool it. Another approach would be a straight beam, like a spectrophotometer or a garage door safety sensor. You would measure the intensity of the received beam. In the lab, you would usually use a dual beam with one not obstructed, to take out any variations in the light intensity and such.

Designing instrumentation for industrial use is not a trivial exercise. I encourage you to research the existing commercial devices before you try to make your own. I can imagine there are safety issues involved, and these must take priority.


Joined Dec 19, 2007
Google: dry powder bulk level sensor

Are you looking for a continuous measurement of level, or just full and empty levels?