written by Albrecht Truter

I'm frequently asked how much sample we require for laser diffraction particle size analysis. I suspect  in many cases I'm asked simply because my customer suspects they might have to little sample for the test!

In any case for a dry sample we ask for at least a couple of grams of sample (about a teaspoon).  For realy fine material ( less than 100 um) we can even measure 0.2 g of sample although it is not ideal. Of course if the size distribution starts at  0.5 um and stretches to 2- 3 mm we prefer a teaspoon size sample !

We are also frequently asked to measure water samples from clean  drinking water to turbid raw or even waste water.

In the case of drinking or potable water, particle size analysis using laser diffraction is simply not possible. Laser diffraction is designed to measure a material or sample and is not a trace analysis technique. In this case particle counting is a good option. a Particle counter is designed to count the number of particles in a liquid (or even air, see our air particle counters). Particle counting is a trace analysis technique . Many years ago I was told about the three C's namely contamination ,concentration or count. If the three C's are involved consider a liquid particle counter test for your sample. We now offer this test for oil or water samples.

Back to laser diffraction and dirty water samples.  It is possible to measure most realy turbid or dirty water samples with laser diffraction. We prefer a sold content of 10 g/l.  

In the case of cloudy water samples ( normally too "dirty" for particle counters) we can simply try to use laser diffraction. We follow an simple policy,if we cannot measure your sample, we will not charge you for it.

Hopefully this short note clears it up for many people . If not get in touch and we will gladly assist !