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Sampling technique for stream percent solids (4 replies)

John Koenig
12 months ago
John Koenig 12 months ago

What is the proper way/technique of sampling the percentage of +2mm particles in the slime disposal line of a diamond processing plant. 

  1. Do I take the sample from the bottom of the pipe
  2. Do I take the sample diagonally from the discharge
  3. Do I sample the whole circumference of the discharge

I am trying to stop the arguments on sampling slime in my workplace.

Bill Fraser
12 months ago
Bill Fraser 12 months ago

In sampling any stream the effort is to a get representative sample of the entire stream. This is done by either taking the whole stream part of the time, or part of the stream all of time. Of course when dealing with a very large flow you will often have to take part of the stream part of time. But then it is important to take a true representative cut of the stream, normally by having a cutter move across the stream at a steady rate, and then working the sample down further.

12 months ago
JohnnyD 12 months ago

The only way to have a chance to avoid bias is to take all the stream part of the time. Take part of the stream generates bias in any case. It can be used for process control just to observe variations assuming the bias is always the same (which is rarely the case).
Use a cutter crossing the stream at the downward vertical discharge of the pipe. If the flow is high use linear cutter, else Vezin sampler.

Alan Carter
12 months ago
Alan Carter 12 months ago

Also important to remember, that all the particles should have same chance to get into the sample stream from the sampler's cutter. Usually this means that the cutter width / aperture used would have to be at least three times bigger than the nominal maximum particle size. So you can quickly calculate from there how much sample you're getting with one cut, and whether you need secondary samplers sampling the sample stream itself or not.

John Koenig
12 months ago
John Koenig 12 months ago

Thank you all.

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