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Hydroclone Trials

NOTE: This page may still have some revisions.

Hydroclone Trials

Hydroclone performance measurement

ChemIndustrial’s hydroclone product line is highly modular. Our modular components are quickly and easily assembled into a multitude of hydroclone configurations.

The resulting flexibility makes these hydroclones attractive to persons who need to evaluate hydroclone technology as a means for achieving some particular process separation.

To satisfy this need, ChemIndustrial offers customers the possibility of short-term use of a hydroclone system under the  HydrocycLOAN™ rental program.

 HydrocycLOAN™ program details are described elsewhere on this website. The purpose of this web page is to offer advice on to how to actually proceed with trials.

A typical hydroclone user needs to know the overall separation performance of his/her installation. The following paragraphs provide practical advice on how to measure and calculate this value.

Measuring hydroclone separation efficiency

The most common hydroclone application is to concentrate solids in a flowing liquid/solid mixture. In this application, the purpose of the hydroclone is to separate inlet flow into:

  • an overflow stream which contains less solids than the inlet flow and…

  • an underflow stream which contains more solids than the inlet flow.

Perfect information about hydroclone separation performance would require Mass balance trials. In layman’s terms hydroclone mass balance means this: The mass of everything that goes in to the hydroclone must come out of it.

Unfortunately, true mass balance trials are cumbersome. But, in most cases mass balance accuracy isn’t needed for practical evaluations of process separation.

The widely used quick and easy alternative to a mass balance trial is the Volumetric separation trial.

The main tool for manual volumetric separation trials is the Imhoff cone. This is a clear plastic 1000ml conical settling vessel with calibration markings and with a drain fitting at the apex of the cone. The drain fitting facilitates clean-out between trial runs.

To perform a volumetric separation trial, three Imhoff cones are required. Also, a support stand is needed to support the 3 cones in a vertical position while samples are settling.

Sample mixups must be avoided. We suggest the following standard arrangement for the support frame and the 3 positions for the samples in the frame.

  • With the 3-wide frame in front of you, label the FRONT LEFT.

  • Label the 3 sample positions from left to right as:

    • I (for the Inlet sample)

    • O (for the Overflow sample)

    • U (for the Underflow sample)

Imhoff-cones-3-with separation-sm

Actual trial run

We suggest using a standard form for gathering data during trial runs.  (Form will be ready soon.)

1.Decide on the hydroclone configuration to be tested during the run. Print the standard form and complete the required information.

2.Measure all 3 flow rates for the hydroclone.

  • Inlet flow rate

  • Overflow rate

  • Underflow rate

Record the 3 flow values:

  • Inlet flow rate = Overflow rate + Underflow rate

Flow measurements must be consistent with the above equation. For valid results, don’t go ahead without resolving any discrepancy.

3.Use the Imhoff cones to take one sample for each of the 3 flows.

Allow complete settling to occur. If the particles are small and/or light, settling may take some hours.

Record the 3 values on the form:

  • Inlet solids level (ml)

  • Overflow solids level (ml)

  • Underflow solids level (ml)

It is tempting to look at the 3 settled samples and draw an immediate conclusion about the hydroclone’s separation efficiency. But this measurement will not be accurate because inlet flow doesn’t usually split equally to overflow and underflow. Thus you must correct for the difference between the overflow rate and the underflow rate.

4. Complete the form by entering the results of the following three calculations:


And the separation performance is:




The Total separated solids value can be larger than the Inlet solids level value. One possible reason for this difference is the size of particles reporting to the hydroclone’s overflow (smaller particles) versus the particles reporting to the underflow (larger particles). Small particles can fit into the interstices among the larger particles in the undifferentiated inlet solids.