Hydrocyclone vs hydrocyclone separator
The same piece of equipment in two distinct operating modes

Our clients often ask where the line lies between a hydrocyclone and a hydrocyclone separator. Strictly speaking there is no new piece of equipment involved. Both units share the same body, tangential inlet, vortex finder and apex. What changes is the way the underflow and overflow are managed. That configuration shift turns a single piece of equipment into either a precision classifier (hydrocyclone) or a dedicated dewatering unit (hydrocyclone separator). 


Every application starts with this same hydrocyclone body; performance shifts only when we add or remove the discharge regulator and siphon attachments.


One design, two flow control elements 

A standard hydrocyclone relies on an open apex to discharge coarse particles and a short overflow pipe to evacuate fines. Install two additional items, and the same vessel switches to hydrocyclone separator duty: 

  • Discharge regulator (fishtail) mounted below the apex keeps the spigot partially closed until the weight of settled solids forces it open. 
  • Extended overflow pipe with a siphon control valve creates a partial vacuum that holds the fishtail shut whenever little or no solids are present, preventing unwanted water carry-over. 

These simple attachments let the hydrocyclone separator maintain a steady, high-density underflow even as feed tonnage or solids concentration fluctuates. 



This image shows the extended overflow pipe (1) with siphon control pipe (2), and the discharge regulator (fishtail) (3).


The vacuum in the overflow pipe (1) can easily be regulated with a valve at the bottom of the siphon control pipe (2).


Hydrocyclone mode: cut size control 

When the fishtail and siphon are absent, the unit operates as a conventional hydrocyclone. With feed pressures typically above 1 bar and a stable slurry composition, the internal vortex remains symmetrical, delivering a predictable d₅₀ and a sharp partition curve. This makes the setup ideal for grinding-circuit classification and fines recovery where underflow moisture is not critical. 


Hydrocyclone separator mode: high-density dewatering 

Fitting the discharge regulator (fishtail) and siphon transforms the same cyclone body into a dewatering workhorse. A Kinarox Sepa Separator, for example, reaches 72 – 75 wt % solids in the underflow while sending nearly all process water to the overflow. The siphon effect closes the fishtail whenever the solids content in the feed falls, so the stockpile is not washed away during low-load periods.


Three Kinarox Sepa hydrocyclones working in a separator setup.


Configuration checklist

Operating Objective Required Attachments Typical Pressure Window Expected Underflow Solids
Size Classification None (open apex, standard overflow) ≥ 1 bar 45 – 60 wt %
Dewatering / constant density Discharge regulator + extended overflow with siphon valve 0.5 – 1 bar 70 – 75 wt %


Material options for long service life

Hydraulic performance is only one side of the equation; wear life is equally decisive for total cost of ownership. We supply replaceable liners in natural rubber, oil-resistant synthetic rubbers, and specialty elastomers that withstand chemical attack in aggressive feed streams. Selecting the correct liner compound protects the vortex finder, cone and apex from abrasion, swelling or chemical softening, keeping separation efficiency stable between maintenance intervals. 


We stock hydrocyclone wear parts in various materials such as natural rubber, oil-resistant synthetic rubber, and other specialty elastomers for specific applications.


How we can he​lp 

Do you need help selecting the right configuration and liner material for your specific application? Our process engineers are available to size the equipment, choose the correct attachments and specify the most suitable liner compound for your slurry chemistry.

Or are you just looking for hydrocyclone spare parts in Europe?

Contact us and we will provide a tailored recommendation!