High-shear emulsification head

01

Set the tip speed for the droplet size

Charles Ross & Son describes conventional high-shear mixers as a four-blade rotor running at tip speeds of 3,000–4,000 ft/min within a close-tolerance fixed stator, creating mechanical and hydraulic shear by drawing product into the rotor and expelling it radially through the stator openings. Running at a particular tip speed yields a corresponding equilibrium size distribution; once reached, further passes at the same speed give diminishing returns, so Ross recommends the maximum speed setting for size reduction, except for shear-sensitive applications. [1]

Where the maximum speed of a conventional rotor–stator still falls short, Ross points to ultra-high-shear mixers operating around 11,000–18,000 fpm, which can produce smaller particles; Ross writes: "In many applications, ultra-high shear mixers effectively replace colloid mills and even deliver higher throughput." In its emulsion report Ross writes: "Generally, the higher the shear put into creating the emulsion, the finer the droplets produced, and the more stable the emulsion." It adds that but some emulsions coalesce beyond a certain shear level, and droplet size falls sharply in the first few passes before levelling at an equilibrium. [1] [2]

Editorial calculation: 3,000–4,000 ft/min ≈ 15.2–20.3 m/s and 11,000–18,000 ft/min ≈ 55.9–91.4 m/s (1 ft/min = 0.00508 m/s). [1]

Give the supplier the formulation, viscosity range, target droplet or particle size, batch volume and vessel geometry, temperature, required tip speed or rpm, stator screen options, sanitary or explosion-proof requirements, materials of construction and motor supply.

02

Understand how the workhead mixes and circulates

Silverson explains that the high-speed rotor exerts suction drawing liquids and solids up from the bottom of the vessel into the workhead centre; centrifugal force drives them to the periphery where they are milled in the precision-machined clearance between rotor blade tips and stator wall, followed by intense hydraulic shear as they are forced out through the stator perforations; the radial expulsion and suction set up a circulation pattern that minimises aeration from surface disturbance. [3]

Silverson lists its AX series pilot-scale batch mixers for capacities up to 50 litres, with the AX5 variable-speed to a nominal 6,000 rpm for mixing, emulsifying, homogenising, disintegrating and dissolving. [3]

Editorial calculation: tip speed = π × rotor diameter × rpm, so at 6,000 rpm a 3,000 ft/min (15.2 m/s) tip speed corresponds to a rotor of about 48 mm diameter. [3] [1]

03

Check the viscosity range and hygiene standard for the head type

Admix's page for its Rotosolver sanitary in-tank high-shear mixer compares mixer types by viscosity range: its own open rotor/stator head at 1–50,000 cP, low-speed agitators and high-speed saw-tooth disc dissolvers at 1–100,000 cP, and fixed-stator close-clearance high-shear mixers at 1–25,000 cP, with shear rated high to very high for the close-clearance type and moderate to high for its own. It states the Rotosolver meets 3-A sanitary standard 73-01 and USDA-AMS standards, can have an all-stainless head, shaft, drive and motor, has a one-piece clean-in-place mix head with no wearing parts in the product zone, and scales from lab models to production sizes of up to 100 hp. Admix also claims, against competing designs, 30–50% less energy, 10–20% higher tip speeds, 200–600% higher flow and batches up to six times faster; these are the maker's own comparisons. [4]

Editorial calculation: 100 hp is about 75 kW. A product near 25,000 cP sits at the top of the range Admix gives for close-clearance stators, so for thicker products ask for a trial at your viscosity or a head with more flow; for food, dairy or cosmetics, ask which 3-A or other hygienic standard the head is certified to and how it is cleaned in place. Treat the maker's energy and speed comparisons as claims to test on your batch. [4] [3]

04

Compare what suppliers offer

The supplier linked to this page lists emulsifying and high-shear homogenizing equipment; its card links to the page reviewed.

Ask any supplier for rotor diameter and maximum rpm (tip speed), rotor–stator gap and stator screen options, motor power, batch capacity range, wetted materials and surface finish, seal type, sanitary or ATEX ratings, and trial data on your formulation.

05

Trace what each part does

This is a functional reference built from the sources cited; it is not one maker's specification.

06

Fill the specification fields with values for your order

A high-shear head quotation needs values for your product. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

07

Send the formulation, target size and batch data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Product: [phases; viscosity; temperature]
Target: [droplet or particle size]
Batch: [litres; vessel shape]
Head: [tip speed; rpm; stator screens]
Construction: [wetted material; finish; seal]
Compliance: [sanitary; ATEX]
Trial: [lab test on your formulation]

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