A high speed disperser (also called a dissolver or high-speed mixer) is the standard pre-dispersion and mixing machine in coatings, inks, adhesives and chemical manufacturing. It uses a high-speed rotating disc (toothed or sawtooth) to create shear and turbulence, wetting pigment agglomerates and reducing them to a size that downstream bead mills can finish efficiently. This guide covers disperser specifications, selection criteria, configuration options and total cost of ownership.
How a high speed disperser works
The disperser shaft rotates at 500-1,500 rpm, driving a toothed disc through the product. The disc creates a strong vortex that draws pigment from the surface down into the liquid. At the disc edge, tip speeds of 15-25 m/s create high shear that breaks pigment agglomerates and wets individual particles. The result is a uniform premix with fineness typically 20-50 microns, ready for fine grinding in a bead mill or basket mill.
High speed disperser specifications: what the numbers mean
| Specification | POLYC range | What it determines |
|---|---|---|
| Vessel capacity | 50 L - 5,000 L | Maximum batch size |
| Motor power | 4 kW - 132 kW | Shear energy and maximum viscosity |
| Shaft speed | 0 - 1,500 rpm (variable) | Tip speed and shear intensity |
| Disc diameter | 150 mm - 800 mm | Vortex formation and shear zone |
| Tip speed | 10 - 25 m/s | Wetting efficiency and pigment dispersion |
| Maximum viscosity | Up to 100,000 cP | Product range (higher = more power needed) |
| Lifting stroke | Hydraulic, 600 - 2,000 mm | Vessel changeover and cleaning |
| Vacuum capability | Optional, -0.09 MPa | Degassing for high-gloss products |
Disperser configurations compared
1. Single shaft high speed disperser
The most common and economical configuration. One high-speed shaft with a toothed disc, suitable for low-to-medium viscosity products (below 50,000 cP) that do not require wall scraping. POLYC single shaft dispersers range from 50 L to 2,000 L with 4 kW to 75 kW motors, suitable for standard paints, inks and adhesives.
2. Vacuum dispersing machine
A single shaft disperser mounted on a vacuum lid, allowing operation under reduced pressure. This removes air trapped during high-shear mixing, producing bubble-free products with better gloss and clarity. POLYC vacuum dispersers achieve -0.09 MPa and are the standard choice for automotive clears, high-gloss coatings and optical adhesives.
3. Double shaft high speed disperser
Two high-speed shafts operating in the same vessel, either concentric or offset. The second shaft increases shear and improves circulation in large vessels or high-viscosity products. POLYC double shaft dispersers range from 500 L to 5,000 L with 22 kW to 132 kW total power, suitable for high-solids coatings and pigment concentrates.
4. Mezzanine (platform) disperser
A disperser mounted on a platform above the vessel, with the shaft passing through a hole in the platform. This allows the vessel to be moved underneath on a trolley, simplifying vessel changeover in multi-product facilities. POLYC PSD mezzanine dispersers are commonly used in colourant and ink production where multiple vessels are rotated through one disperser.
How to select the right disperser
Step 1: Size motor power by vessel and viscosity
The most common sizing error is underpowering. As a rule of thumb: low-viscosity products (below 10,000 cP) need 0.03-0.05 kW per litre; medium viscosity (10,000-50,000 cP) need 0.05-0.08 kW per litre; high viscosity (50,000-100,000 cP) need 0.08-0.12 kW per litre. A 1,000 L vessel processing pigment paste at 50,000 cP needs at least 55 kW. Underpowered dispersers cannot form a proper vortex, take longer to wet pigment, and run hot.
Step 2: Match disc diameter to vessel
Disc diameter should be 25-35% of vessel inner diameter. Too small and the vortex does not reach the vessel walls, causing dead zones. Too large and the disc draws air into the product, causing foaming. For a 1,000 mm diameter vessel, use a 300-350 mm disc. Discs are interchangeable, so it is common to have one larger disc for low viscosity and one smaller for high viscosity.
Step 3: Decide on vacuum and wall scraping
Vacuum is essential for high-gloss clears, automotive coatings and any product where bubbles affect appearance or performance. If your product is a standard matte paint or primer, vacuum may not be necessary. Wall scraping (anchor or gate scraper) is needed for products above 50,000 cP or products that tend to cake on vessel walls. For products below 50,000 cP, the vortex alone provides sufficient wall turnover.
Step 4: Evaluate material handling and automation
Consider how vessels are moved and how powder is added. Manual powder addition through a hopper is standard; automated powder feeding systems reduce dust and improve consistency. For facilities running more than 5 batches per day, hydraulic lifting with quick-release vessel clamps reduces changeover time. PLC control with recipe management stores speed, time and vacuum settings for each product, improving batch-to-batch consistency.
What affects disperser price
- Size and power: a 2,000 L, 75 kW disperser costs 3-4 times a 200 L, 11 kW unit
- Vacuum system: vacuum lid, seal and vacuum pump add 20-30% to base price
- Double shaft: second shaft and motor adds 40-60% over single shaft
- Wall scraping: anchor scraper with separate drive adds 25-35%
- Lifting system: hydraulic lifting is standard; mechanical lifting reduces cost for small machines
- Automation: PLC with recipe management, variable frequency drive and temperature monitoring adds 15-25%
- Material of construction: standard carbon steel vessel with stainless steel contact parts; full stainless steel 316L for pharmaceutical or food adds 30-50%
- Certification: CE marking, ATEX explosion-proof and FDA-compliant materials add engineering and documentation costs
Key Takeaways
- High speed dispersers are pre-dispersion machines, not fine grinding machines - they achieve 20-50 micron fineness, suitable for feeding bead mills
- Size by motor power: allow 0.03-0.12 kW per litre depending on product viscosity
- Disc diameter should be 25-35% of vessel diameter for proper vortex formation
- Vacuum is essential for high-gloss and bubble-sensitive products; wall scraping for viscosity above 50,000 cP
- Single shaft is most economical; double shaft for large vessels or high-solids products; mezzanine for multi-vessel facilities
Frequently Asked Questions
Can a disperser replace a bead mill?
No. A disperser achieves 20-50 micron fineness through high-shear wetting. A bead mill achieves 50 nm to 10 micron fineness through media grinding. For products requiring fineness below 20 microns, a disperser is used for pre-dispersion followed by a bead mill or basket mill for fine grinding.
What is the maximum viscosity a disperser can handle?
Standard single shaft dispersers handle products up to approximately 50,000 cP. With wall scraping and higher power, they can handle up to 100,000 cP. Above 100,000 cP, a planetary mixer or double/triple shaft mixer is more suitable because the product does not flow properly around a single high-speed shaft.
How long does dispersion take?
Typical dispersion time is 20-60 minutes per batch, depending on pigment loading, viscosity and target fineness. High-pigment-load concentrates (70-80% solids) may take 60-90 minutes. The process is complete when the Hegman gauge reads the target fineness (typically 5-7 Hegman for pre-dispersion).
What is the difference between a disperser and a dissolver?
There is no functional difference. "Dissolver" is the common term in Europe and Asia, while "disperser" is more common in North America. Both refer to the same high-speed, toothed-disc mixing machine. Some manufacturers use "high speed disperser" for the standard machine and "dissolver" for vacuum versions, but this is not universal.
Related POLYC MACHINE equipment
- Vacuum Dispersing Machine - 100 L to 2,000 L, vacuum degassing for high-gloss products
- Double Shafts High Speed Disperser - 500 L to 5,000 L, dual high-speed shafts
- PSD Mezzanine Disperser - platform-mounted for multi-vessel facilities
- IDS Inline Dispersion Machine - continuous inline dispersion for high-volume production
Need help selecting the right disperser for your product? Request a free process consultation with our engineering team. We can recommend the optimal configuration, motor power and disc size for your formulation and production volume.