The Alfa Laval CHNX 418 B31-G is a nitrogen-purged horizontal decanter centrifuge for flammable and hazardous sludges. ATEX certified, 418 mm bowl at 4,000 RPM, 100 GPM rated capacity, 20 HP drive. Dolphin Centrifuge supplies and services the CHNX 418 from Warren, Michigan.
Operation
The Alfa Laval CHNX 418 B31-G is a horizontal de-sludging centrifuge built for the two-phase separation of wastewater, crude oil tank bottoms, municipal sludge-thickening, industrial sludge dewatering, paint sludge handling, and similar applications. It is a specialized variant of the NX 418 decanter centrifuge, engineered for processing sludges containing flammable, explosive, or otherwise hazardous constituents.
The defining feature of the CHNX 418 is its inert gas purge system installed for nitrogen purging of the operating space, including the container vessel and inlet feed pipe housing. This maintains a non-ignitable atmosphere within the bowl cavity, mechanical seal areas, and casing throughout operation.
With a 20 HP motor, the CHNX 418 decanter has a bowl RPM of 4,000 and can process 100 GPM of water with light sludge. The unit generates 3,150 G-Force and is ATEX certified for use in classified hazardous locations.
CHNX 418 Specifications
| Model Type | Alfa Laval CHNX 418 B31-G Decanter Centrifuge |
| Rated Capacity | 100 GPM on Water Sludge Thickening |
| Bowl Diameter | 418 mm |
| Bowl Speed | 4,000 RPM |
| G-Force | 3,150 RCF |
| Drive Motor Power | 20 HP |
| Auger Differential Speed | 1 ~ 50 RPM |
| GearBox Ratio | 1 : 159 (2.5 kN-M) |
| AE (Area Equivalent) | 1,565 |
| Conveyor Protection | Carbide Tile or Tungsten Carbide Hard-Surfacing |
| Inert Gas Purging | Gas Nozzle Manifold for Inert Gas blanketing of Vessel and Glands |
| Safety Certification | ATEX Certified |
Applications
The Alfa Laval CHNX-418 Decanter is used for the following applications.
- Steel Mill Tar Recovery
- Ethanol Extraction Centrifuge
- Waste Oil De-sludging
- Crude Oil Tank Bottom Sludge
- Municipal Wastewater
- Pyrolysis Sludge Separation
- Liquid Humus Fertilizer
- Sludge Thickening & Dewatering
Why Nitrogen Purging?
When a centrifuge processes sludge containing flammable solvents, the high-speed rotating bowl creates centrifugal aerosolization and off-gassing of volatile organic compounds. In standard centrifuges, these vapors can accumulate to ignitable concentrations inside the casing. The CHNX 418 addresses this risk by continuously flowing inert nitrogen gas through the bowl cavity and discharge areas, displacing any oxygen and preventing combustible mixtures from forming.
This approach is recognized by ATEX standards as an effective protective measure for centrifuge applications in Zone 1 and Zone 2 hazardous locations. Contact our engineering team to discuss whether the CHNX 418 or another explosion-proof centrifuge configuration is appropriate for your specific solvents and process conditions. See also our decanter centrifuge overview and decanter centrifuge applications for broader context.
Need the CHNX 418 for a Hazardous Application?
Dolphin Centrifuge supplies ATEX-certified CHNX 418 decanters for flammable sludge processing. Contact our engineers to review your application.
Frequently Asked Questions
What does the 'CH' designation mean in CHNX 418?
The 'CH' in CHNX 418 stands for 'Chemical Hazardous' — indicating this is a nitrogen-purged, ATEX-certified variant of the standard NX 418 decanter centrifuge designed for processing flammable, explosive, or otherwise hazardous sludges and slurries. The continuous inert gas purging system maintains a non-ignitable atmosphere throughout operation.
Why does the CHNX 418 use nitrogen purging instead of explosion-proof motors?
Explosion-proof motors alone do not protect the bowl interior from ignitable vapor concentrations. The CHNX 418 uses continuous nitrogen purging because the high-speed rotating bowl can aerosolize volatile organic compounds and create ignitable mixtures inside the casing. Nitrogen displacement eliminates oxygen from the bowl cavity and discharge areas, preventing combustible mixtures regardless of the electrical rating of the motor.
What industries use the Alfa Laval CHNX 418?
The CHNX 418 is used in solvent recovery and recycling, pharmaceutical manufacturing waste processing, chemical plant sludge with flammable content, petrochemical refinery slurries, paint and coatings waste, ink and resin waste dewatering, and adhesive and polymer slurry separation — any application where the feed contains flammable solvents or vapors requiring ATEX-classified equipment.
How does the CHNX 418 compare to the standard NX 418?
The CHNX 418 retains all the separation performance of the standard NX 418 — 418 mm bowl diameter, variable speed drive, 5–20 m³/hr throughput — while adding continuous nitrogen purging, ATEX certification, explosion-proof motors, and sealed casing with inert gas inlet and vent connections. The separation characteristics (G-force, scroll speed differential, pond depth) are unchanged from the base NX 418 decanter.
Does Dolphin Centrifuge supply and service the Alfa Laval CHNX 418?
Yes. Dolphin Centrifuge supplies reconditioned Alfa Laval CHNX 418 decanter centrifuges from our Warren, Michigan facility. Each unit is fully disassembled, inspected, rebuilt to OEM specifications, and tested with the nitrogen purge system verified operational before shipment. We also stock replacement parts and offer field service. Contact (248) 522-2573 for availability.
CHNX 418 Decanter — ATEX Certified, Nitrogen Purged
Dolphin Centrifuge stocks and services CHNX 418 decanters for hazardous sludge applications. Sample testing available.