Defender 500 offers high efficiency cleaning of ventilated crankcase gases in diesel and gas engines. The unit reduces engine emissions and ensures maximum protection for the turbocharger and intercooler for closed crankcase systems.

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A complete crankcase ventilation system

The Alfa Laval Defender 500 oil mist separator minimizes crankcase gas emissions. It serves as a complete engine crankcase ventilation system, including cleaning of gases and built in crankcase pressure control. By protecting the turbocharger and intercooler, the Defender 500 helps maintain high engine performance and prolong engine life for closed ventilation systems (CCV). The unit is designed for built-on installation on off-road, marine, rail, military and stationary engines covering a wide range of industries. Among others, it can be installed on construction vehicles, workboats, ferries and genset power stations.
Defender 500 fulfills emission legislation, ensures environmental and health safety as well turbo protection for CCV applications and it is maintenance free.

Efficiency of more than 98%

The Defender 500 uses centrifugal separation technology to clean the ventilated crankcase gases. Oil droplets and soot are removed from the blow-by and returned to the oil sump. Only clean blow-by gases are then returned to the engine turbo or to the ventilation outlet. Cleaning efficiency is more than 98% which is superior compared to most oil removal technologies.

Standing tough environments

Special features make the Defender 500 highly resistant to higher operating temperatures and allow operation at various angles, conditions often encountered in marine, offroad or rail applications. The Defender 500 will provide high cleaning performance and maintenance-free operation for the toughest engine duties.

Complying with emission regulations

The Defender 500’s capability to minimize oil aerosols and soot particles in crankcase gas will help builders of industrial diesel and gas engines for a broad range of applications to comply with the more stringent global emission regulations (Tier 4, for example) coming into force from 2015 onwards.


The Defender 500 has a capacity of up to 500 litres of blow-by gas per minute and is recommended for diesel and gas engines with displacements higher than 16 litres. For more information about available capacities, please check the table shown below and go to the Defender 500 documentation section to download the product data leaflet.



Engine displacement (liters)

Engine capacity (kW)

Engine blow-by (l/min)

Defender 500 (single unit)

16 - 50

500 - 1000

100 - 500

Defender 500 (double units)

  50 - 80

1000 - 2000

500 - 1000

Defender 500 (triple or more units)




Features and benefits

  • All-metal housing/casing, high temperature FKM (Viton) seals, off-road turbine: Optimized for the toughest off-road and high temperature duties
  • High performance disc stack technology: Cleaning efficiency higher than 98%
  • Integral pressure control valve: Maintains stable crankcase pressure
  • Hydraulic drive and compact, robust design: No external drive needed, suitable for a variety of conditions and duties
  • Oil return and re-use of drive oil: Minimum engine oil consumption
  • Minimizes coke deposits with clean inlet air (for CCV installations)
  • Maximized turbocharger efficiency
  • Oil-free inlet air: Maximizes intercooler performance
  • Protects turbocharger and intercooler: Maintains high engine performance and prolongs engine life for closed ventilation systems (CCV)
  • 90° “soft flow” connections: Improved flow characteristics
  • “Fit-and-Forget”, Defender 500 is sealed for life: No cleaning, no service, no replacement parts needed
  • Long working lifetime: Estimated 20,000 hours
  • Actively extracts gases from the crankcase: No pressure drop
  • Wide capacity range: Can be fitted to any gas or diesel engine, for larger capacities more than one unit can be installed
  • Manufactured and tested in Sweden: High quality manufacturing


How it works

Centrifugal separation

The engine crankcase gas must be continuously ventilated from the crankcase in order to prevent over-pressure. The Defender 500 oil mist separator removes oil droplets from the ventilated gas using Alfa Laval’s patented disc stack centrifugal separation technology. Installing the Defender 500 directly to the crankcase breathing channel allows oil droplets to be removed quickly and returned to the oil sump.

Hydraulically driven

Using a small, efficient turbine powered by minimal oil pressure from the engine enables the centrifugal rotor, fitted with conical discs, to spin. The rotation creates a centrifugal force that separates the heavier oil droplets and soot particles from the ventilated gas. The oil and soot are forced off the discs on to the separator housing wall where they drain to the bottom chamber of the housing, mixing with the returning drive oil, and drain back to the sump.

The cleaned gas is vented to the surroundings for an open system (OCV), or returned to the air intake of the engine for a closed crankcase ventilation system (CCV).

Integrated Pressure control

In addition to being a separator unit, the rotating disc stack works as a fan that extracts gas from the crankcase. Therefore, there is no pressure drop across the unit. An internal pressure control valve ensures the crankcase pressure is within a suitable working range, despite potential pressure variations. The built-in membrane and spring act as a closure valve when low pressure builds up downstream of the separator, providing pressure control and, thus, protection against too low pressure in the crankcase.