Oil processing in a vacuum


Sans-titre-3The standard treatment makes it possible to purify the oil by eliminating solid particles by fine filtration using an interchangeable filter cartridge, and eliminating the water and dissolved gasses by evaporation in a vacuum after heating the fluid to about 70 to 90°C (temperature adjusted depending on the properties of the fluid to be treated).

ARRAS MAXEI treatment equipment is globally recognised to be remarkably reliable thanks to an ingenious design process which has been widely tested and improved over time, making it possible to combine the simplicity of the process and its low operating costs with an excellent level of performance.

For example, on the basis of standard quality mineral oil (with a distillation curve of 0.01 mb at 80°C) containing 50 ppm of water and 10% of dissolved gasses for an input temperature of 70°C minimum, the oil will be returned following a single passage with a concentration that is 10 times lower (<5ppm) and a dissolved gas content divided by almost 100, thereby raising its breakdown voltage above 75 kV.

When starting at 20 ppm of water, its content passes to 3 ppm after treatment (these performances may vary depending on the oil specifications and composition, its temperature and its level of « pollution »).

Furthermore, we offer our customers many catalogue or specific options to meet all their needs and make it possible for each machine to be perfectly adapted to all possible usage modes and to the strictest requirements.

ARRAS MAXEI offers you a line of treatment machines from a standard production of 300 to 12,000 litres/hour and significantly beyond these values if necessary (there is a 30,000 litre/hour machine in service in Eastern Europe).

This line is available with three levels of equipment depending on their use:

The XeLean (ex-THV) series includes a heating unit using immersed heating elements, the degassing tank with its vacuum unit, the cartridge filter the introduction pump & the extraction pump in order to make the circulation of the fluid. This basic treatment machine – at the atmosphere – suits to workshop or construction work. It allows to treat from tank to tank or to treat new and old transformers. This range of product can treat up to 20 meters ditance.

The MAS series is recommended for on-site treatments or for direct connection to the tank of the transformer to be treated (continuous multi-pass treatment). This range of product allows to treat transformer under vacuum and to realize treatment up to 50 meters disctance. Numerous options and personalization can be realized on this range of product ( heat power supply increase, roller-unwinder, double degassing tank, etc…)

The TEC series has an additional specific connection system to a degasser and a high safety automated control system to allow the transformer to be treated while running. The transformer can therefore remain fully operational throughout the treatment phase. The only constraint is to make sure that the connection system on the tank is at a sufficient safety distance from the terminals and other live parts when connecting and disconnecting the machine to and from the transformer (otherwise a 2 to 4 hour power supply shut down will be needed).

On our machines these critical phases are highly secured (the slightest intake of air or gas into the oil circuit can lead to an instant and destructive voltage breakdown of the running transformer), driven and controlled step by step by a PLC in order to prevent any operator errors and the human and material consequences they could have.

All our machines are equipped with standard instrumentation required to monitor the process (fluid pressure and temperature with high threshold safety, filter load loss, vacuum level in the degasser, etc.) which can be enriched according to customer requirements.

The catalogue of options makes it possible to customise your machine, some of the equipment being available on the standard models depending on the series or machine versions. This is a non-exhaustive list (contact us for further information): :


  • Flexible tank on a tubular frame
  • Rigid casing
  • Rigid casing with a load bearing fame (allowing it to be lifted using a crane or a gantry crane)
  • Installation in a container, …

Chassis / Mobility

  • Assembly on a skid (workshop platform with handling wheels)
  • Site trailer (platform with rubber wheels, max. speed 10Km/h)
  • Road trailer (platform with inflatable wheels, max. speed 90Km/h)
  • Assembly on a truck, …

Sans titre


  • Heat recovery device between the outgoing and ingoing fluid to make energy savings (especially recommended for static installations)
  • Gradual electronic heating unit drive
  • 400V Three phase, 220V three phase, 400V/220V dual voltage three phased power supplies
  • Control and automatic reverse of the phase direction, …


  • Manual or electric cable and/or connection piping winders
  • Power generator for stand-alone operation, …

Strengthened function

  • Reinforced heating: 30kW to 200kW (for special weather conditions, reduced cycle times, etc.)
  • Stronger vacuum with a Roots type vacuum pump for big installations, distillations using a higher vacuum, additional inlets and outlets to create the vacuum in the transformer tank when filling with oil, …
  • Condenser and cooling unit with a two-staged unit to monitor the quantity of evaporated water and the best protection for the vane pump
  • Specially shaped evaporators for special applications
  • Additional connections (vacuum to fill tanks in a vacuum, heating circuit for prior tank heating, oil for multiple connections, etc.) with the possibility of having manual or automated valves, …

Installation control, on line measurement and treatment

  • Monitoring making it possible to monitor all treatment parameters and drive the installation remotely from a PC interface with an internet or GSM connection.
  • Remote monitoring making it possible to run without staff present at the machine, the operator is notified of all deviations, alarms and anomalies on the installation by SMS
  • Vacuum pump condensate safety by an alarm on the damper high position or automatic purge
  • Installation isolation safety valve that automatically isolates the machine from the transformer in the event of an anomaly
  • Additional instrumentation: oil flow meter, volume meter to measure treated quantities, energy monitoring, TFT screen control command, data recorder
  • Treatment monitoring: on line water content measurement, accurate on line vacuum measurement using a Pirani gauge
  • Oil regeneration using a special treatment cycle using « Fuller’s earth » (Acidity treatment, delta tangent, colour, etc.)
  • Corrosive atmosphere: corrosion treatment and specific paint, reinforced cable protection, etc.

Furthermore, ARRAS MAXEI can satisfy many other oil treatment or other special fluid requirements (Jarilec, Midel, FC72, etc.).