P Separators 626/636

P-separators are designed for automatic operation in periodically unmanned engine rooms at sea and in automated power stations ashore.

Application P-separators

P-separators are based on purifier technology, which means that the oil/water interphase is manually adjusted by means of a gravity disc. Because the separators do not automatically adjust to varying oil density, they are most suitable for economical cleaning of the following:

  • Lubricating oils
  • Distillates
  • Lighter diesel oils

If the oil is well defined and does not vary in density, P-separators can also be manually adjusted to clean heavy fuel oils with densities up to 991 kg/m3 and viscosities up to 600 cSt/50°C.

P-separators are designed for automatic operation in periodically unmanned engine rooms at sea and in automated power stations ashore.

Scope of supply

The S and P Flex separation concept provides a wide range of alternatives for P-separators. Depending on the need, a P-separator can be supplied as a separator and ancillaries, as a customer-specified module, or as part of a comprehensive package including services and order-specific documentation.

Flex system

A P-separator with ancillaries in the form of optimized block components provides full say over the use of space. This allows for local modularization or do-it-yourself assembly.

Flex modules

A compact P-separator module can be built to a customer-specified configuration from a wide range of modular skids and machine blocks. Multi-modules are possible, as well as mixed modules including one or more S-separators and/or P-separators for the simultaneous treatment of different types of mineral oils. All Flex modules are factory tested to ensure faster start-up and commissioning.

Single flex module with separatorSingle flex module with separator, heater and pumpQuadruple flex module

Single flex module with separator (excluding heater and pump)

Single flex module with separator, heater and pump

Quadruple flex module with separators, heaters and pumps

Features and benefits

Small footprint, high flexibility
The small separator and the modular nature of the surrounding components allow easy installation and flexible positioning in the engine room.
No water tank
No tank is needed to supply operating water, which further simplifies installation.
High separation efficiency
An optimized design ensures the best possible separation efficiency from the bowl and disc stack.
The CentriShoot discharge system greatly reduces sludge volumes. Its fixed discharge slide flexes gently to expose the discharge ports, thereby eliminating metalto- metal wear.
The CentriLock bowl-locking system uses a lightweight, non-threaded snap ring. This prevents wear by allowing easy removal without a sledgehammer.
Long service intervals
Wear-preventing features like CentriShoot and CentriLock reduce the consumption of spare parts and allow planned maintenance to be performed less often. This reduces operating costs.
Easy operation and service
The new PLC based EPC 60 controller is designed for "one-button" starts and stops, as well as intuitive menu navigation. Information about parameters and alarms can be easily accessed, which simplifies both operation and troubleshooting. The EPC 60 also has a modular construction that enables faster troubleshooting and I/O board replacement.
Remote control and monitoring
Using Ethernet or Bus communication, Flex systems and modules based on P-separators 626/636 can be operated and supervised remotely from the control room. A variety of alarm functions are available as standard, and extra I/O boards can be added to the EPC 60 controller in order to enhance its operating and monitoring capabilities.

Optional equipment

Flex separation systems based on P-separators 626/636 can be complemented with the following equipment:

  • Starter (included in module versions)
  • Heater
  • Space heating
  • Additional thermometers
  • Vibration sensor kit
  • Feed pump
    • Supplied loose
    • Mounted on a separate skid
    • Incorporated into a module
    • As a pump module (multiple pump skids mounted together)
  • Flow regulating system
  • Sludge removal kit
  • Sludge outlet butterfly valve kit
  • Steam shut-off valve kit
  • Air pressure reducer valve
  • Pipe arrangement for multiple modules, including heater cross-connection
  • Emergency safety shutdown
  • Remote monitoring and control
  • Separator lifting tool

Feed pump options


Schematic diagram

  1. Feed pump
  2. Heater
  3. Temperature transmitter
  4. Safety valve
  5. Change-over valve
  6. Process controller
  7. Pressure transmitter - oil
  8. Complete regulating valve
  9. Regulating valve - oil
  10. Pneumatic shut-off valve
  11. Valve block water
  12. Separator
  13. Pressure transmitter - water
  14. Drain valve
  15. Sludge removal kit
  16. Regulating valve

Operating principle


A Flex separation system based on a P-separator 626/636 is operated automatically by the EPC 60 controller. Untreated oil, heated to the correct temperature, is fed continuously to the separator, which is driven by an electric motor via a friction clutch and belt.

The separator bowl is fixed at the top of a spindle, which is supported by bearings and special composite springs. This bowl can be arranged as a purifier or as a clarifier. Both configurations remove sludge, which accumulates at the bowl periphery and is intermittently discharged by the high-precision CentriShoot discharge system.

In a purifier configuration, both sludge and water are separated from the oil, which means that water is continuously discharged from the bowl. The EPC 60 controller automatically controls the admission of water for the water seal and the displacement of oil prior to sludge discharge, but a gravity disc is needed to establish the correct interphase position in the separator bowl, i.e. the boundary between the oil and the water seal. The size of the gravity disc must be matched to the oil's density, viscosity/temperature and feed rate to the separator.

System Layout

In a clarifier configuration, a clarifier disc is fitted instead of a gravity disc. The water outlet is blocked, which means that the separator's water-handling capacity is limited and that water accumulates like sludge.

During normal operation, vital process parameters are monitored. These parameters, as well as alarms, are indicated by easy-to-understand text messages on the LCD display of the EPC 60 controller.

The EPC 60 controller provides many alarm functions, including alarms for low oil pressure, high sludge tank level (if the optional sludge removal kit is included) and power failure. Additional functions are available for a vibration alarm when the optional vibration sensor is fitted.


Instead of a sliding bowl bottom, the CentriShoot discharge system features a fixed discharge slide that flexes at its edge. This increases discharge accuracy and does away with metal-to-metal wear.

Conventional lock rings are threaded and must be removed with a sledgehammer. Over time, the metal-to-metal wear between bowl and lock ring can lead to expensive bowl repair or replacement.

Step One:
CentriShoot Step OneCentriLock Step One

The CentriShoot discharge slide is fixed at the centre. During separation, the slide covers the discharge ports.

An Allen key is the only tool needed to work with CentriLock. No sledgehammer is necessary.

Step Two:
CentriShoot Step TwoCentriLock Step Two

During sludge discharge, the edge of the slide flexes downward, exposing the discharge ports.

The CentriLock snap ring lifts out and snaps in easily - without any threads to wear.

Step Three:
CentriShoot Step Three

Instead of a conventional lock ring, the CentriLock bowllocking system features a non-threaded snap ring. This lightweight ring snaps quickly into place and is easily removed with only an Allen key.


Preventive maintenance procedures are handled quickly and simply with the help of a compression tool. The snap ring of the patented CentriLock bowl-locking system is non-threaded and requires only an Allen key to remove.

Maintenance intervals:
Inspection Service every 4 000 h or 6 months
Overhaul Service every 12 000 h or 18 months
Service spares kits contain all necessary spare parts for each service and tips for maintenance in checkpoints:
Inspection Kit with O-rings and seals for separator bowl
Overhaul Kit with parts for drive system, belt, bearings and pads, also containing an Inspection Kit
Support Kit with strategic spares for operation and maintenance backup
The System Manual includes detailed information in electronic or printed form:
Installation instructions
Operating instructions
Alarms and troubleshooting
Service and spare parts
Commissioning and technical services are available from all Alfa Laval offices, including startup assistance and advice on operation and maintenance
Training in all aspects of oil treatment, freshwater generation and heat transfer is available
All services can be incorporated into specially tailored Nonstop Performance packages. Details are available from local Alfa Laval offices

Max. Recommended Capacity, l/h on lubricating oils for trunk piston engines

max capacity

Technical Data

Main supply voltage3-phase, 220 V up to 690 V
Control voltage1-phase, 100/110/115/230 V
Frequency50 or 60 Hz
Control airMin 5 bar, max 8 bar
Operating water pressureMin 2 bar, max 8 bar
Flex SystemSize (height x width x length)*Net Weight*
P 626895 x 750 x 1075389 kg
P 636975 x 750 x 1195443 kg

* Dimensions and weights for Flex systems do not include control cabinet.

Flex ModuleSize (height x width x length)**Net Weight**
P 6261750 x 750 x 1075505 kg
P 6361750 x 850 x 1195585 kg

** Dimensions and weights for Flex modules do not include pump and heater.

More Information
Flow (L/H)4600