From MAB to S-series
Alfa Laval has built high-speed centrifugal separators for the marine industry for over a century, and in that time the company has introduced a long line of separator generations, from simple manual-cleaning units to today’s fully automated ALCAP systems. Many of those generations are still hard at work in engine rooms around the world.
This guide explains every major Alfa Laval separator generation, how they relate to each other, and what each one means for spare parts, service and maintenance.
What are Alfa Laval separator generations?
An Alfa Laval separator generation is a product family that shares the same basic design, bowl construction, control philosophy and spare parts logic. Examples include the MAB, MOPX, FOPX and S-series. The generation is identified by the type designation on the separator’s nameplate, and it determines which service kits, bowl components and control units fit your machine.
Knowing your generation matters for one simple reason: parts are generation-specific. A service kit for an FOPX will not fit an MOPX, even though both machines do broadly the same job. Before ordering any spare part, the generation and the exact model within it, is the first thing to establish.
Alfa Laval separator generations at a glance
The table below summarises all ten generations covered in this guide, from oldest to newest. Each generation links to its dedicated page, where you’ll find the models we support and the parts we supply. Use the “Cleaning” column to see whether a generation requires manual bowl cleaning or discharges sludge automatically, and the “Interface control” column to see whether it relies on a manually selected gravity disc or adjusts itself using ALCAP technology.
| Generation | Era | Cleaning | Typical application | Interface control | Status |
|---|---|---|---|---|---|
| MAB | 1950s → today | Manual (solids-retaining) | Diesel & lube oil, smaller installations | Gravity disc | Still in production |
| MIB | Later compact manual series | Manual (solids-retaining) | Diesel & lube oil, small flows | Gravity disc | Current small-duty range |
| MAPX | First self-ejecting era | Automatic sludge discharge | Fuel & lube oil purification | Gravity disc | Legacy |
| MOPX | Self-ejecting workhorse era | Automatic sludge discharge | Mineral oils (fuel & lube) | Gravity disc | Legacy |
| FOPX | ALCAP introduction (1980s) | Automatic sludge discharge | Heavy fuel oil | ALCAP | Legacy |
| LOPX | ALCAP introduction (1980s) | Automatic sludge discharge | Lubricating oil | ALCAP | Legacy |
| MFPX | Compact ALCAP-era series | Automatic sludge discharge | Fuel oil, compact installations | ALCAP | Legacy |
| MMPX | Compact ALCAP-era series | Automatic sludge discharge | Lube & diesel oil, compact installations | ALCAP | Legacy |
| S-series | 2000s → today | Automatic sludge discharge (CentriShoot) | All fuel & lube oils, incl. HFO/VLSFO/biofuels | ALCAP | Current flagship |
| P-series | 2000s → today | Automatic sludge discharge | Well-defined oils (MDO, lube oil) | Mechanical platform | Current range |
The manual-cleaning era: MAB and MIB
The oldest generations still commonly found in service are the solids-retaining separators: machines with a bowl that collects sludge until an engineer opens it up and cleans it by hand. There is no automatic discharge. That makes these units mechanically simple, robust and inexpensive to run, but labour-intensive, which is why they are typically found on smaller vessels and installations with modest oil flows, or as dedicated diesel and lube oil units.
Their simplicity is also why they refuse to die. With a well-maintained bowl, fresh seals and the correct gravity disc, a solids-retaining separator from decades ago still does exactly what it was designed to do.
Generation MAB
The MAB is the archetypal solids-retaining Alfa Laval separator, configurable as either a purifier (removing water and solids) or a clarifier (removing solids only). Contaminated oil is fed through the centre of the bowl, centrifugal force pushes sludge outwards against the bowl wall, and a liquid seal prevents oil escaping through the water outlet.
The MAB is still in Alfa Laval’s current programme, which says everything about the soundness of the original design. Common models such as the MAB 103, 104, 204 and 206 remain widespread across the world fleet, and KET Marine keeps parts for all of them on the shelf.
Generation MIB
The MIB is the compact solids-retaining series for small oil flows, cleaning diesel oil and lubricating oil on smaller engines, generator sets and auxiliary installations. Like the MAB, it works as a purifier or clarifier with a manually cleaned bowl.
Its small footprint and minimal installation requirements have made it a fixture on fishing vessels, workboats and inland craft, where a full self-cleaning separator system would be oversized. Wear parts are few and affordable, which keeps the lifecycle cost of a well-serviced MIB exceptionally low.
The first self-ejecting separators: MAPX and MOPX
The step that changed shipboard oil treatment was the self-ejecting bowl. Instead of stopping the separator and dismantling the bowl to remove sludge, a self-ejecting separator opens its bowl ports for a fraction of a second at set intervals and shoots the accumulated sludge to the sludge tank. The machine can now run for thousands of hours between overhauls.
What didn’t change in this era was interface control. These generations still rely on a gravity disc: a precisely sized ring, selected to match the density of the oil being treated, that positions the oil/water interface inside the bowl. Selecting the correct disc is critical. The wrong disc breaks the water seal and causes oil loss or poor separation. That’s a routine job for an experienced engineer, but it’s also the single most common cause of trouble on these machines.
Generation MAPX
The MAPX series brought self-ejecting purification within reach of the general merchant fleet, and models such as the MAPX 204, 207 and 309 became fixtures in engine rooms worldwide. The design combines a proven high-speed disc-stack bowl with automatic sludge discharge, configurable for fuel or lube oil duty.
Production ended long ago, but MAPX units remain in daily service on older tonnage and because the design is well documented and parts remain available, keeping one running is a matter of routine maintenance rather than heroics.
Generation MOPX
The MOPX mineral oil purifiers with self-ejecting bowl is arguably the workhorse generation of the late twentieth-century merchant fleet. Designed for both fuel oil and lubricating oil treatment in marine installations and power stations, models like the MOPX 205, 207, 209 and 213 were built in enormous numbers. Many thousands are still in operation. For owners of older vessels, the MOPX question is rarely whether to keep it running but how: with regular intermediate and major service kits, correctly selected gravity discs, and reconditioned bowls when wear finally catches up.
Dedicated fuel and lube oil purification: FOPX, LOPX, MFPX and MMPX
In the 1980s Alfa Laval presented ALCAP, a separation technology it had been developing since the 1970s and it solved the gravity disc problem outright. An ALCAP separator has no gravity disc. Instead, a water transducer in the clean oil outlet continuously measures the water content of the treated oil. When water begins to break through, the control system automatically drains it or discharges it with the sludge. The separator adapts itself to the density of the oil, which means it handles low-quality and variable fuels with minimal oil losses.
ALCAP arrived together with a clearer split by application, spelled out in the type designations: F for fuel oil, L for lube oil, M for the compact marine series, with the X still marking the self-ejecting bowl.
Generation FOPX
The FOPX is the dedicated heavy fuel oil separator of the ALCAP introduction, built to clean high-density residual fuels that gravity-disc machines struggled with. Models such as the FOPX 605, 609 and 613 became the standard HFO purifier on a generation of newbuildings, paired with an EPC control unit that manages the ALCAP process. FOPX units are still abundant in the world fleet, and their electronics are one of the most common repair items KET Marine’s in-house electronics department handles.
Generation LOPX
The LOPX is the FOPX’s sister series for lubricating oil. Continuous lube oil cleaning removes the water and combustion residues that would otherwise accelerate engine wear, and the ALCAP principle is particularly valuable here because water contamination in lube oil can vary from trace amounts to sudden ingress. Exactly the variability ALCAP handles automatically. LOPX models such as the 705, 707 and 710 remain common companions to medium-speed and crosshead engines from their era.
Generation MFPX
The MFPX is the compact fuel oil series of the same technological family, designed for installations where space and throughput requirements are smaller. It offers the same self-ejecting operation in a smaller frame with a correspondingly compact parts inventory. Because the frames are small, complete reconditioned units and exchange bowls are a particularly practical option for this generation.
Generation MMPX
The MMPX rounds out the compact family on the lube and diesel oil side. These small self-ejecting separators are found on coastal vessels, superyachts, dredgers and gensets, anywhere continuous oil cleaning matters but engine room space is at a premium. Their compact bowls mean service kits are affordable and overhauls are quick, making a consistent maintenance rhythm easy to sustain.
The ALCAP era matured: S-series and P-series
Alfa Laval’s current marine separator programme is built around two ranges introduced in the 2000s, today marketed together as the S and P Flex concept.
The timing was no accident. Modern fuel realities demand a separator that adapts continuously rather than one set up once per bunker. That is precisely what the mature ALCAP platform delivers, and it is why so many operators of older generations eventually face the retrofit-or-maintain question covered later in this guide.
Generation S
The S generation is Alfa Laval’s flagship: an ALCAP machine with advanced software-based process control that can treat both heavy fuel oil and lubricating oil in a single module. It introduced two signature mechanical innovations: the CentriShoot discharge system, whose fixed flexing slide sharply reduces sludge volumes and eliminates metal-to-metal wear, and the CentriLock snap ring, which replaces the traditional threaded bowl lock (and the sledgehammer needed to open it) with a lightweight ring removed with an Allen key.
The result is longer service intervals, lower parts consumption and faster overhauls. S-separator systems are controlled by EPC-series controllers, and the range handles heavy fuel oils up to very high densities and viscosities.
Generation P
The P generation is the pragmatic counterpart within the Flex concept: a high-performance machine on a deliberately simple, low-wear mechanical platform, designed for well-defined oils of consistent, lower density — marine diesel oil and lubricating oils that don’t present the process challenges of residual fuels. Where the oil doesn’t vary, the P generation separators deliver the same outstanding separation with less complexity and lower lifecycle cost. S and P separators can be combined freely in mixed ship sets, which is exactly how most modern newbuildings specify them: S machines on the HFO/VLSFO lines, P machines on the diesel and lube duties.
Are spare parts still available for older Alfa Laval generations?
Yes, and this is where generation knowledge pays off. KET Marine has specialised in Alfa Laval separators since 1985, and we supply OEM-quality spare parts, service kits and reconditioned components for every generation in this guide. With over 30,000 items in stock, most orders ship the same or next day, worldwide, from our facilities in the Netherlands, Singapore and Greece.
Older generations bring one extra challenge: electronics. EPC control units for FOPX-, LOPX- and S-era machines fail long before the mechanical separator wears out, and replacements for discontinued controllers are scarce. Since 2018 KET Marine runs an in-house electronics department that repairs and tests separator control units at component level, often the difference between a straightforward repair and a forced system replacement.
Whether your separator left the factory last year or forty years ago, the maintenance logic is the same: correct parts, correct intervals, and a partner who knows the generation inside out.
If you have any questions, feel free to reach out!
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