In industries where fuel and lubrication quality is critical—such as marine, power plants, and industrial operations—Alfa Laval’s centrifugal separators play a crucial role. Among their most popular models, the P-series and S-series separators stand out. But what exactly sets them apart? And which one is right for your needs? Let’s break it down and see the competition of P vs S Separators.
Understanding the Basics of P vs S Separators
Both P-series and S-series separators are designed to remove water, solid contaminants, and impurities from fuel and lube oil. However, they differ in operation mode, adjustability, and compatibility with different fuel types.
P-Series Separators
Purpose:
The P-series separators are designed primarily for purifying fuel and lube oil. They excel in removing contaminants and ensuring clean fuel for smooth engine performance.
Key Features:
- Operates mainly in purifier mode, separating oil, water, and sludge based on density differences.
- Utilises a gravity disc, which requires manual adjustment depending on the type of oil being processed.
- Best suited for applications with consistent fuel densities and well-defined oil types.
Common Applications:
- Marine engines using stable fuels
- Power plants
- Industrial lubrication systems
Popular Models:
- Alfa Laval P605, P615, P625
S-Series Separators
Purpose:
The S-series use Alfa Laval’s ALCAP™ technology, they automatically adjust to varying oil densities without needing manual intervention.
Key Features:
- Uses ALCAP™ system instead of a gravity disc, making it more adaptable.
- Can operate in both purifier and clarifier modes, allowing for more efficient removal of fine contaminants.
- Ideal for handling modern, low-quality fuels and high-viscosity oils.
- Automatically adjusts to different oil densities, reducing the need for manual changes.
Common Applications:
- Modern marine vessels using mixed or variable-quality fuels
- Power generation plants dealing with varying fuel compositions
- Industrial systems requiring enhanced purification
Popular Models:
- Alfa Laval S815, S825, S835
P-Series vs. S-Series: A Quick Comparison

Which One Should You Choose?
If you’re using consistent fuel types with predictable densities, the P-series offers a reliable and cost-effective solution.
If you deal with varying fuel qualities (common in modern marine and industrial applications), the S-series (ALCAP™ separators) is the smarter choice due to its automatic adjustment capabilities.
Final Thoughts
Both P-series and S-series separators serve vital roles in fuel and lube oil purification, but the best choice depends on your specific needs. If you want simplicity and reliability, go for a P-series model. If you need flexibility and automation, the S-series is the way to go.
Need help selecting the right model for your application? Contact us for expert guidance!