Glossary
The language of filtration, plainly.
Short, accurate definitions for the day-to-day vocabulary of industrial filtration. Each term links to the product categories it touches.
Micron rating
The smallest particle size a filter can capture, measured in microns (μm). 1 micron equals 0.001 mm. A lower number means finer filtration: a 5-micron filter is tighter than a 25-micron one.
Related categories:Oil FiltersFuel Filters
Beta ratio (β)
An efficiency measure for hydraulic filters: the ratio of particles larger than X microns at the inlet to those at the outlet. β10 ≥ 200 means more than 99.5 % of particles above 10 µm are retained.
Related categories:Hydraulic Filters
Bypass valve
A safety valve that opens when a filter is clogged or oil is cold enough to spike differential pressure. When it opens, oil bypasses the filter, keeping the engine lubricated, but filtration stops until pressure drops.
Related categories:Oil FiltersHydraulic Filters
Anti-drainback membrane
A rubber membrane that prevents oil from draining out of the filter back to the sump after engine shutdown. On restart it lets oil pressure build instantly, avoiding a dry start.
Related categories:Oil Filters
Cyclonic pre-cleaner
A device that spins incoming air so centrifugal force separates coarse dust before it reaches the main filter. In dusty conditions it can extend air filter life by an order of magnitude.
Related categories:Air Filters
Differential pressure (Δp)
The pressure drop between a filter's inlet and outlet. As the filter loads, Δp rises; once it crosses the threshold the bypass valve opens or the change-indicator triggers.
Related categories:Hydraulic Filters
AdBlue (urea solution)
A 32.5 % urea / 67.5 % deionized water solution injected into the SCR systems of Euro VI diesels. It reduces NOx emissions and must conform to ISO 22241 purity.
Related categories:AdBlue Filters
OAT / HOAT coolant
Organic acid technology (OAT) and hybrid organic acid technology (HOAT) are long-life coolant formulations. They offer much longer service intervals than legacy IAT coolants and don't require DCA supplements.
Related categories:Water Filters
SCR system
Selective Catalytic Reduction injects AdBlue into the diesel exhaust to convert NOx into nitrogen and water vapor. It is mandatory for Euro VI compliance.
Related categories:AdBlue Filters
Molecular sieve desiccant
A synthetic crystalline material with very small uniform pores used in air dryer cartridges. It selectively adsorbs water vapor and delivers dry air to the pneumatic system.
Related categories:Air Dryer Filters
Spin-on filter
A single-piece closed-canister filter design. At service the old can is removed and discarded, and a new one is fitted. Common in oil, fuel, and hydraulic systems.
Related categories:Oil FiltersFuel Filters
OE specification
The Original Equipment Manufacturer's complete engineering spec for a part: dimensions, materials, micron rating, valve settings. Filter selection always references the OE spec, not just dimensions.