Direct-flow fuel filters are widely applied in carburetor and injector fuel systems. These filters have filtering elements with pleated or coiled paper partition.

As the surface of coiled filtering partition is much more than pleated, at same physical dimensions, such filtering elements are characterized by high efficiency of a filtration and in increasing frequency used in modern fuel systems.

Spin-on fuel filters that are used for diesel fuel systems also make up group of direct-flow fuel filters.

Thanks to a complex construction it is possible to combine nonseparable with “in-line” fuel filter. As distinct from “spin-on” type filters these ones have cover with welded pipes (fuel inlet and outlet).

Such filters are supplied with built-in water separator, which is necessary during diesel fuel filtration. For successful work of water separator it is necessary regularly to check it and drain gathered water.

Frequently in such constructions there are applied elements, which warm up fuel. It helps in winter to eliminate wax deposition caused by low temperature.