Inline filters: reliable component protection

Maximum use of protective filters to prevent component failures

Particle contamination is the most common cause of premature wear or catastrophic failure in expensive hydraulic components such as pumps, proportional valves, and hydrostatic drives. Positioned directly in the full flow as a highly efficient protective filter, this product family ensures the hydraulic fluid’s cleanliness class is consistently maintained.

Whether it’s to protect highly sensitive controls in machine tools, where fast, precise movements require flawless high-pressure filtration, or to withstand the continuous stresses in a paper machine: filter housings capture abrasive particles before they can cause damage. The integration of a compact protective filter doesn't just ensure continuous component protection. It also minimises unplanned system downtimes and the associated operating costs.

Inline filter with magnetic pre-filtration from the inside out

In modern engineering, those who prioritise minimising maintenance risks between services rely on a well-designed flow concept. In this groundbreaking series, fluid flows through the filter element from the inside out.

The key advantage for maintenance managers and design engineers: during element replacement, the trapped contamination particles remain entirely inside the filter element and do not return to the circuit. This boosts process reliability by ensuring a quick replacement without any risk of re-contaminating the system. At the same time, this flow direction provides the physical foundation for a highly effective magnetic core integrated into either the cover or the element spigot. This captures ferritic particles before they reach the actual filter material, significantly reducing the strain on the glass fibre or wire mesh and dramatically extending the overall system's service life. An optional bypass valve also provides reliable protection for the system during cold starts or extreme viscosity fluctuations.

Validated safety for the highest standards

For test engineers, quality managers, and technical procurement specialists in heavy industry, only verifiable and reproducible quality counts. Our filter elements are rigorously validated according to international standards and undergo continuous quality monitoring. This includes:

ISO 2941 (testing of resistance to collapse and burst pressure)
ISO 2942 (proof of satisfactory manufacturing quality / bubble point test)
ISO 2943 (verification of material compatibility with fluids)
ISO 3968 (determination of flow characteristics and differential pressure)
ISO 11170 (testing the performance characteristics of hydraulic filter elements)
ISO 16889 (multipass test method for determining filtration performance)

Thanks to these strict validation limits, compliance with precise filtration ratings from 5 µm(c) is guaranteed throughout the element's service life. The housings offer flexible connection options for visual and/or electrical clogging indicators, which proactively signal the optimal maintenance time before the bypass valve opens.

Cast design and welded design in a system comparison

To meet the challenges posed by limited installation space, varying pressure ranges, and fluctuating flow rates in mechanical and plant engineering, the product range is divided into specialised component groups. Depending on the requirements, either a robust weld design or a flow-optimised cast design is used.

Welded designs for extreme flow rates (DMX series) are required
when large quantities of fluid need to be cleaned in low-pressure lines or large-scale test bench applications: "welded inline filters for high flow rates" are what is needed here.

Specifications: the DMX series is manufactured in five sizes (0400 to 1200). It can handle flow rates of up to 1,200 litres per minute and has a pressure resistance of up to 25 bar. This welded design, with SAE flange ports and a sturdy mount, features space-saving integration despite its high-performance capabilities. The element can be easily removed from above and the housing comes with an oil drain plug as standard.

Cast designs for universal use (series DMP, DMG, DNG)
offer maximum dimensional stability and cost-effectiveness for standardised installation spaces and varying medium-pressure ranges, thanks to their classic cast design. Design engineers often look for solutions such as the following in this context: "Hydraulic cast inline filters for medium pressure."

DMP series: Designed for the low-pressure range up to 25 bar and flow rates up to 700 l/min. The housing cover opening located at the top makes it ideal for easy servicing.
DMG/DNG series: The housing is made of high-strength material (EN-GJS/spheroidal graphite iron) and can withstand operating pressures of up to 120 bar (DMG) or 25 bar (DNG), with flow rates of up to 250 l/min. These components excel due to their superior flow geometries and minimal inherent pressure differentials.

High-pressure pressure filters and compact protective filters (DMH, DSR/DSK series)
For direct installation in the high-pressure line downstream of the pump, a dedicated pressure filter is mandatory to fully protect downstream system components.

DMH series: Designed as a robust pressure filter capable of withstanding extreme loads of up to 250 bar nominal pressure and flow rates of up to 250 l/min. It effortlessly withstands dynamic pressure spikes in the system.
DSR/DSK series: If you're looking for an ultra-compact solution that can be used over the system's entire service life, check out the product under the search term "protective filter with screw connection for hydraulic lines, 250 bar". These inline filters feature a permanently installed filter element made of durable wire mesh (WCO), operate at pressures up to 250 bar (up to 70 l/min), and are directly integrated into the line – making them ideal for extremely tight installation spaces.

Technical data at a glance

Filter series	Design type	Max. flow rate	Max. operating pressure	Primary application
DMX 0400–1200	Welded design	1,200 l/min	25 bar	High flow rates, low pressure, test benches
DMP 0200–0700	Cast design	700 l/min	25 bar	Full-flow filtration, test bench applications
DMG 020–250	Cast design	250 l/min	120 bar	Medium-pressure applications, mobile & industrial hydraulics
DNG 020–250	Cast design	250 l/min	25 bar	Standard low-pressure circuits, component protection
DMH 045–250	Cast design	250 l/min	250 bar	High-capacity pressure filter for high-pressure lines
DSR 020–050 / DSK 060	Compact housing	70 l/min	250 bar	Compact protective filter for direct line connection via screw fitting