Hydac MDF Medium-Pressure Inline Filter, up to 280 bar

Ductile iron inline filter for 280 bar systems

The Hydac MDF is a medium-pressure inline filter with an EN-GJS-400-15 head and a screw-in steel bowl. Five sizes, MDF 30 to MDF 240, cover flows up to 280 l/min at a nominal pressure of 280 bar. Typical positions are pump outlets and the supply line ahead of proportional or servo valves.

The standard model has no bypass valve, a port for a clogging indicator and mounting holes in the head. The fatigue rating is at least five million cycles at 1.2 times the nominal pressure.

Technical specifications

Order code and options

The sheet’s example is MDF ON 60 O C 10 D 1 .X /-L24. After MDF come the element material, size, pressure letter O (280 bar), connection letter, micron rating, clogging indicator letter and type code. Indicator choices are A (steel plug), B (visual), C (electrical) and D (visual and electrical). Optional extras in the datasheet are the head-integrated bypass, an oil drain plug, FKM seals and test certificates.

Fluids listed as compatible are hydraulic oils HL to HVLP, lubrication oils, compressor oils, biodegradable HETG, HEES and HEPG, and fire-resistant HFA, HFB, HFC and HFD to ISO 12922. High-water-content fluids are available on request.

What to confirm before ordering

Check the pressure class of the circuit against 280 bar, including peaks, and decide whether a bypass is acceptable. A bypass protects the pump from a clogged element but lets unfiltered oil through, so some servo applications specify none. The housing must be earthed, and the power to an electrical indicator should be switched off before the connector is removed.

For higher pressures look at the DF series, and for reversible flow use a DFF. Send the old filter’s nameplate code with your enquiry so we can match connection, micron rating and indicator type.

The datasheet’s sizing section lists gradient coefficients in mbar per l/min for mineral oil at 30 mm2/s. Optimicron elements in MDF 110, for instance, are given as 13.40 at 3 µm, 9.61 at 5 µm, 6.06 at 10 µm and 2.99 at 20 µm. Finer elements cost more differential pressure, so choose the coarsest rating that still meets your cleanliness target and allow for viscosity at cold start.

The datasheet limits the flow per size and connection, because exceeding it can destroy the element:

Gradient coefficients for Optimicron elements at 10 µm run from 22.80 mbar per l/min on size 30 to 3.19 on size 240.

How the Hydac MDF works

The MDF is a pressure filter that sits in a hydraulic line. Oil enters the head, flows through the filter element from the outside to the inside and leaves clean. Particles are held in the element material. As the element fills, the pressure drop across it rises. The clogging indicator senses this rise and shows or signals when the element needs changing. The strong ductile iron head and steel bowl carry the full system pressure of 280 bar.

Where the Hydac MDF is used

• Pump outlets in hydraulic power units
• Supply lines ahead of proportional valves
• Supply lines ahead of servo valves
• Mobile and industrial machinery
• Test stands and presses

Selection checklist for the Hydac MDF

• Size from MDF 30 to MDF 240
• Flow rate up to 280 l/min
• Element material: ON, BH/HC or wire mesh
• Filtration rating in microns
• Port thread G1/2, G3/4 or G1 1/4
• Clogging indicator type
• Bypass valve or none
• Seal material NBR or FKM

Installation, commissioning and maintenance notes for the MDF filter

Mount the filter with the bowl pointing down and leave space to unscrew it. Connect the ports in the flow direction marked on the head. Fit the indicator and check its setting. Watch the indicator after start-up. Change the element when it signals, check the seals and refit the bowl.

Requesting a quotation for the Hydac MDF

Please send the flow rate, the pressure, the fluid, the micron rating, the port size and the quantity. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

MDF pressure and fatigue rating

Nominal pressure is 280 bar. The fatigue rating is at least five million cycles at 1.2 times nominal pressure.

MDF element materials

Elements come in Optimicron, Betamicron or stainless steel wire mesh.

MDF compatible fluids

The sheet lists mineral hydraulic oils, lubrication oils, biodegradable fluids and fire-resistant fluids.

MDF weights

Weight with element runs from 2.3 kg for MDF 30 to 11.7 kg for MDF 240.

MDF temperature range

The range is minus 30 to plus 100 degrees C, limited to 140 bar below minus 10 degrees C.

Filter records for the MDF

Record the element code, the change date and the indicator status.

Choosing the right MDF size

Choose the size from the flow rate and the dirt capacity needed between changes.

Documents and quotation

The datasheet (EN 7.502.5/12.19) is attached. Related: filter housings and the Hydac SB330 bladder accumulator.