Hydac MFM Inline Pressure Filter, up to 280 bar and 100 l/min

Compact 280 bar inline filter with a choice of port threads

The Hydac MFM is a compact inline filter for mobile and machine hydraulics up to 280 bar. It has a ductile iron head and a screw-in steel bowl, and the filters are supplied phosphated and primed. Four sizes, MFM 35, 55, 75 and 95, handle flows up to 100 l/min.

Metric ports (M18 x 1.5, M22 x 1.5) and G threads (G1/2, G3/4) are offered, plus two head layouts, which makes it easy to fit into existing manifolds and brackets.

Technical specifications

Order code and mounting options

The example in the datasheet is MFM ON 55 O D 10 D 4 .X /-L24-B7. The fields are type, element material, size, pressure letter O (280 bar), connection letter, micron rating, indicator letter, type code (3 or 4) and supplementary details such as the 7 bar bypass (B7), lamp voltage or LED, FPM seals and HFA or HFC suitability. Brackets for side mounting are listed as WAL (inlet on left) and WAR (inlet on right) for type code 4 only.

The replacement element for this size is coded like 0055 D 010 ON, and the indicator is the VD type with a 5 bar setting.

Points to confirm

Check the port thread (metric against G) and the head layout, since type code 3 and 4 differ in indicator position and the number of mounting holes. Earth the housing and de-energise before removing an electrical indicator connector.

Compatible fluids are hydraulic oils H to HLPD, lubrication oils, compressor oils and biodegradable HETG, HEES and HEPG; high-water-content fluids on request. State the pressure of your circuit so the indicator type can be matched to it.

For sizing, the gradient coefficients in mbar per l/min at 30 mm2/s are given per size and micron rating. Optimicron elements in MFM 35 are listed at 13.7 at 10 µm and 7.44 at 20 µm, and in MFM 55 at 7.90 and 3.84. The small body therefore costs more differential pressure per litre than a larger one, so size up where flow is close to the 100 l/min limit.

Gradient coefficients for Optimicron elements, in mbar per l/min at 30 mm2/s:

How the Hydac MFM inline filter works

An inline pressure filter sits in the pressure line of a hydraulic circuit and cleans the oil before it reaches valves, cylinders or motors. The oil enters the head, passes through the element from the outside to the inside, and leaves cleaned. Dirt stays in the element, and the pressure drop across it rises as the element loads up. The MFM has a bypass with a cracking pressure of 7 bar, so oil can still flow if the element is blocked, and a VD clogging indicator set at 5 bar warns the user that the element needs a change.

Where the MFM is used

• Mobile machines and construction equipment.
• Machine tools and presses.
• Hydraulic power units with limited space.
• Circuits that need protection for sensitive valves.
• Systems up to 280 bar and 100 l/min.

Selection checklist for the MFM

• Size: MFM 35, 55, 75 or 95, from the flow rate.
• Nominal pressure of 280 bar.
• Filtration rating of 1, 3, 5, 10, 15 or 20 micrometre.
• Connection: M18 x 1.5, G1/2, M22 x 1.5 or G3/4, by size.
• Head layout, type code 3 or type code 4.
• Clogging indicator: type and electrical connection.
• Seal material, NBR as standard and FPM as an option.
• Temperature range of -10 to +100 degrees C.
• Bracket for side mounting, where needed.

Installation, commissioning and maintenance notes

Install the filter so the flow direction matches the arrow on the head, and leave space below the bowl for element removal. Before opening the bowl, release the system pressure and let the oil cool. Change the element when the indicator shows, or at the interval set by the maintenance plan, and replace the O-ring at the same time. Dispose of used elements and oil as the site rules require.

Requesting a quotation for the Hydac MFM

Send the flow, the pressure, the port thread and the filtration rating. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

Bypass and indicator

The bypass protects the pump from starvation, while the indicator tells the operator when to act. Use both together for a safe filter.

Reading the order code

The order code lists the type, element material, size, pressure letter, connection, micron rating, indicator and head layout, so check each field before ordering.

Maintenance records

Write the element code and the change date on the machine service sheet.

Cleanliness of hydraulic oil

Most hydraulic failures start with dirty oil. Particles wear the sealing edges of valves and cylinders, and they make spools stick. A filter with the right rating, checked at regular intervals, protects these parts and extends the life of the whole circuit.

Fatigue strength of the housing

The data sheet gives a fatigue strength of at least 10 million cycles from 0 to 280 bar, which suits machines with frequent pressure changes.

Spare element planning

Keep a spare element of the correct code on the shelf, so a clogged filter can be changed during the next stop without waiting for delivery.

Documents and quotation

The datasheet (E 7.556.6/11.16) is attached. Related: filter housings and the Hydac RFM return line filter.