Hydac SF, SFM and SFF Suction Filter, up to 500 l/min

Suction filters that protect the pump inlet

The Hydac SF series protects a pump from coarse contamination on the suction side. The range covers three housing types and a set of screw-in suction elements: SF is an aluminium housing with a bolt-on cover plate, SFM adds a head and a polyamide bowl, and SFF has a steel bowl with a foot valve in its base.

Flow goes up to 500 l/min, and every housing includes a bypass valve and a connection for a clogging indicator. Suction filters work under negative pressure, so mesh size and installation depth matter more than they do on a pressure filter.

Technical specifications

Order code and screw-in suction elements

The datasheet example is SF W 330 W L 10 UE 1 .X /-V, which combines the type (SF, SFM or SFF), the material (P paper, not for SFF, or W wire mesh), size, operating pressure letter W for suction operation, the connection letter, the rating and an indicator letter. The indicator choices are A (screw plug), UE (negative pressure gauge) and UF (negative pressure switch). Supplementary details cover omission of the bypass valve (KB), FPM seals (V) and suitability for HFA and HFC (W).

Replacement elements for the housings are coded like 0330 RS 075 W, with SFF added to the code for SFF filters. Separate S elements (S, SH, SU and SG) are designed to screw directly into the pump’s suction line, and are also offered for mounting on the outside of the tank on devices with hoses that see little mechanical load.

Installing suction filters correctly

Suction elements must always be installed well below the minimum oil level, or the pump can draw air. Because the pump pulls oil through the element, a clogged filter shows up as falling pressure after the element, which is why the vacuum indicators are used. Respect the 0.2 bar bypass setting; asking for a different bypass or none at all changes how the pump is protected.

Compatible fluids are hydraulic oils H to HLPD, lubrication oils, compressor oils, biodegradable HETG, HEES and HEPG, and fire-resistant HFA to HFD, with high-water-content fluids on request. Send the old filter code or the pump inlet size, the viscosity range and the micron rating you want.

The three housing types differ as follows:

How the Hydac SF suction filter works

The Hydac SF sits in the suction line, or inside the tank, in front of the pump. Oil is drawn through a wire mesh or paper element from the outside to the inside, and the coarse particles stay on the element. The filter works under negative pressure, so the bypass valve opens at only 0.2 bar if the element clogs. This protects the pump from starving of oil. A clogging indicator, such as a vacuum gauge, shows when the element needs service.

Where the Hydac SF is used

• Pump inlets in hydraulic power units
• Tank-top installations
• Inline suction lines
• Machines that run on mineral oil
• Systems with HFA or HFC fluids when the option is chosen

Selection checklist for the Hydac SF

• Housing: SF, SFM or SFF
• Flow up to 500 l/min
• Element: paper or wire mesh
• Mesh of 75 or 125 micron, or paper of 10 or 20 micron
• Connection thread or SAE flange
• Indicator: screw plug, gauge or switch
• Seals in NBR or FPM
• Bypass valve or omitted bypass

Installation, commissioning and maintenance notes for the Hydac SF

Fit the filter as close as possible to the pump inlet and below the oil level, so that no air is drawn in. Check that the suction line is tight, because air leaks cause noise and foam. Look at the indicator when the oil is warm. Change or clean the element when it shows, and check the seals. The temperature range is minus 10 to plus 100 degrees C.

Requesting a quotation for the Hydac SF

Please send the flow, the oil, the mesh size, the connection and the quantity. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

Hydac SF housing materials

The SF has an aluminium housing. The SFM has an aluminium head and a polyamide bowl. The SFF has a steel bowl with a foot valve in the base.

Hydac SF element construction

The element has polyamide end caps and a zinc-plated steel centre tube. Pressure stability is 5 bar for both paper and wire mesh.

Hydac SF order code

The code lists the type, the material, the size, the letter for suction operation, the connection, the rating and the indicator.

Hydac SF screw-in elements

Separate S elements are designed to screw directly into the pump suction port.

Filter records for the Hydac SF

Keep the element change dates and the oil condition in the maintenance file.

Choosing the right Hydac SF housing

Choose the housing by flow and by whether the filter sits on the tank or in a line.

Documents and quotation

The datasheet (E 7.406.3/11.16) is attached. Related: filter housings and the Hydac RFM return line filter.