Hydac OLF 5 Offline Filter for Hydraulic and Lube Oil

Hydac OLF 5 offline filter series for fine filtration of hydraulic and lube oil

The Hydac OLF 5 is the smaller of the HYDAC OffLine Filter (OLF) series. Instead of filtering the oil in the main circuit, an offline filter takes a small flow from the tank, pushes it through a fine element and returns it to the tank. Because the offline circuit runs continuously and independently of how hard the machine works, the oil is cleaned in a steady, gentle way even when the main circuit is at rest, and the main-line filters have less dirt to catch. The OLF 5 and 10 data sheet covers a family of versions with or without a motor-pump unit, with flow rates up to 15 l/min and viscosities up to 7,000 mm²/s. Seven Star LLC supplies Hydac products in Oman and the GCC as an independent supplier in Muscat.

OLF 5 technical specifications

Reading the OLF 5 model code

The data sheet shows a code of the form OLF – 5 – S – 120-N – N5DM002 – E / -7.5. OLF is the offline filter; OLFCM adds fluid condition monitoring and is available only with size 5/15, 10/15 and the toploader. The number gives size and flow: 5 for 5 l/min, 5/4 for 4 l/min for lubrication, 5/15 and 10/15 for 15 l/min, and 5/Z or 10/Z for a filter without drive. The letter gives the version: S standard with motor, E with flow control valve and no motor (fed from a 10 to 50 bar line), T toploader with or without motor and F filter only.

The motor code then selects the electrical supply, for example 120-N for 120 W three-phase 400 V 50 Hz, 120-M for 230 V single phase, 120-K for 120 V 60 Hz, 370-N, -M and -K for the same voltages at 370 W, or 200-U for 24 V DC. The element code reads N 5 DM 002, which is size N5, Dimicron and 2 µm absolute. A final letter selects the clogging indicator, such as a back pressure gauge or a differential pressure indicator, and supplementary letters add a ContaminationSensor (CS 1310 or 1320) and AquaSensor.

How an offline filter circuit works

A motor-driven vane pump draws oil from the tank through the inlet, pushes it through the element in the filter bowl, and returns the clean oil to the tank through the outlet. A clogging indicator on the housing shows when back pressure reaches the limit and the element must be changed. In the E version, there is no motor; the unit uses a flow control valve and takes its flow from a system line at 10 to 50 bar, which suits machines that already have a pressure supply. Fine filtration at 2 or 5 µm is practical here because the flow is small, so the element can be fine without a large pressure drop.

The Aquamicron element absorbs water as well as particles. For plants where water ingress is the main risk, such as turbine lube oil in humid coastal sites, the water-absorbing element is the version to discuss. The data sheet lists a water retention of about 0.25 l for N5 and 0.5 l for N10 elements.

Where OLF 5 fits in a hydraulic system

The OLF 5 is for small and mid-size reservoirs: the data sheet gives application ranges by flow, with the OLF-5/4 serving tank volumes up to about 300 l, the OLF-5 up to about 800 l and the OLF-5/15 up to about 2,000 l. The larger OLF 15, 30, 45 and 60 series cover bigger tanks, and the CS 1000 ContaminationSensor can be added to monitor results. Typical users list machine tools, plastic injection machines, mobile and stationary hydraulics and wind energy; in our region, the same logic applies to hydraulic power units on valve actuators, gearbox lubrication and press systems.

Selection and ordering checklist for OLF 5

• Tank volume and oil type, to select the flow (4, 5 or 15 l/min) and viscosity range at the lowest temperature.
• Version: S motor unit, E without motor on a pressure line, T toploader or F filter only.
• Electrical supply and frequency for the motor.
• Element type: Dimicron or Aquamicron, and absolute rating from 2 to 20 µm.
• Seal material: NBR or FKM for the fluid in use.
• Clogging indicator type and whether a ContaminationSensor or AquaSensor is needed.

Installation and maintenance of OLF 5 filters

Mount the unit so that the inlet draws from the tank below the minimum oil level, keep the suction line short and avoid air leaks, because the vane pump only tolerates inlet pressure between -0.4 and 0.6 bar on the S versions. Return the oil below the oil level, away from the suction point, so the same oil is not cleaned again straight away. Leave the minimum clearance for element removal shown in the dimension drawing. Change the element when the clogging indicator reaches the limit, or at the interval set by oil analysis, and dispose of used elements through incineration, as the data sheet notes they are environmentally safe to burn. Keep spare elements and seals for each unit.

OLF 5 applications in Oman and the GCC

Hydraulic power units for valve actuators, tank farm equipment, turbine and compressor lubrication, and mobile equipment working in hot dusty conditions are all targets for offline filtration. High ambient temperatures reduce oil viscosity, and the limit on fluid temperature is 80°C for these units. Humidity and sand ingress through breathers raise water and particle levels, so combining offline filtration with a breather filter on the tank is a common practice.

Information to send with an OLF 5 RFQ

• Tank volume, oil grade and operating temperature range.
• Required cleanliness code and whether water removal is wanted.
• Power supply voltage and frequency.
• Full model code if known, or preferred model part number.

Documents and quotation

The Hydac OLF 5 data sheet is attached on this page, including the technical data, model code and dimensions.

Send the tank and electrical details and Seven Star LLC will confirm the right OLF 5 version and quote supply to Oman and the GCC.