Partial flow filtration is used where there is a requirement for continuous flow, also during filter cleaning. Efficient removal of dirt and magnetic particles from the liquid reduces the number of breakdowns in the system and increases the life of measuring equipment, heat exchangers, pumps, valves and other components significantly.
In partial flow filtration, 5-15% of the total flow is led out of the system and pumped through the magnetic/bag filter, and is then led back to the system –cleaned of sludge and magnetite. As the partial flow filter is not located in the main circuit, the flow through the filter can be interrupted and the filter cleaned without interrupting the main flow.
Continuous reduction of the sludge content reduces sedimentation in heat exchangers, pipes and other components, helping to keep heat transmission performance at a maximum and reducing corrosion in the system. An error indication in mechanical measuring equipment and errors in connection with inductive measuring is also minimised, which is why it is possible to achieve more reliable energy consumption measurements.
The magnetic bars in the filter are located in conducting pipes which lead the liquid through a magnetic field generated by magnets with changing polarity. This induces a field around even the smallest particles and so provides efficient retention of particles of less than 1 micron. The filter will actively retain ferromagnetic particles and some iron oxides of the Fe3O4, g-Fe2O4, d-Fe2O3type and other mixed oxides of Fe3O4, where the spinel structure FeO is substituted by other oxides, e.g. CoO, MnO, NiO, ZnO, Cr2O3.
Non-magnetic particles are retained efficiently in the filter bag. (See also data sheet for filter bags).
Capacity: 2,4 – 210 m3/h
Filtration: 1 – 100 µm
Pressure: 10 – 16 bar
How much should be filtered:
Normally 5-15% of the flow through the mainline should be filtered. In transmission systems that are characterised by a limited amount of circulating liquid and a relatively high liquid flow rate filtration of 3-5% of the main flow will be sufficient. Transmission systems are mostly isolated circuits where contamination is relatively limited.
In distribution networks filtration of around 5-10% will be sufficient to protect the system if it is of a more recent date and the filter is installed when the system is started up. If partial flow filtration is installed in an older system where partial flow filtration has not previously been used 10-15% should be filtered to achieve a satisfactory result.
Where should the partial flow filter be installed:
The partial flow filter should preferably be installed in the return pipe. This is where the temperature is lowest which increases the efficiency of the magnets. Magnets lose approximately 0.2% of their efficiency with each temperature increase of one degree Celsius.
The filter unit should be placed in the lower part of the system as particles precipitate and accumulate here. Dirt has a tendency to move in the system during start-up and when the flow is changed as a result of regulation or pressure surges. It should therefore be expected that the filter will fill with dirt faster on these occasions.
When connecting the partial flow unit to the mainline it is vital that the connection to the inlet side of the unit is fitted at the bottom of the mainline. This is because the dirt particles move along the bottom of the pipe. The connection should also be installed where the flow of liquid in the mainline can be expected to be laminar. This means that the outlet from the mainline to the unit should be located at least 8 to 10 times the pipe diameter of the mainline from either a bend, valve or other
Design and production:
HiFlux Units are manufactured in a number of different versions of which the standardised units are shown on the following pages. All units accommodate current standards and norms for pressure vessels, conform to the EMC Directive and are CE-labelled. Approval in accordance with the Danish Working Environment Service, TüV, UDT etc. is possible. Filters of pressure class PN16 are manufactured in container steel with full traceability and continuos process control has been carried out. EN 10204 3.1.B material certificates, NDT report from welding test and check books are supplied in accordance with the official requirements of the place of use or as agreed.
Special versions can be made in co-operation with our design department.