ABSOLUTE FILTERS DUAL FILTERS Model OW
Sizes 20mm (3/4”) - 200mm (8”)
For applications where the requirement is for continuous flow with minimum loss of pressure, the dual filter provides quality of design and performance.
The filter is of cast construction and incorporates two chambers each containing a high quality stainless steel basket. Flow is diverted from one basket to the other without being interrupted by simply turning the handle which rotates dual cylindrical cocks.
- Simple changeover operation, requires infrequent maintenance.
- Compact design.
- Large filtration areas giving low pressure drops.
- Quick release filter covers and knobs for easy maintenance. No contamination between filtered and unfiltered liquids.
- Wide range of materials, sizes and accessories. Filtration down to 10 microns.
- Handle covers chamber in use - preventing accidental opening of pressurised chamber.
- Differential pressure indicators shown in photograph are optional extras.
PRESSURE DROP CHART
The chart is for water flowing through a filter without an element. Use the correction factors shown on page 10 for the chosen filtration rating and liquids of higher viscosity
EXAMPLE - OW FILTERS:
A dual basket OW filter is required to filter particles the size of 80 microns from lubricating oil which has a viscosity of 230 centistokes at 40°C. The flowrate of oil is 150 litres/min at a pressure of l0 bar g.
A clean basket pressure drop of no more than 41 Kpa is acceptable
- Check temperature/pressure rating of filter and suitability for application, i.e. 40°C temperature at 10 bar g: Standard Cast lron Filter suitable.
- Selection of Mesh: Protection to 80 microns or less would require a 200 mesh basket. (See Standard Basket Data)
- Mark flowrate of 150 litres/min on chart 2 to intersect diagonal “filter selection line” and read vertically to obtain pressure drop in Kpa.
150 litres/min intersects 50mm (2//) - 65mm (21/2//) filter and will have a pressure drop of 5.5 Kpa.
- Apply correction factor for oil at 230 centistokes with 200 mesh lined basket: (see page 10)
Pressure drop = 5.5 Kpa x 3.75 = 20.6 Kpa
(This falls within acceptable pressure at 41 Kpa)
- Selection for application would be 50mm (2//) or 65mm (21/2//) cast iron OW filter with a 200 mesh lined basket.
STANDARD BASKET DATA FOR OV AND OW
Baskets are constructed from stainless steel perforated plate. The relevant degree of filtration is provided by welding the appropriate grade of stainless steel mesh to the basket. Pleated elements giving filtration down to 10 microns are also available.