Selection and calculation principle of the filter
1. Filter Introduction
1.1 The filter use position and purpose, can be divided into two categories: a coarse filter (English strainer) and fine filter
Coarse filter before the pump is mainly used, flow meters, valves, to protect equipment from large metal particles are milled, the basic accuracy of a few hundred microns. Fine filter is mainly fluid purification, process safety protection. Its accuracy range substantially between 1 to 30 microns.
1.2 design requirements can be divided according to the manufacturer: pressure vessels and non-pressure vessels
A pressure vessel design and manufacture of the filter housing or ASME Executive GB150 standard. Non-implementation of the pressure vessel SH / T3411 or HGT 21637 standards.
1.3 Depending on the media can be divided into: gas filters and liquid filters
Gas filters suitable for gas - solid separation basin can be used for gas purification, into recycling. Liquid filter applied to liquid - solid separation, such as lubricating oil filter, oil and chemical industry, filtration and wastewater treatment.
2. The fine filter area:
Coarse filter has three domestic industry standards, so just follow the selection criteria can meet the requirements.
Fine filter filter area calculation formula calculation does not substantially, when the election is to form the main basis of experimental data, therefore, choose the recommended filters or let manufacturer to choose.
Three filter curve:
Differential pressure flow curve (ΔP-Q), and the filter diameter ratio curve (μ-β), and the pressure time curve (T-ΔP)
Therefore, when calculating the filter area should be based on three curves, the most important is the flow differential pressure curve, this curve by the strength of the filter factory test measured.
The most authoritative test is repeated by the test: ISO 4572 standard multi-pass test. This test stand is expensive, there are only 2-3 units currently. At present, the company's small manufacturers filter cartridge is detected by a single experiment.
Filter area calculation step:
1. Determine the filtration accuracy of 25 micron filter ratio, such as 200 (filtration efficiency), to determine when the filter
The given pressure drop 0.05MPa, to filter traffic pressure test. Obtain appropriate flow rate (L / min)
3. The resulting flow rate, divided by the area of ??the test filter, calculated flow rate (L / min.m2).
4. The flow rate and flow of practical application, to determine the filter area, flow / flow rate = filtration area
5. Determine the filter in the form of structure, folding or winding type cylinder according to the chosen filter area and filter