Given that a filter may not be able to remove all of a suspended solid, there will, nevertheless, be a particle size cut-off point above which no particle should be able to pass through the filter. The cut-off point thus refers to the diameter, usually expressed in micrometres (m), of the largest particle that will […]
Filters are rated according to their ability to remove particles of a specific size from a fluid suspension. There are many different methods in which performance may be specified in this way, and quantitative information as to filter performance must always be associated with the corresponding test methods used. The object of a filter is […]
It has been stated that a filter medium is a porous (or at the very least semipermeable) barrier placed across the flow of a suspension to hold back some or all of the suspended material. If this barrier were to be very thin compared with the diameter of the smallest particle to be filtered (and […]
The basis of the particular mechanical separator that is called the filter is the placing across the fluid flow of a barrier, the filter medium. This acts like a porous screen, allowing those arriving particles – which are below a certain size – to pass through the openings that give the medium its porosity, together […]
Contaminants will enter liquid flows from their environment and from any prior treatment or contamination that they have undergone. The prime concern over liquid contamination now and into the foreseeable future is the provision of drinking water free of harmful bacteria and viruses, a provision that is still unavailable to vast areas of the world. […]
As shown in Figure 1.1 , airborne particles may range in size from 1 nm (0.001 um) up to 1 mm or more. The larger particles, such as might come from heavy foundry dust or ground limestone, would need updrafts of the order of 4 or 5m/s to maintain them in suspension. For the very […]
The critical factor in the creation and maintenance of dust-laden air or particle contaminated water is the nature of the particle, in terms of its size and its relative density. This is because of the development of a constant, terminal velocity by a particle falling freely through a fluid, whose value, as demonstrated by Stokes […]
Contaminants, i.e. minor impurities, are normally present in all fluids, natural or processed. Where the level of contamination in the fluid is significant, i.e. too great for that fluid to be consumed, or used for its proper purpose, or to be subsequently processed, then it becomes necessary (or in some cases legally obligatory) to remove […]
At the time of writing, there is much concern being expressed about the global environment and human influences upon it. Whether it is to do with climate change and its probable human cause; continued starvation in large regions of an otherwise rich world; or the conversion of a runaway consumption to a sustainable expansion, large […]
There is hardly a human activity, industrial, commercial or domestic, that is not affected by filtration. It is a very widely used process, from the kitchen counter top water filter to the enormous wastewater treatment plants, or from the delicate membrane ultrafilter to the rugged tipping pan filter of a mineral processing works. It has […]
