Filtration Devices

Filtration is the technique where a pressure gradient generated across a filter is used for the separation of solids from fluids (liquids or gases) by interposing a medium through which only the fluid can pass. Filtration is an important tool used in many biological and chemical laboratories; applications include water treatment, air purification, and coffee percolation. The pressure gradient can be created with many methods including gravity flow, vacuum pressure, high pressure, and centrifugal force. The filter devices in this section are separated into bottle top units, concentrators, membranes, plates, self-contained units and ultrafiltration devices. When choosing a method it is important to consider the total sample volume- for example sample greater than 10ml work well with gravity filtration; smaller volumes may require vacuum pressure or centrifugal force. Particle size distribution an important factor for filter choice- micron size (µm) indicates the pore size of the filter of which anything smaller will pass through. Liquid viscosity and density and particle size and charge are also important factors to investigate when choosing an appropriate filter.