Purafix
Depth filter sheets are used to remove particles from liquids. This means that liquids can be clear-, fine-, or sterilization-filtered. For depth filtration, filter media of a thickness of 2.5–4.5 mm are required. The particles are retained using two filtration principles:
- Surface filtration
- Depth filtration
The liquid flows through a three-dimensional, asymmetrical fiber network in the depth filter. The solid components are retained using mechanical and electrokinetic effects, which significantly increases the absorption capacity. The purpose of a filtration process is to produce either a liquid (filtrate) or solids (retentate). Depth filtration focuses mainly on the production of liquid filtrate. Formats are available from 6 cm round to 2.425 m x 1.215 m square. Practically every format in between is possible, which means they can be installed in any commercially available sheet filter. Depth filter sheets have a particle absorption capacity of up to 4 kg/m². Furthermore, any available filter sheet grade is available as a lenticular module (FILTRODISC™, see brochures for DISCSTAR® and FILTRODISC™ modules). PURAFIX® depth filter sheets have been specially developed for use in critical applications such as the processing of biopharmaceutical products. They are characterized by their extremely low levels of ions and pyrogens.
Material
- Cleaned and bleached cellulose
- Natural filter aid (kieselgur, perlite)
- Cationic wet strength agent
Handling
Depth filter sheets are used in sheet filters such as those in the FILTROX NOVOX® range. The sheets (except with NOVOX® OD) must be wettened when fitted into the filter and should be prerinsed with 50 l/m² of clean water/buffer for industrial applications and for use in the drinks industry. The pressure difference between the inflow and outflow guarantees a constant flow. The filters are exhausted when the differential pressure exceeds a given value (1–2.5 bar, depending on porosity and application). With certain applications, it is possible for the filter to be regenerated. Please note the special instructions for this purpose. The sheets can be sterilized with hot water (85 °C) or inline steam (125 °C).
