Filter Media, Binderless Glass Microfiber
Depth filtration categorizes filter media that traps particulate within the random matrix of fibers found within the thickness of the media. The efficiency rating of the filter is characteristic of the complex void space structure that develops as the fibers overlap. The fibrous material within the filter is commonly glass microfiber, cellulose or polypropylene. In depth filters using glass microfiber, the purity of the filter is dictated by the presence of, if any, binder material that acts as a strengthening agent and aids in holding the fibers together. All the media described on this page are 100% borosilicate glass and free of binders.
Because of the characteristically high flow rates of depth filters, they are generally used in applications such as single and multi-process removal of sediment and coarse particulate. Glass microfiber filters without binders are an ideal medium to entrap sediment for further analysis and counting due to the inert matrix. Also, depth filtration media are commonly used for pre-filtration prior to surface filtration with substrates such as membranes.
Glass Microfiber Characteristics at a Glance
- Fastest flow rate
- High load capacity
- Retention of particles to sub-micron size
- Temperature range up to 500°C
- Use in liquid and gaseous filtration
- Inert fiber composition
- Free of binders or additives
Grade A
Fine porosity, fast flow rate, with a 1.6µm size particle retention. Frequently used in the filtration of precipitated proteins and cells. Ideally suited for use as a filter for radioimmuno assay of weak beta emitters by scintillation counting and gravimetric determination of airborne particulate. Binderless borosilicate glass microfiber.
Grade C
Fine porosity, fast flow rate, with a 1.2µm size particle retention. Primarily used for RIA procedures and harvesting lymphocytes. Binderless borosilicate glass microfiber.
Grade F
Fine porosity, medium flow rate, with a 0.7µm size particle retention. Frequently used with Grade D to filter diluted aqueous solutions containing strong oxidizing, acidic, or alkaline components prior to laser spectroscopy. May also be used for TCLP analysis and collecting extremely fine precipitated proteins, including immunoglobulins. Binderless borosilicate glass microfiber.
| Grade Nomenclature | Particle Retention | Thickness (mm) | Filtration Speed (sec.) | Basis Weight (g/m2 |
| A | 1.60 | 0.30 | 12 | 55 |
| C | 1.20 | 0.28 | 25 | 50 |
| F | 0.70 | 0.40 | 80 | 80 |