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    Glass Fibre Filters

    Glass Fibre Filters Johnson Test Papers offers a full range of binder free glass fibre filters made with 100% borosilicate glass microfibres. They are chemically resistant towards most organic and inorganic solvents (except HF) as well as acids and alkaline solutions of high concentration. They resist temperatures up to 500°C. Due to their very fine fibres and combined with good permeability they are particularly suitable for micro-filtration. They are non-hygroscopic and biologically inert. They can be used in various fields, especially when fine fast filtration and high loading capacity is required. Applications for Johnson Test Papers' glass fibres include environmental analysis for water, wastewater, testing of soils, air pollution and monitoring, research and process biochemistry, and gravimetric analysis involving ignition of samples. Johnson Test Papers' glass fibre filters are also found in the filtration of hot gases and liquids, and in pre-filtration.

    The following list contains recommendations as to the application of these glass fibre filters. Quite often it is necessary to find an individual solution. It is our pleasure to give you advice for your filtration problems.

    Water Pollution Control

    Water needs our special protection and there are many ways of assessing it's quality. Water can be contaminated physically, chemically and biologically. Physical contamination refers to solid, filterable material present in the water sample. Chemical contamination includes dissolved heavy metals, nitrogen compounds and organic carbon. Biological contamination can be caused by bacteria and microorganisms present in the water sample.

    Common water monitoring procedures include the determination of Total Suspended Solids using glass fibre filters, analysis of heavy metal and ion content using syringe filters for sample preparation as well as microbiological analysis using sterile, gridded membrane filters. Our product range includes high performing filters for all of the above analysis procedures.


    Click on a Grade to find out more...

    Grade 50934AH

    - Fast

    Grade 50A

    - Fast, high loading

    Grade 50B

    - Medium / Fast, very high loading

    Grade 50C

    - Medium / Fast, very high loading

    Grade 50D

    - Slow, very high loading

    Environmental Monitoring

    Contaminated air or exhaust air escaping a factory, plant or a vehicle is classified by the term emission. Emission volume needs to be reduced in order to minimize the danger for the environment. Individual controls and continuous measurements are indispensable. Filter media made of glass fibres have proven appropriate in all the various existing applications.

    • Chemical Stability - Resistant to the majority of reagents and solvents, except acidic and base solutions of high concentration.
    • Thermal Stability - Can withstand operating temperatures of up to 500C. In case of operating temperatures of up to 900°C we recommend the use of Johnson Test Papers quartz microfibre filters.
    • Mechanical Resistance - Resistant to creasing, therefore can be folded and transported to the laboratory for field atmospheric analysis.
    • Permeability - High permeability of air therefore good flow velocities. Makes them ideal for the use in high-volume detectors.
    • Retention of particles - Excellent level of retention due to physical and chemical qualities not only on the surface but also at depth through mechanisms of electrostatic adsorption and other processes, resulting in some cases to sizes of retention smaller than a micron.
    • Stability in weight - Since they are not hygroscopic, the glass microfiber filters do not exhibit significant variations in weight.
    • Load Capacity - Due to its high apparent density (relationship between weight in grams and thickness) and the nature of the fibers, these filters have a high load capacity.

    Available Grades
    Grade Whatman Equivalent Speed Thickness (mm) Pore Size (μM) Weight (g/m²) Filtration Speed (sec*) Burst Strength (Kg/cm)²
    50934AH 934AH Fast 0.28 1.5 65 60 20
    50A = No.GFA Fast, high loading 0.26 1.6 52 60 20
    50B = No.GFB Medium / Fast, very high loading 0.70 1.0 143 200 50
    50C = No.GFC Medium / Fast, very high loading 0.26 1.2 52 100 20
    50D = No.GFD Slow, very high loading 0.53 2.7 120 30 20