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What is Grade 50A?

Johnson Test Papers’ Grade 50A glass microfiber filters offers fine particle retention with high filtration speed and good loading capacity. 50A filters are suitable for water quality parameter measurement and air filtration applications.

  • Suitable for a wide range of liquid and air filtration applications
  • Nominal pore size of 1.6 µm
Johnson Test Papers offers a variety of binder-free glass microfiber filters for different sample types and analysis needs. For higher wet strength, increased loading capacity, or different particle retention, see Johnson Test Papers’ other binder-free filter options.
Johnson Test Papers glass microfiber filters without binder

Filters that combine high loading capacity with fine particle retention are highly efficient for applications such as general laboratory filtration, clarification of buffer and reagent solutions, wastewater and water in general. Grade 50A meets these requirement as well as being useful for water quality parameter measurements involving large sample volumes. Grade 50A filters can function as wastewater filters or serve as filters in the following applications:

  • Water pollution monitoring of effluents
  • Foodstuff analysis
  • Radioimmunoassay of weak β emitters
  • Gravimetric determination of airborne particulates
  • Atmospheric and water pollution monitoring such as intake controls, ozone-level, and water effluents.
  • Filtration of water and protein
  • Testing of algae, bacteria cultures
  • Filtering solvents in a high-resolution laboratory.
  • Scintillation counting on the filter
  • Cell harvesting
  • Hydrocarbon analysis where cellulose fibers are an inconvenience

Grade 50A corresponds to many international standards for air and water pollution monitoring

Whatman Cross Reference = No.GFA
Speed class Fast, high loading
Thickness (mm) 0.26
Pore size (μM) 1.6
Weight (g/m²) 52
Filtration Speed (sec*) 60
Burst Strength (Kg/cm²) 20
*According to DIN 53137
Available Sizes
Diameter (mm) Product Code
21 50A021
24 50A024
25 50A025
47 50A047
55 50A055
90 50A090
110 50A110
125 50A125