KSE offers a wide variety of membrane filter support glassware for most vacuum filtration assemblies. To select the right support glassware for your need, choose 25, 47, or 90 mm, according to the diameter of your filter membrane; then, select either a fritted glass or stainless steel support. Finally, choose the appropriate connection for the flask or bottle you will use to collect the filtrate. Following is the basic information you will need to select the most appropriate glassware for your application. Filter Size: 25 mm Support Glassware is designed when filtering small volumes of liquids in particulate or biological contamination studies. We recommend 47 mm Support Glassware when analyzing up to 500 mL of liquids for particulate or biological contamination, water/wastewater analysis (Reference: Standard Methods for the Examination of Water and Wastewater, 19th Edition, 1995), sterility testing of pharmaceuticals by the bacteria retentive filter method (Reference: U.S. Pharmacopeia XXIII), and for particulate-free or sterile filtrate preparation. We recommend 90 mm Support Glassware when filtering large sample volumes, liquids with a heavy particulate load and viscous liquids when a high flow rate is required. The larger filter area can provide filtration rates four times faster than 47 mm assemblies. Support Style: We recommend fritted glass supports for general membrane filtration analysis of samples for microbiological or particulate contamination. This support style is appropriate when using gridded filters because the glass frit provides the most even distribution of the sample through the filter membrane. All of the fritted glass support bases have a coarse (40-60 ¦m) porosity. We recommend stainless steel supports when filtering viscous or proteinaceous solutions to give the maximum flow rate. This support style is also ideal for producing ultra-clean filtrate, since the stainless steel screen will not shed particles into the filtrate. Connection to Flask/Bottle: Silicone or neoprene stoppers are the most common connectors used to connect the filtration assembly to an Erlenmeyer style flask, and are appropriate for most routine filtration studies of aqueous solutions. However, we do not recommend stoppers when filtering organic or most corrosive solutions or when preparing HPLC mobile phase. We recommend filtration assemblies with standard taper 40/35 outer joint connections when filtering corrosive solutions and organic solvents. This connection style is also ideal when preparing HPLC mobile phase, since the (all-glass÷ connection eliminates phthalate contamination that can occur when using silicone or neoprene stoppers. The 25 mm vacuum filtration assemblies are designed to handle small volumes of liquids for analysis of particulate or microbiological contamination. The glass components are manufactured from Wheaton 33« low extractable borosilicate glass (meets ASTM Type I Class A and USP Type I standards).