Grade 169, Circle, 4.25cm

Ahlstrom binder-free glass filter papers are ideal for use in water and wastewater analysis, gravimetric analysis involving ignition of the sample and filtration of hot gases and liquids. They are recommended for use in environmental applications, biochemical testing, as pre-filters and as direct sample application pads. Binder-free glass microfibers feature maximum flow efficiency, fine particle retention, while maintaining a higher loading capacity than cellulose filters. Glass microfibers are chemical and thermal resistant and maintain their operational integrity in the presence of acids, alkalis, organic solvents, and temperatures at or above 500°C. Grade 169: 1.0 μm Thermally stable to over 550°C Total suspended solids determination Volatile solids testing EPA and ASTM protocols Total dissolved solids Characteristics and Benefits Consistent uniformity and longer shelf life make it possible for custom cut sizes and bulk packaging. Ahlstrom offers eight grades containing no binders or other additives that may cause interference in sensitive enzymatic or other chemical reactions. Environmental Laboratory Applications: STM 2540 Total, Dissolved, Suspended, Fixed and Volatile Solids (Mining Laboratory Applications also) Test method for the measurement of matter suspended or dissolved in water or wastewater. These solids analyses are important for the control of biological and physical wastewater treatment processes and for assessing compliance with regulatory agency effluent requirements. Grade 161 is our traditional recommendation and continues to be effective. Grade 169 is a newer grade designed specifically for gravimetric analysis. It has an improved ability to maintain the same weight before and after the drying procedure and is Ahlstrom’s current preferred recommendation for this test. STM 2710.B,D,E Tests on Sludges: Oxygen-Consumption Rate, Sludge Volume Index, Zone Settling Rate (Mining Laboratory Applications also) Each of these tests requires the suspended solids concentration to calculate the property of interest. This value is determined via STM 2540. STM 7500-Ra Radium Detection: Precipitation Method The precipitate is collected on a glass fiber filter, such as Grade 169, to measure its weight and radioactivity. STM 7500-Sr Strontium Detection: Precipitation Method The precipitate is collected on a paper filter, such as Grade 94, or a glass fiber filter, such as Grade 169, to measure its weight and radioactivity.