Filter funnel with glass disc

Filter Funnel with Glass Disc - Laboratory Filtration Equipment

Sintered glass filter funnels eliminate the need for disposable filter papers through an integrated porous disc that provides consistent, reproducible particle retention. Borosilicate glass construction withstands thermal shock and aggressive solvents encountered in analytical chemistry workflows. Standard taper ground glass joints (14/23, 19/26, 24/29) enable direct connection to receiving vessels including Buchner Flask with socket configurations for vacuum-assisted separations.

Glass Disc Filtration Technology for Precise Laboratory Separation

Fritted glass discs consist of sintered borosilicate particles fused at controlled temperatures to create uniform pore structures. Disc diameter ranges from 25mm to 90mm accommodate sample volumes from analytical-scale (5-10mL) to preparative quantities (500mL+). Maximum operating temperature reaches 500°C, though vacuum applications typically remain below 200°C to prevent thermal stress on joint connections.

Sintered Glass Disc Construction and Porosity Options

• P5 (Extra Fine): 1.0-1.6μm pore diameter, retains fine precipitates like barium sulfate
• P4 (Very Fine): 4-5.5μm retention, suitable for crystalline solids
• P3 (Fine): 16-40μm openings for general precipitate filtration
• P2 (Medium): 40-100μm pores for coarse particle separation
• P1 (Coarse): 100-160μm retention, rapid drainage applications

Porosity selection depends on particle size distribution and required flow rates. P4 and P5 grades demand stronger vacuum sources due to increased flow resistance, often requiring dedicated vacuum pumps rather than aspirator systems.

Applications in Vacuum Filtration Systems

Gravimetric analysis workflows benefit from tared funnel weights that remain constant across multiple determinations. Connect directly to Round Bottom Flask with two necks or Round Bottom Flask with three necks when simultaneous vacuum application and solvent addition are required. Flask pear shape receivers accommodate crystallization procedures where filtered solutions undergo controlled cooling. Pharmaceutical precipitate isolation, environmental sample clarification, and organic synthesis workups represent primary use cases. Glass disc funnels outperform paper filters when handling strong acids, bases, or oxidizing agents that degrade cellulose.

Cleaning and Maintenance Guidelines

• Reverse-flow cleaning: Apply vacuum to stem while submerging disc in solvent
• Chromic acid soaking removes organic residues (handle with appropriate PPE)
• Ultrasonic bath treatment at 40kHz dislodges embedded particles
• Calcination at 500°C burns off carbonaceous deposits (P1-P3 grades only)
• Store inverted to prevent dust accumulation on disc surface

Avoid alkaline solutions above pH 10 which etch borosilicate glass and enlarge pore structures. Inspect discs under transmitted light to verify uniform translucency indicating unobstructed flow paths.