Stopcock

Laboratory Stopcocks for Controlled Flow Management

Stopcocks deliver precise flow control when you're running titrations, distillations, or vacuum work. Ground glass construction provides leak-proof sealing that won't quit halfway through a synthesis. You need reliability when handling corrosive reagents or working under vacuum.

Borosilicate 3.3 glass handles thermal shock from -196°C to +500°C.Standard taper joints (10/19, 14/23, 19/26, 24/29) connect directly to your existing glassware setup. Bore diameters range from 2mm to 8mm depending on flow requirements.

Precision Valve Solutions for Accurate Liquid and Gas Regulation

Ground glass plugs rotate smoothly inside precision-matched barrels. Minimal dead volume matters when you're working with expensive reagents or need quantitative transfers. Straight-bore models give maximum flow rates. Oblique-bore configurations provide better visual monitoring during transfers.

PTFE plug versions outperform glass when dealing with strong bases or hydrofluoric acid. They also eliminate the need for constant lubrication. Pair stopcocks with Nozzles and adapters for custom flow configurations. Works seamlessly with Bulb Allihn condenser setups and Coiled condenser assemblies in reflux operations.

Bore Size Selection and Flow Rate Control

• 2-3mm bore: Micro-scale work, dropwise additions, titration endpoints
• 4-6mm bore: Standard analytical procedures, moderate flow rates
• 7-8mm bore: Preparative chemistry, vacuum filtration, rapid transfers

Match bore diameter to viscosity. Thick solvents need wider openings. Taps offer alternative flow control but lack the precision of ground glass stopcocks for analytical work.

PTFE Plug Construction and Chemical Resistance

PTFE plugs handle concentrated acids, bases, and aggressive solvents that etch glass. No grease required means zero contamination risk. Temperature range drops to -200°C to +250°C with PTFE.

Glass plugs still win for high-temperature distillations above 250°C. They're also better for vacuum applications requiring absolute leak-proof seals. Check compatibility with Different glass products in your setup, especially when connecting to Bulb Allihn condenser and GL14 joints.

Proper Maintenance for Long-Term Reliability

• Clean plugs immediately after use with appropriate solvents
• Apply thin film of stopcock grease to glass plugs (not PTFE)
• Store with plugs slightly loosened to prevent freezing
• Inspect ground surfaces for scratches or etching quarterly
• Replace if you feel grinding or see leaks under vacuum

Dried reagents lock plugs solid. Soak in warm solvent bath before forcing rotation. Never overtighten - finger pressure is enough for proper sealing.