Funnel Separatory pear shape

Pear-Shaped Separatory Funnels for Liquid-Liquid Extraction

Borosilicate glass construction with precision-ground stopcocks defines these extraction workhorses. The pear geometry concentrates the lower phase into a narrow stem, reducing dead volume during drainage and improving phase boundary visualization. Standard taper joints (24/40 most common) mate directly with Buchner Flask receivers or collection vessels equipped with Hollowed glass stoppers for sealed storage.

Pear-Shaped Design Advantages in Liquid Separation

Sloped sidewalls channel emulsions and suspended particulates toward the central axis during settling. The tapered lower section concentrates the denser phase into a 15-20mm diameter stem, allowing operators to drain aqueous layers while retaining organic phases with minimal interface loss. Contrast this with cylindrical Separatory Funnel designs where larger stem diameters (25-30mm) increase the risk of co-draining both phases during transfer.

Enhanced Drainage Characteristics of Pear Geometry

• Reduced holdup volume: Conical transition from body to stem minimizes trapped liquid in corners—typically 0.5-1.5mL residual vs. 3-5mL in cylindrical models
• Laminar flow patterns: Smooth curvature eliminates turbulence during drainage, preventing phase re-mixing at flow rates up to 15mL/sec
• Stopcock positioning: Either PTFE screw stopcock or glass plug variants mount 8-12cm below the widest diameter, ensuring complete lower phase evacuation

Optimal Interface Visibility During Extraction

The bulbous upper section provides 120-180° viewing angles of the phase boundary. Graduated markings (±5% accuracy) appear on the straight neck section where meniscus reading is most precise. When working with dichloromethane/water or ethyl acetate/brine systems, the pear profile positions interfaces 40-60mm above the stopcock bore—far enough to prevent accidental drainage yet close enough for accurate volume measurement. Related Funnels for filtration lack this phase separation capability entirely.

Standard Taper Fittings for Laboratory Integration

• ISO 4800 compliance:Funnel Separatory pear shape ISO4800 models feature 19/26, 24/29, or 29/32 ground joints for universal compatibility
• Temperature tolerance: Type I borosilicate withstands thermal shock from -80°C cryogenic washes to +180°C reflux conditions
• Capacity range: 50mL units for microscale work (0.1-5g substrate) up to 2L vessels for pilot-scale extractions