Dropping Funnels vs Pressure Equalising Funnels: When to Use Each

In organic chemistry and distillation, controlled reagent addition is critical for safety and accuracy. Two types of glass funnels — dropping funnels and pressure equalising funnels — are widely used, yet their functions differ in important ways. Choosing the right one helps Australian laboratories maintain precision, minimise risks, and comply with ISO and ASTM standards.

Why Controlled Addition Matters

Uncontrolled reagent addition can cause splashing, temperature spikes, or incomplete reactions. Funnels provide a safe way to introduce liquids gradually while preventing contamination. LabChoice Australia manufactures both dropping funnels and pressure equalising funnels from BORO 3.3 borosilicate glass, ensuring chemical durability and resistance to repeated heating and cooling cycles.

Dropping Funnel vs Pressure Equalising Funnel

When to Use Each Funnel

• Dropping Funnels: Suitable for schools and teaching labs. A Melbourne university equips students with 100 mL dropping funnels to introduce acids dropwise into Erlenmeyer flasks, ensuring safety during titration-style experiments.
• Pressure Equalising Funnels: Essential for sealed systems. A Sydney pharmaceutical lab uses LabChoice BORO 3.3 pressure equalising funnels in reflux and distillation setups to avoid dangerous pressure build-up and ensure precise solvent addition.

LabChoice BORO 3.3 Advantage

All LabChoice funnels are made from BORO 3.3 borosilicate glass in compliance with ISO 1773 standards, guaranteeing superior chemical resistance, thermal stability, and safe performance under vacuum or heating. With precision-ground joints and PTFE stopcocks available, LabChoice ensures Australian labs receive durable, high-quality equipment for both teaching and advanced research.

FAQs

Why use a pressure equalising funnel instead of a dropping funnel?
It prevents pressure differences when adding liquids to a closed system such as a reflux setup.

Can both funnels be autoclaved?
Yes, BORO 3.3 glass funnels withstand repeated autoclaving cycles.

Do LabChoice funnels come with PTFE stopcocks?
Yes, both dropping and pressure equalising funnels are available with PTFE or glass stopcocks.

Which funnel is better for schools?
Dropping funnels are simpler, safer, and more cost-effective for classroom experiments.

📚 References

Standards & Specifications

1. ISO 1773:1997 – Laboratory glassware — Conical flasks (applicable reference for glass funnel joint standards). International Organization for Standardization.
   https://www.iso.org/standard/30950.html
2. ISO 4797:2015 – Laboratory glassware — Boiling flasks with conical ground joints (joint and pressure compatibility standards). International Organization for Standardization.
   https://www.iso.org/standard/64894.html
3. ASTM E1406-98(2015) – Standard Specification for Laboratory Glassware Jointed Funnels. ASTM International.
   https://www.astm.org/e1406-98r15.html

Academic & Safety Guides

CSIRO – Laboratory Safety Guidance – Safe Handling of Glass Funnels and Pressure Systems in Australian Laboratories. CSIRO, Australia.
https://www.csiro.au

American Chemical Society (ACS) – Guidelines for Safe Use of Funnels in Organic Chemistry Labs. ACS Education and Safety Resources.
https://www.acs.org/safety

University of Sydney – School of Chemistry – Organic Chemistry Laboratory Manual: Use of Dropping and Pressure Equalising Funnels in Reflux and Distillation. Sydney, Australia.