Specifications

Constant-Pressure Funnel · Specifications

The following are general specifications. Multiple configurations can be combined. For custom sizes or special structures, please contact our sales team.

Request custom specs

1. Capacity & Joint Sizes

Capacity (ml)	Common Joint Sizes	Stopcock Bore (mm)	Stopcock Type	Material
Please contact us to confirm the available specifications.

* 5000ml capacity commonly uses 40# standard joint; some manufacturers use 45/50.
* Both DIN (EU) and ASTM standards use 1:10 taper and are mutually compatible.
* Glass stopcock taper is 1:10; PTFE stopcock taper is 1:5.

2. Stopcock Type Comparison

Stopcock Type	Taper	Material	Temperature	Features	Applications
Please contact us to confirm the available specifications.

* Needle PTFE stopcock provides fine control down to 0.1ml/min with dual PTFE seals.
* Double stopcock models offer more flexible flow control.
* Custom stopcock types and special structures available upon request.

Product Description

The constant-pressure funnel is a specialized device for precise liquid addition in standard joint glassware, widely used in organic synthesis, titration, and pharmaceutical R&D. Its unique pressure-equalizing design through a side arm maintains consistent internal pressure with the atmosphere, ensuring smooth and stable liquid delivery regardless of system pressure changes. Compared to standard separatory funnels, the constant-pressure funnel prevents back-suction, ensures smooth liquid flow, and minimizes the impact of added liquid on gas pressure.

Key Features

Borosilicate Glass 3.3: ISO 3585 compliant, low expansion, thermal shock 280°C
Pressure-Equalizing Design: Side arm balances internal and external pressure for stable addition
Dual Graduation Marks: Doublegraduation lines for precise volume measurement
Standard Joint: 1:10 taper, precision ground for reliable sealing
Two Stopcock Options: Glass (1:10 taper) and PTFE (1:5 taper) for different applications
Multiple Sizes: DIN (EU) 14/23 ~ 60/45 and ASTM equivalents
Multiple Capacities: 10ml ~ 5000ml full range, 5000ml with 40# standard joint
High Transparency: Easy observation of liquid level and addition rate
Chemical Resistant: Suitable for various organic solvents

Quality Assurance

Every constant-pressure funnel undergoes strict dimensional inspection, joint taper testing, and thermal resistance testing to ensure compliance with applicable standards.

Note: Ensure joints are clean and dry before use to prevent sticking. Check stopcock sealing before operation. PTFE stopcocks may be lubricated with PTFE grease. Use accessories of the same joint size for optimal sealing. Large capacity models (2000ml, 5000ml) should be secured with a support stand.

Applications

Typical Applications

Organic Synthesis

Grignard reactions, addition reactions, condensation reactions

Pharmaceutical R&D

Controlled addition of critical reagents in API synthesis

Titration Analysis

Acid-base titrations, redox titrations

Extraction & Separation

Solvent addition and liquid separation

Education

University organic chemistry lab teaching

Pilot Production

2000ml, 5000ml capacities for pilot-scale reactions

Typical Apparatus Assembly

Upper joint → Addition port / Sealing stopper

Lower joint → Reaction flask / Three-neck flask

Side pressure-equalizing arm → Balances system pressure

Stopcock → Precise control of addition rate

Tip: The constant-pressure funnel is key equipment for precise reaction rate control. The pressure-equalizing design ensures stable addition even when system pressure changes. Use accessories of the same joint size for optimal sealing.

Constant-Pressure Funnel · Selection Guide

Select the right configuration based on your experimental needs:

📌 General Organic Synthesis

For most organic synthesis reagent addition with moderate corrosion resistance requirements.

Recommended: Glass Stopcock · 24/40 · 250ml / 500ml

🧪 Strong Acid/Base Systems

For strong acids, bases, or corrosive reagent addition.

Recommended: PTFE Stopcock · 24/40 · 250ml / 500ml

🎯 Micro Precision Addition

For ultra-low flow rate, high-precision addition requirements.

Recommended: Needle PTFE Stopcock · 14/20 · 60ml / 125ml

🔬 High Purity / No Contamination

For systems sensitive to metal ions or grease contamination.

Recommended: PTFE Stopcock (no grease required) · Glass or PTFE

🏭 Pilot / Large Scale

For large-scale reaction systems requiring large capacity addition.

Recommended: Glass or PTFE Stopcock · 40# · 2000ml / 5000ml

🔀 Complex Addition Schemes

For simultaneous control of multiple channels or switching addition paths.

Recommended: Double Stopcock · 24/40 · 250ml / 500ml

Selection Tip: Recommendations are for common scenarios. For actual selection, consider reagent properties, required addition rate, and reaction scale. Contact our technical team for assistance.

Operation & Maintenance

User Guide

Preparation

Inspect funnel for cracks, chips, or scratched joints
Clean all joint surfaces with a soft cloth or cotton swab
Check stopcock rotation; glass stopcock may need a small amount of vacuum grease
PTFE stopcock requires no grease; check O-ring integrity
Ensure pressure-equalizing arm is clear and unobstructed

Installation & Connection

Connect the lower joint to the reaction flask or three-neck flask
Upper joint can connect to an addition port or sealing stopper
Insert with gentle twisting motion, do not force
Secure the funnel with a clamp for stability
Confirm stopcock is closed before adding liquid

Addition Operation

Add liquid through the upper opening
Slowly open the stopcock and observe drop rate
Adjust stopcock opening to control addition rate
Needle PTFE stopcock allows fine adjustment via tail knob
Pressure-equalizing arm ensures smooth liquid flow
Monitor dual graduation marks for precise total volume

Disassembly & Cleaning

Close stopcock first, allow system to cool
Gently twist to detach the funnel
Clean immediately after use to prevent residue buildup
Wash joints with soft brush and detergent, avoid hard objects
Glass stopcock can be cleaned with organic solvents
PTFE stopcock can be cleaned with organic solvents; maintain O-ring
Air dry after washing, store with soft paper between joints

Care & Notes

Show care & notes

Safety Tips

Control addition rate when adding flammable reagents to prevent localized overheating
PTFE stopcock maximum operating temperature: 250°C
Large capacity models (2000ml, 5000ml) must be secured with a support stand
Always work in a fume hood when handling hazardous chemicals

Do not

Do not use cracked or chipped funnels for experiments