Specifications

Component List

All components listed below are included in this kit. Items marked Optional can be customized.

Available Joint Sizes · GB/ISO/ASTM Standards

All sizes share 1:10 standard taper — GB, ISO, and ASTM sizes are interchangeable

14/19 19/26 24/29 (GB·recommended) 29/32 34/35 · 45/40 · 50/42 custom

GB (Chinese) 14/19 · 19/26 · 24/29 · 29/32 ISO 14/19 · 19/26 · 24/29 · 29/32 ASTM (American) 14/20 · 19/22 · 24/40 · 29/42

* All components have matching joint sizes for full system compatibility. ASTM and GB/ISO sizes share 1:10 taper — seal lengths differ but are interchangeable.

Component	Standard Spec	Available Joint Sizes	Upgrade Options	Qty	Link
Please contact us to confirm the available specifications.

📌 Customization Notes:
• Joint size can be selected to match your existing lab system:
GB (Chinese): 14/19 · 19/26 · 24/29 · 29/32
ISO: 14/19 · 19/26 · 24/29 · 29/32
ASTM (American): 14/20 · 19/22 · 24/40 · 29/42
• Flask can be upgraded to three-neck for simultaneous addition, stirring, and inert gas introduction
• Condenser options: spherical (standard), serpentine (low-boiling), straight (distillation)
• All optional specifications can be freely combined with no minimum order quantity
• For special requirements, please contact our technical team

💡 Recommended Add-Ons: Magnetic stirrer + stir bar · Thermometer (0–200℃) · Anti-bumping granules · Silicone tubing (Φ8mm × 2m) · Condenser cooling water connectors

Product Description

I. Principle of Reflux

Reflux is an operation that maintains a reaction at its boiling temperature without loss of reactants or solvent. The principle is simple: the reaction flask is heated to boiling, vapor rises into the condenser, condenses upon cooling, and returns to the reaction flask — cycling continuously.

Unlike distillation, the purpose of reflux is to maintain reaction temperature and continuous stirring, not to separate components. Reflux allows the reaction to proceed at the solvent's boiling point while ensuring the system volume does not decrease due to evaporation. The vast majority of organic synthesis reactions are conducted under reflux.

✦ Reflux vs Distillation: Reflux: vapor condenses and returns to the reaction flask — maintains temperature, retains solvent.
Distillation: vapor condenses and is collected in a receiver — separates and collects fractions.
The key difference is whether the condensate returns to the reaction system.

II. Apparatus Components & Functions

Round-Bottom Flask — Contains reactants and solvent; single-neck or three-neck
Spherical Condenser — Standard for reflux; large cooling surface, vapor condenses in the bulbs and returns directly
Heating Mantle (or Oil/Water Bath) — Provides uniform, controllable heat
Iron Stand & Universal Clamps — Secure the flask and condenser; ensure vertical stability
Magnetic Stirrer (optional) — Provides stirring for uniform heat distribution

III. Condenser Type Comparison

Spherical Condenser: The preferred choice for reflux — the spherical bulbs increase cooling surface, providing efficient condensation for most reflux reactions
Serpentine Condenser: Coiled inner tube provides a longer cooling path — ideal for low-boiling solvents (boiling point below 80℃)
Straight Condenser: Typically used for distillation — not recommended for reflux

IV. Material & Workmanship

All glass components are manufactured from borosilicate glass 3.3. All ground joints are precision-machined to the standard 1:10 taper, available in GB, ISO, and ASTM standard sizes.

This apparatus is designed and manufactured in compliance with GB/T 21298-2017 "Laboratory Glassware — Distillation Apparatus".

Applications

Typical Applications

Organic Synthesis

Esterification, hydrolysis, nucleophilic substitution, addition reactions — the vast majority of organic synthesis

Reflux Extraction

Extracting soluble components from natural products or solid samples

Polymerization

Maintaining reaction temperature in polymer synthesis

Teaching Labs

Core hands-on operation in undergraduate organic chemistry courses

Solid-Phase Reactions

Reactions between solids and liquids under reflux conditions

Solvent	Boiling Point (℃)	Recommended Condenser
Please contact us to confirm the available specifications.

Operation & Maintenance

User Guide

The following is the standard operating procedure for the reflux apparatus. Reflux is one of the most fundamental lab operations — but details determine success.

I. Safety Check & Preparation

Inspect all glass components for cracks or chips
Work in a fume hood — wear lab coat, safety goggles, and gloves
Confirm the heating device (heating mantle or oil bath) is functioning properly
Prepare cooling water source with adequate flow
Check system venting — the reflux setup is typically an open system (the condenser top is vented to atmosphere)

Standard assembly sequence (bottom to top)

Secure the round-bottom flask on the iron stand at the correct height, positioned in the heating mantle
Add reactants and solvent — fill to 1/3 to 1/2 of flask capacity
Add 2–3 boiling stones or anti-bumping granules, or insert a magnetic stir bar
Attach the connector (or directly attach the condenser) to the flask
Install the spherical condenser — ensure the ground joint is properly seated
Secure the flask neck and condenser mid-section with universal clamps — ensure the apparatus is vertical
The condenser top must remain open — vented to atmosphere (never seal!)

III. Cooling Water

Turn on cooling water BEFORE heating
Follow the bottom-in, top-out principle
Water flow should be slow and steady — excessive flow reduces heat exchange efficiency

IV. Heating & Reflux

Heat slowly with the heating mantle — NEVER use an open flame with flammable solvents
Observe the liquid begin to boil and vapor rise into the condenser
Key indicator: Vapor should condense in the middle 1/3 to 1/2 of the condenser. If vapor reaches the top, increase cooling water flow or reduce heating
Adjust heating to maintain a steady reflux rate — 2–3 drops/second of condensate returning
Once reflux is established, the reaction proceeds at the solvent boiling point — monitor color and physical state changes

V. Shutdown

After the reaction is complete, turn off the heating device first
Keep cooling water circulating until the apparatus cools to near room temperature
When no more condensate is returned, turn off the cooling water
Disassemble in reverse order
Clean all glassware, dry, and store properly

📌 The condenser top must remain open! In a reflux setup, the condenser top must be vented to atmosphere (a cotton plug may be used to keep out dust). Never seal the top — sealed systems build up internal pressure during heating and risk glass rupture.

💡 From a Seasoned Lab Technician: "No vapor escapes, no condensation floods." — A well-running reflux shows vapor condensing steadily in the middle of the condenser, neither escaping from the top nor pooling liquid at the bottom.
If condensate flows in a stream rather than dripping, the cooling water flow is too high — reduce it slightly for better heat exchange.
Reflux time is counted from when steady reflux is established, not from when heating begins.
If bumping occurs in the flask, reduce heating immediately; if stirring is causing it, reduce stirrer speed.

Care & Notes

Show care & notes

⚠️ Safety & Compliance Checklist

Fire/explosion prevention

When refluxing flammable solvents (e.g., ether, acetone), NO open flame — always use a heating mantle

Ventilation

All reflux operations must be performed in a fume hood

Standard compliance

Apparatus design complies with GB/T 21298-2017

Do not

Condenser top must be vented: Never seal a reflux system — pressure buildup risks glass rupture
Anti-bumping: NEVER add boiling stones to a hot flask! Always cool first, then add

Reflux Apparatus

Specifications

Component List

Product Description

I. Principle of Reflux

II. Apparatus Components & Functions

III. Condenser Type Comparison

IV. Material & Workmanship

Applications

Organic Synthesis

Reflux Extraction

Polymerization

Teaching Labs

Solid-Phase Reactions

User Guide

I. Safety Check & Preparation

Standard assembly sequence (bottom to top)

III. Cooling Water

IV. Heating & Reflux

V. Shutdown

Care & Notes

Fire/explosion prevention

Ventilation

Standard compliance

Need This Apparatus Kit?

Reflux Apparatus

Specifications

Component List

Product Description

I. Principle of Reflux

II. Apparatus Components & Functions

III. Condenser Type Comparison

IV. Material & Workmanship

Applications

Organic Synthesis

Reflux Extraction

Polymerization

Teaching Labs

Solid-Phase Reactions

User Guide

I. Safety Check & Preparation

Standard assembly sequence (bottom to top)

III. Cooling Water

IV. Heating & Reflux

V. Shutdown

Care & Notes

Fire/explosion prevention

Ventilation

Standard compliance

Related Apparatus Kits

Reflux with Dropping Addition

Simple Distillation

Heated Stirring Synthesis

Soxhlet Extraction

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