Specifications

Component List

The kit contains the components listed below. Items marked Optional can be selected according to your requirements.

Compatible joint sizes · GB / ISO / ASTM

All sizes use the 1:10 standard taper, so GB, ISO and ASTM joints can be used together

14/19 19/26 24/29 (GB · Recommended) 29/32 34/35 · 45/40 · 50/42 on request

GB (GB/T) 14/19 · 19/26 · 24/29 · 29/32 ISO (EU) 14/19 · 19/26 · 24/29 · 29/32 ASTM (US) 14/20 · 19/22 · 24/40 · 29/42

* All components share the same joint size for full compatibility. ASTM and GB/ISO both use a 1:10 taper; the ground length differs, but the joints are interchangeable.

Component	Recommended	Compatible Joints	Optional Upgrade	Qty	Link
Please contact us to confirm the available specifications.

📌 Customisation notes:
• Joint sizes can be chosen freely to match your existing laboratory system:
  GB (GB/T): 14/19 · 19/26 · 24/29 · 29/32
  ISO (EU): 14/19 · 19/26 · 24/29 · 29/32
  ASTM (US): 14/20 · 19/22 · 24/40 · 29/42
• Vacuum pump options: diaphragm pump (1–10 mbar, general solvents) / rotary vane pump (10⁻³ mbar, deep vacuum) / dry screw pump (corrosion-resistant, high vacuum)
• All optional specifications can be combined freely, with no minimum order quantity
• For special specifications, contact our technical team to discuss a custom build

💡 Recommended to order together: Vacuum pump (diaphragm / rotary vane) · vacuum grease · magnetic stirrer + stirrer bar · thermometer (0–200°C / 0–300°C) · heating mantle (matched to flask volume) · Dewar flask (for the cold trap) · dry ice or liquid nitrogen (as required)

Product Description

1. Principle of Vacuum Distillation

The boiling point of a liquid is the temperature at which its vapour pressure equals the surrounding atmospheric pressure. When system pressure is reduced, the boiling point falls as well. Vacuum distillation applies this principle: a vacuum pump lowers the pressure inside the distillation system so that high-boiling compounds vaporise well below their atmospheric boiling point, avoiding thermal decomposition.

By operating pressure, vacuum distillation is divided into reduced-pressure distillation (above 1.33×10⁴ Pa), vacuum distillation (1.33×10⁴–266.6 Pa) and high-vacuum distillation (below 266.6 Pa). This kit covers the 1–10⁻³ mbar range, which meets the large majority of laboratory reduced-pressure distillation needs.

✦ Boiling point vs pressure: If a compound's boiling point is known at atmospheric pressure or at a given pressure, a nomograph can be used to estimate its boiling point at the target pressure. Estimates for polar compounds tend to run low — confirm by an actual trial distillation.

2. Kit Composition and Function

A vacuum distillation apparatus consists of four parts: the distillation section, the evacuation (reduced-pressure) section, the safety section and the pressure-measurement section.

Distillation flask (round-bottom) — holds the liquid to be distilled; thick-wall pressure-resistant glass is required
Claisen distillation head — standard component for vacuum distillation; prevents bumping liquid splashing into the condenser
Thermometer and adapter — monitors vapour temperature; the top of the mercury bulb should align with the lower edge of the head's side arm
Straight condenser — condenses vapour into liquid
Vacuum take-off (multi-tail receiver adapter) — allows receiving flasks to be switched without breaking vacuum
Cold trap — placed ahead of the vacuum pump to condense uncondensed vapour and protect the pump
Vacuum gauge — monitors system vacuum level
Buffer / safety flask — prevents suck-back
Vacuum pump — provides the vacuum source (diaphragm, rotary vane or dry screw)
Thick-wall vacuum tubing — connects components and resists collapse under negative pressure

3. Material and Workmanship

All glass parts of this kit are made from borosilicate glass 3.3, with wall thickness designed specifically to withstand vacuum. All joints are precision-ground to the universal 1:10 taper and are compatible with GB, ISO and ASTM joint systems. Every joint in vacuum distillation must be greased, otherwise the system cannot hold low pressure.

The kit is designed and manufactured in accordance with GB/T 21298-2017 Laboratory Glassware — Distillation Apparatus.

⚠️ Vacuum safety warning: Glassware used for vacuum distillation must be free of cracks, scratches and star-cracks, otherwise implosion under negative pressure can cause serious injury. Always work in a fume hood and wear safety goggles and a face shield.

Applications

Typical Applications

Natural product purification

separation and purification of heat-sensitive active compounds in plant extracts and essential oils

Pharmaceutical intermediates

purification of high-boiling intermediates while avoiding thermal decomposition

Fine chemicals

high-boiling solvent recovery and monomer purification

Petrochemical analysis

determination of reduced-pressure boiling ranges of petroleum fractions

Food and flavour

gentle separation of heat-sensitive aroma compounds and flavourings

Suitable Conditions

Liquid compounds with an atmospheric boiling point above 150°C
Compounds that decompose, oxidise or polymerise before reaching their boiling point at atmospheric pressure
Boiling point falling within 45–180°C at the chosen operating pressure
Not suitable for low-boiling compounds (atmospheric distillation is sufficient) or materials that are extremely pressure-sensitive

Pump Type	Ultimate Vacuum	Advantages	Best For
Please contact us to confirm the available specifications.

Operation & Maintenance

Operating Guide

The standard procedure for a vacuum distillation apparatus is below. The operating sequence for vacuum distillation differs completely from atmospheric distillation — please follow it strictly.

🚨 Critical sequence (do not reverse):
Start-up: cooling water on → stirrer on → vacuum pump on (gradual evacuation) → heat only after stabilisation
Shutdown: heating off → cool down → vent slowly (return to atmospheric) → vacuum pump off

Safety Check and Preparation

Glassware inspection (most important): check every glass item one by one and confirm there are no cracks, scratches or star-cracks. Any defect can cause implosion under negative pressure
Work in a fume hood, wearing a lab coat, safety goggles and a face shield
Confirm the vacuum pump is working properly (oil level, oil condition, pumping speed)
Prepare a cooling water supply (or a low-temperature circulator, coolant set to 0–10°C)
Confirm the heating device (mantle or oil bath) works properly; set the oil bath 20–30°C below the material's atmospheric boiling point

Standard assembly order (bottom-up, left-to-right)

Fix the round-bottom flask on the retort stand and set it at a suitable height
Carefully add the liquid through a funnel, filling the flask to between 1/3 and 1/2 of its capacity
Add the magnetic stirrer bar (boiling stones must NOT be used under vacuum)
Fit the Claisen distillation head onto the flask neck
Insert the thermometer into the adapter and align the top of the mercury bulb with the lower edge of the head's side arm
Connect the straight condenser; its upper end connects to the head's side arm
Connect the lower end of the condenser to the vacuum take-off (multi-tail type allows flask switching)
Vacuum port of the take-off → thick-wall vacuum tubing → cold trap → buffer flask → vacuum pump
Apply vacuum grease evenly to every joint to ensure the system seals
Secure the flask neck, condenser and take-off with universal clamps so the assembly is stable

Cooling Water and Stirring

Turn on the cooling water first; condenser flow is bottom-in, top-out
Start the magnetic stirrer at a steady speed, avoiding violent agitation of the liquid

Evacuation (critical step)

Keep the vent valve open and start the vacuum pump
Close the vent valve slowly, in stages, to evacuate gradually — never pull full vacuum in one step, or the liquid can bump and spray
Watch the vacuum gauge and record the pressure once the vacuum level stabilises
Check system tightness: switch off the pump and hold for 5 minutes; no significant rise in pressure means the seal is acceptable
Purpose of evacuation: evacuate before heating in order to remove low-boiling solvents and volatile impurities from the system

Heating and Distillation

Once the vacuum level is stable, raise the heating bath temperature slowly, in small increments
Control the distillation rate at 1–2 drops per second
Watch the thermometer closely — in vacuum distillation the reading can fluctuate as pressure varies
If the sample keeps refluxing without distilling, insulate the flask and head with glass wool or aluminium foil
Switching fractions: open the vent valve slightly to relieve pressure, rotate the multi-tail take-off to the next flask, then re-evacuate

Shutdown (key to preventing suck-back and breakage)

Switch off the heating and lower the bath or remove the mantle
Keep the cooling water circulating and the stirrer running while the apparatus cools down fully
Open the vent valve slowly to equalise pressure; only switch off the vacuum pump once the system is fully at atmospheric pressure
Never vent while the system is hot! It can cause bumping, spraying or glass breakage
Dismantle only after all glass parts have cooled to room temperature
Never distil to dryness! Keep a small amount of residue in the flask

📌 Special requirements for vacuum lines: Thick-wall vacuum tubing must be used — ordinary rubber tubing collapses under negative pressure. The cold trap should be placed ahead of the vacuum pump to condense uncondensed vapour and protect the pump. Dry ice–acetone or liquid nitrogen is recommended as the cooling medium in the trap.

💡 From experienced hands: Temperature fluctuation during vacuum distillation is normal — a small pressure change shifts the boiling point. What matters is watching the distillation rate and the position of the condensation ring: a steadily rising ring means distillation is proceeding normally. If the ring stops rising, raise the heating temperature slowly and in small steps — never make large adjustments. One more key point: when distilling compounds boiling above 200°C, keep the oil bath below 200°C to prevent it catching fire.

Care & Notes

Show care & notes

⚠️ Safety and compliance points

Implosion protection

use a blast shield or full face shield; always run vacuum distillation in a fume hood

Anti-suck-back

at shutdown, vent first and switch off the pump second — the order cannot be reversed

Flammable solvents

use an explosion-proof vacuum pump with low-flash-point solvents

Standard

the apparatus should be designed to comply with GB/T 21298-2017 Laboratory Glassware — Distillation Apparatus

Do not

Glassware: use thick-wall pressure-resistant glass only; never use items with cracks or scratches
Anti-bumping: boiling stones do not work under vacuum — a magnetic stirrer bar is required

Vacuum Distillation Apparatus

Specifications

Component List

Product Description

1. Principle of Vacuum Distillation

2. Kit Composition and Function

3. Material and Workmanship

Applications

Natural product purification

Pharmaceutical intermediates

Fine chemicals

Petrochemical analysis

Food and flavour

Operating Guide

Safety Check and Preparation

Standard assembly order (bottom-up, left-to-right)

Cooling Water and Stirring

Evacuation (critical step)

Heating and Distillation

Shutdown (key to preventing suck-back and breakage)

Care & Notes

Implosion protection

Anti-suck-back

Flammable solvents

Standard

Need This Apparatus Kit?

Vacuum Distillation Apparatus

Specifications

Component List

Product Description

1. Principle of Vacuum Distillation

2. Kit Composition and Function

3. Material and Workmanship

Applications

Natural product purification

Pharmaceutical intermediates

Fine chemicals

Petrochemical analysis

Food and flavour

Operating Guide

Safety Check and Preparation

Standard assembly order (bottom-up, left-to-right)

Cooling Water and Stirring

Evacuation (critical step)

Heating and Distillation

Shutdown (key to preventing suck-back and breakage)

Care & Notes

Implosion protection

Anti-suck-back

Flammable solvents

Standard

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Steam Distillation

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