What is the difference between simple, fractional and short-path distillation?

Simple distillation uses a flask, a still head and a condenser, and is used when the components differ in boiling point by more than about 25 degrees Celsius. Fractional distillation adds a packed or Vigreux column so repeated vapour-liquid equilibria separate components with closer boiling points. Short-path distillation uses a compact head with the condenser built into the still head, so the vapour travels only a few centimetres before condensing; it is the usual choice for heat-sensitive or high-boiling material under vacuum.

Which joint size should I order for a distillation kit?

Match every piece in the train to one joint size, normally 24/40 or 29/32 for laboratory scale work and 14/20 for micro scale. The flask, still head, condenser and receiver adapter must all be the same size, because a mismatched joint needs an adapter and each adapter adds a leak path and a hold-up volume. Order the train as a set where possible and confirm joint size on the packing list before the first run.

Why does my vacuum distillation bump or foam?

Bumping usually comes from superheating: the flask is heated faster than nucleation can keep up, or the pressure is dropped too quickly. Add a magnetic stir bar or boiling chips, apply vacuum slowly with a bleed valve, and raise the mantle temperature in small steps while watching the head temperature. Foaming is more often caused by dissolved gas or a wet sample and is reduced by degassing the liquid before heat is applied.

Does JWRESEARCH supply distillation apparatus in Singapore?

Yes. JWRESEARCH supplies borosilicate 3.3 distillation flasks, short-path and fractional still heads, Vigreux and packed columns, Liebig, Graham and Allihn condensers, receiver adapters, cow receivers, vacuum take-off adapters and heating mantles, delivered across Singapore with joint-size matching support.

Distillation Apparatus and Short-Path Glassware Singapore

Published: {{NEW_ARTICLE_DATE}} | By JWRESEARCH | Category: Laboratory Glassware

A distillation train is only as good as its weakest joint. The flask, still head, condenser and receiver have to be one continuous, sealed path, sized so that vapour reaches the condenser before it cools and so that liquid drains without pooling. Choose the wrong head for the separation and the cut smears; choose the wrong condenser and product escapes into the pump.

At JW RESEARCH SUPPLY, we supply distillation glassware in borosilicate 3.3 to chemistry, pharmaceutical, flavour and fragrance, petrochemical and teaching laboratories across Singapore. This guide covers the three common configurations, the parts that matter, and the specification points to check before ordering.

Choosing the Configuration

Simple distillation suits a clean separation between a volatile product and a non-volatile residue, or between liquids more than roughly 25 °C apart in boiling point. Fractional distillation adds a column between the flask and the still head, providing surface for repeated condensation and evaporation so that close-boiling components separate into sharper cuts. Short-path distillation keeps the condenser inside the still head, cutting the vapour travel path to a few centimetres — the standard approach for heat-sensitive compounds and for high-boiling material distilled under vacuum.

Configuration	Typical Flask Size	Separation Power	Pressure	Common Use
Simple distillation	250 – 1000 mL	1 theoretical plate	Atmospheric	Solvent recovery, rough purification
Fractional distillation	250 – 2000 mL	5 – 20 plates with column	Atmospheric or vacuum	Close-boiling mixtures, essential oils
Short-path distillation	50 – 500 mL	1 – 2 plates	Vacuum, 0.1 – 10 mbar	Heat-sensitive or high-boiling products
Micro distillation	10 – 50 mL	1 plate	Atmospheric or vacuum	Small or costly samples, method development

Specification Reference

Parameter	Typical Value	What It Affects
Material	Borosilicate glass 3.3	Thermal shock resistance and chemical durability
Joint sizes	14/20, 24/40, 29/32, 34/35	Seal integrity across the whole train
Condenser types	Liebig, Graham coil, Allihn bulb, Dimroth	Cooling capacity for the vapour load
Jacket length	200, 300, 400 mm	Residence time and condensation completeness
Column types	Vigreux, packed, spinning band	Number of theoretical plates
Receiver options	Round-bottom flask, graduated cow receiver	Cut collection without stopping the run
Vacuum rating	To 0.1 mbar with appropriate joints	Boiling point reduction for sensitive material
Max working temperature	Up to 200 °C at the flask	Mantle setting and thermal stress

Parts of the Train

The distillation flask sets the batch size and must never be filled above about two thirds of its capacity, because the liquid expands and foams as it boils. Round-bottom flasks with a single neck are standard; a two-neck flask allows a thermometer or capillary bleed without disturbing the still head.

The still head determines the vapour path. A simple still head takes off at 75° or 90°, a short-path head integrates a cold finger or jacket so the vapour condenses almost immediately, and a fractional head carries the column and a reflux splitter. For vacuum work, the take-off adapter must have the vacuum port on the pump side of the condenser so that condensed product is not pulled toward the pump.

The condenser has to remove the latent heat of the vapour at the rate it arrives. Liebig condensers are adequate for small simple distillations, Graham coils give more surface in a short body, and Dimroth condensers are the practical choice for high vapour loads or low-boiling solvents. Cooling water should enter at the lower port and leave at the upper port so the jacket fills completely.

The receiver completes the train. A single round-bottom flask is fine for one cut; a cow receiver with three or four positions lets you change fractions without breaking vacuum, which matters when the product is air- or moisture-sensitive.

Setting Up a Vacuum Distillation

Assemble the glassware dry, check every joint, then apply a light grease film only where the joint is not in contact with product. Clamp the flask, head and condenser separately to the same frame — never let the condenser hang from the head. Connect the vacuum through a cold trap, and use a bleed valve to bring the pressure down slowly; a fast pressure drop is the most common cause of bumping.

Heat gradually and watch the head temperature rather than the flask temperature. The head temperature tells you what is actually distilling; the flask temperature only tells you how hard you are pushing. Once the head temperature stabilises, hold conditions and collect the cut, then change receivers before raising the temperature for the next fraction.

Before You Order

Confirm one joint size for the entire train, or order the matched set.
Choose the condenser by vapour load and solvent boiling point, not by price.
Check that the receiver volume is at least half the flask volume.
For vacuum use, specify a cold trap, a bleed valve and a gauge you can read at working pressure.
Add boiling chips or a stir bar, and a mantle sized to the flask rather than to the largest flask you own.

Cleaning and Storage

Disassemble only after the apparatus is cool, and separate joints with a gentle twist rather than levering them apart. Rinse with the carrier solvent first, then detergent and water, and dry inverted. Store short-path heads and condensers in their original foam or on a padded rack; a chipped joint is enough to make an otherwise sound head unusable under vacuum.

Contact JWRESEARCH

JW RESEARCH SUPPLY — laboratory equipment and consumables, Singapore.
Telephone / WhatsApp: +65 8039 3660
Email: SINGAPORE@JWSHY.COM
Website: www.jwresearch.cn