Flask Boiling (Round Bottom) with Joint

This round bottom boiling flask has a single neck with a precision ground glass socket, and it's the basic building block for distillation, reflux and synthesis setups. It's made of borosilicate 3.3 glass and comes in sizes from 50ml up to 10 000ml, with a choice of socket sizes for each capacity.

The glass is high-purity borosilicate 3.3, with low thermal expansion and high resistance to chemical attack, and the flasks meet IS 1381 (Part I) and ISO 1773 for laboratory boiling flasks. The socket is a tapered female joint, such as 24/29 or 19/26, that gives a vacuum-tight, greaseable connection to condensers and other glassware. The flasks work up to 450°C and handle thermal shock well when you heat and cool them quickly.

Distillation is the most common use. The flask is the "pot" where the mixture is heated, and as it boils the vapour rises up the neck into a condenser. For reflux, a condenser sits on the neck so a reaction can be heated for hours without losing solvent: it boils, cools in the condenser and drips back into the flask. The round shape also suits synthesis work, since a magnetic stir bar or overhead stirrer mixes it efficiently, and the larger flasks go on rotary evaporators to strip off solvent gently under reduced pressure.

Why round? With no corners, heat from a mantle or oil bath spreads evenly through the liquid, so you don't get hot spots that could decompose the sample. A sphere is also the strongest shape against outside pressure, which is why round bottom flasks are the ones used for vacuum distillation, and why they're safer than flat-bottom flasks under high vacuum.

A round bottom can't stand on its own, so you'll need a cork ring to rest it on the bench, and a clamp on a stand to hold it by the neck while it's in use. Heating mantles are shaped to hug the curved base, and Keck clips hold the ground glass joint to a condenser or adapter.

Specifications

• Design: round bottom with one neck
• Material: clear borosilicate 3.3 glass
• Capacity: choose from the drop-down
• Socket: choose from the drop-down
• Printing: white enamel markings (acid and scratch resistant)
• Brand: OMSONS
• Product of India

Stoppers to fit (not included)

19/26 socket

• Solid rubber stopper: RS9-S 17x20x26mm
• 1-hole rubber stopper: RS9-1H 17x20x26mm
• 2-hole rubber stopper: RS9-2H 17x20x26mm
• Glass stopper: GRS6860/3 19/26

24/29 socket

• Solid rubber stopper: RS13-S 23x26.5x28mm
• 1-hole rubber stopper: RS13-1H 23x26.5x28mm
• 2-hole rubber stopper: RS13-2H 23x26.5x28mm
• Glass stopper: GRS6860/4 24/29

See the full range of solid rubber stoppers and one-hole rubber stoppers.