Standard Clamp Retort, Three Pronged, Rubber Lined

Quick Answer: The Standard Clamp Retort, Three Pronged, Rubber Lined is a rubber lined retort clamp: three fingers, lined with rubber on their gripping faces, close on glassware when the screw is turned. The listing photograph shows a bright body, red rubber-covered fingers and a straight rod for a boss head.

The Everyday Clamp of the School Lab

If a school lab owns one kind of clamp in quantity, it is usually a three-pronged clamp like this. It holds a boiling tube at an angle while it is heated, grips the neck of a conical or round-bottom flask, and steadies a thermometer or a delivery tube. The word ‘standard’ in the title marks it as the general-purpose pattern rather than a specialist condenser or burette clamp.

Three fingers close on a round object from three sides, so it cannot roll out of the grip, and the rubber lining adds friction on smooth glass while spreading the pressure. That lining is what lets a student tighten the screw enough to hold a tube firmly without the metal biting into it. Rubber does not tolerate direct flame, so hold heated tubes near the mouth, well away from the burner.

For large flasks and bottles, the jumbo three finger clamp opens wider. Replaceable push-on sleeves are the feature of the three finger clamp with rubber sleeves; on this model the rubber is described as a lining, and the listing does not say whether it can be renewed.

Applications

• Holding a boiling tube at an angle while a solid such as copper carbonate is heated in it
• Clamping a conical flask for a rate-of-reaction experiment with a gas syringe
• Holding a thermometer upright in a beaker for heating or cooling curve readings
• Steadying a delivery tube over a trough when collecting gas

Care & Handling

• Keep the rubber lined retort clamp near the cool top of a heated tube, never over the flame.
• Tighten until the tube or flask cannot turn, then stop.
• Check the rubber for cracks and hardening each term; hardened rubber grips poorly.
• Keep oils and organic solvents off the rubber, which they swell and soften.

Specifications

Why Choose LabEquip

Schools usually order three-pronged clamps in class sets, one per stand plus a few spares. LabEquip lists this standard clamp with boss heads and stands in General Lab Products.

Frequently Asked Questions

What does the rubber lining do?

It grips smooth glass and spreads the clamping force, so glassware can be held firmly without bare metal scratching or cracking it.

Where should I clamp a boiling tube for heating?

Near the mouth, roughly a third of the way down from the top, with the tube angled and its mouth pointing away from everyone. The clamp then stays clear of the flame.

Can the clamp hold a round-bottom flask?

Yes, at the neck, where three fingers seat well. Do not clamp the bulb, and support larger flasks from below as well.

Why use three prongs rather than two?

A round item held at two points can roll out when knocked; three fingers surround it, so it stays centred and cannot rotate out of the grip.

What damages the rubber lining?

Heat, oils, many organic solvents, ozone and sunlight. Store clamps in a drawer and clean the lining with water and mild detergent only.

How does it differ from a condenser clamp?

A condenser clamp is designed around the long, wide jacket of a condenser. This standard clamp is the general holder for tubes, flask necks and small vessels.

Last Updated: September 2026