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Types and Forms of Laboratory Tweezers

The Single Burette Clamp

A common type of laboratory clamp is the burette clamp, which is used to secure one or two burettes in a holder for convenient experimentation. Although popular in other chemistry laboratories, the simple burette clamp is not sufficient for the organic laboratory.

The clamp is too short, and adjusting the angles with the “lock nut” (loosening the lock nut, turning the clamp jaws to the correct angle, and pressing the lock nut against the back stop, away from the jaws) is not much fun. If you are not careful, the jaws will slip and all the chemicals in your flask will fall out.

The Single Extension Clamp and Clamp Holder

This two-piece beast is the second best clamp. It is much longer (approximately 12″), so you can easily access complex configurations. By loosening the hand screw on the clamp holder, the clamp can be removed, pushed back or rotated at any angle. By loosening the screw on the ring holder, the clamp, along with the clamp holder, can be moved up and down.

The Three Finger Clamp

The three-finger (or 3-jaw) gripper is standard in most laboratories. These have a set of jaws or fingers that can grip and hold the glassware, and a cylindrical extension arm that allows for varying distance from the stand. They usually try to confuse you with two screws to tighten, unlike the regular extension clamp. This provides a little more flexibility, at the expense of a slightly more complicated form of configuration.

You can simplify life by opening the lower jaw two points at a 10-20° angle from the horizontal and treating that jaw as fixed. This will save a lot of wear and tear when setting up the equipment, but you can always move the lower jaw if needed.

These come in a variety of sizes (usually small, medium and large):

The small size is typically used to hold small, thin cylindrical items such as thermometers and temperature probes. The medium size is commonly used for small articulated glassware in sizes up to approximately 29/42 and can also support small capacitors in distillation configurations. The large sizes are often used to support vacuum lines, large apparatus and chromatography columns.

Other Specialty Clamps:

Rotating Thermometer Clamp

Holds glass tubes and thermometers 114 mm from the support bar. The clamp features safety adjustable spring plate jaws that adjust to any angle with a locking wing nut. The built-in bracket holds rods up to 19 mm in diameter. Lightweight, rust and corrosion resistant.

Water Bath Clamps

It holds a variety of devices, including glass tubes and thermometers in water bath glass walls. The built-in bracket holds walls of various thicknesses, up to 9 mm. The knurled screw tightens the jaws to hold objects securely.

Chain Clamps

Hold large round or irregularly shaped objects firmly, but gently, to laboratory racks and rods. Fast and secure sliding chain connection with large, easy-to-rotate adjustment knob.

Column Clamps

These sturdy, easy-to-adjust, multi-purpose clamps are ideal for holding large cylindrical glassware and similar objects. A large, flat screw or worm gear allows for maximum tightening or removal in a minimum amount of time. The clamp is constructed of corrosion-resistant stainless steel. Ideal for chromatography columns.

Nester Extension Clamps

Safely holds large or small glass distillation columns and oddly shaped glassware. Built in stainless steel with strong chrome-plated brass band and chain.

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