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 jointed glassware in sizes up to about 29/42 and can also support small condensers in distillation setups. Large sizes are often used to support vacuum lines, large apparatus, and chromatography columns.
The double-adjust 3-fingered clamps shown above feature a set of thumbscrews to adjust the jaws. As shown, these usually have wide pads to easily allow precise individual adjustment of either arm (the side with two fingers and the side with one finger). Some clamps have only a single adjustment and these usually feature a wing nut rather than thumbscrew. There is no real practical reason to chose single adjust over dual as the price difference is insignificant.
Two fingered clamps usually feature two broad fingers to provide support. These are available in both single and dual-adjust styles:
Regardless of style, a clamp needs a holder to connect the arm to the ring stand or laboratory frame support. Some examples of these are shown below. The one on the left is the most common and sufficient for most needs, but there are a variety of styles, including ones that swivel to accommodate just about any position (click on any item for more information and detail):
Some clamps even integrate the holders for special purpose situations or ease of use. Some examples include clamps for holding thermometers on the wall of a water bath and fixed-position clamps that while not adjustable, provide a repeatable clamping position every time:
Both work with an open-link chain. To use one of these, the user pulls the chain tight around the object and hooks the link that most closely matches the necessary circumference on a tang or catch. Tightening a thumbwheel or thumbscrew then pulls the chain tight, providing a firm grip.
Column clamps are basically a common radiator clamp affixed to an extension arm. One threads the slotted metal strip into itself and then tightens the clamp with worm gear using a thumbscrew or screw/nut driver depending on the model:
Round and square support plates are similar. The one shown here can be used to support a stirplate or heating plate.
This page was last updated Sunday, June 12, 2016.
This document and associated figures are copyright 1996-2017 by Rob Toreki. Send comments, kudos and suggestions to us via email.