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Equipment

Hoffman Clip

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Fig 1: Hoffman clip
Fig 1

Summary

A clip used to seal flexible tubing.

Operation

Hoffman clips may be referred to as just 'tube clips' in lab catalogues and may be of a number of slightly different designs.

Most clips are of a square construction, usually made from a plated nickel which should keep them corrosion free for a long time. The bottom plate of the clamp is removable or at least can swivel on one side allowing a tube to be inserted between the moving and stationary plates.

At the top of the clip is a threaded bar with thumbscrew which when turned, allows the moveable plate to push down on the tubing, causing the flowing liquid within the tube to cease.

Things to be aware of:

  • Keep dry when not in use as acids and chemicals may speed up corrosion of the threaded bar, shortening lifespan.
  • Try to buy plated clips of a sturdy nature. They will last longer than unplated or cheaply constructed clamps.
  • Never use pliers or other tools to tighten the screw thread. Over-tightening may damage the threaded bar.
  • If connected to tubing, especially rubber tubing for a long period, move the lamp slightly from time to time as not to put pressure on one specific part of tubing which could lead to wear.
Various types of Hoffman clip are available for various thicknesses of tubing. Most lab suppliers stock Hoffman and Mohr clips. Both are used for clamping flexible tubing.

Safety

 CautionThe contents of this page are for information only. Please refer to CLEAPSS or ASE safety advice and/or publications before undertaking any preparation, practical experiment or using any equipment featured on this site or any other.