E. 1. Head and D. Pavone
10s Alamor Scientific Laboratory (University of Colifornial New Mexico
II
Modification of a Vacuum Desiccator
In order to facilitate the removal of vacuum desiccator lids a simple device was constructed to eliminate the difficulty normally encountered in this step. Although simple in appearance this device has proved to he extremely helpful in application. An alnmim~mring (see figure) was machined such
DESICC4TOR L I D
M E T 4 L RINGWIO-RINOS
DESICCATOR
316 / Journol of Chemical Education
that its od and id corresponded to that of the ground surface of the desiccator. Into this ring were machined two O-ring grooves, one on each of the flat surfaces of the ring. This ring was then fitted with O-rings and inserted between the ground surfaces of the desiccator and its lid. During evacuation the O-rings are compressed until the flat surfaces of the ring contact those of the lid and desiccator. After the pressure inside of the vacuum desiccator has been increased to atmospheric pressure, the lid may be lifted easily from the surface of the O-ring. Ry cutting the grooves with different radii so that the top groove in the ring does not lie directly over the hott,om groove, the thickness of the ring may be reduced. A more desirable design would be to have the Oring groove formed into the ground surface of t,he desiccator during its fabrication. The technique described here has also heen used to facilitate the removal of the belljar housing the nen. Ainsworth vacuum balance. Ainsworth is now supplying this modification with a matching helljar for purchasers of their earlier vactnlm halancer.
