Dreifuss (chemistry)
The tripod is used in the chemical laboratory. It is used for placing the contents of crucibles , steam trays, beakers or similar laboratory vessels over a wire mesh , a ceramic wire mesh (formerly asbestos wire mesh ) or in a clay triangle . Funnels (with or without a filter insert ) can also be inserted into a tripod to B. to drain liquids into a vessel in which the funnel cannot hold.
Execution, handling
Tripods are made entirely of iron because of their heat resistance and are coated with a relatively heat-resistant aluminum varnish, which provides a certain degree of rust protection, but only remains where the legs are not covered by the flames.
The number of legs guarantees three legs, even on laboratory tables with ceramic tiles and joints. In order to keep the tilting moment and the stiffness against deformation sufficiently large even when hot, the legs are made of round iron with a typically 8 mm diameter and are somewhat flared. One construction method has the legs welded to the horizontal ring at the top, which is made of the same material or similarly thick sheet metal. In another, dismountable design, the flat ring at the top is made of a somewhat more heat-resistant cast iron and has 3 thickenings with blind holes at the bottom, into which the legs are screwed hand-tight at a slight angle.
A slightly yielding ceramic wire mesh that even out the heat of the flame creates a good base for a glass vessel with a flat bottom on the tripod. A ceramic triangle is used to hold a conical-bulbous ceramic crucible in the flame .
A gas burner is usually set in the tripod so that it can be operated with the right hand and can be pulled out thanks to the hose loop.
An alternative to a tripod with an identical function is the typical cast iron tripod ring, which is attached to the tripod or tripod rod using a cross clamp.
use
The height of the tripods should be chosen so that the vessels to be heated and their contents can still be optimally heated by the flame of the burner (e.g. Bunsen burner ). A height of 220 to 240 mm is favorable for conventional gas burners.
See also
Individual evidence
- ^ Walter Wittenberger: Chemische Laboratoriumstechnik , Springer-Verlag, Vienna, New York, 7th edition, 1973, p. 17, ISBN 3-211-81116-8 .
- ↑ a b Gerhard Meyendorf: laboratory equipment and chemicals , people and knowledge Volkseigener Verlag Berlin, 1965, pp. 20–21.