is virtually eliminated if "useless" short lengths of tubing are used. While cork may withstand higher temperatures than rubber, very hot flasks should never be placed on either type of ring.
Reducing Funnel Breakage Gary Sprague MBdford Senior High Schwl Medlord, OR 97504
We have found the followingimprovisation helpful in preventing breakage of long-stem glass funnels in our chemistry labs. Since most of the hreakage occurs when funnels fall over onto a table top, we looked for a way to eliminate the shock of the stem when it hits. This was accomplished by placing a short length (1 em) of latex tuhing, 31s-in. inside diameter, 'Ia-in. wall thickness, on the end of the stem. Actually, the tubing size is not critical so long as i t fits the stem, is thick enough to absorb the shock, and prevents hreakage. The tuhing is positioned on the stem without covering the tip so that the tubing does not become contaminated with chemicals during funnel usage.
selection of flask holders made from (clockwisefrom bottom left) plastic lids, rubber tubing, and a polyethylene bonle. Figure 1 . A
Toroldal Flask Holderss Tublng
Typea T T
P P
P P
P P
,anglh (em) 12-13 13.5 15 17 20 23 27 30
inside Diameter ol Term (cml
Capac;ly ol FlashC (dm3)
triangle lriangle
0.01 0.025 0.05. (0.1) 0.1. (0.25) 0.25. 0.5 0.5, 1, (2) 1.2. (5)
3.5 4.5 5 6 7 8
9 5
'Small flasks (50.025dmS)are top hsavy due to t h l r high center of gravify. = thln-wailed (outside diameter = 1.0 cmJ: P = pressure (outside diameter = 1.4
cm).
ParenVUIsas indlsato an ananate nadk size mat may be wed with me ring size.
Plastic Bottles (suitahle for flasks from 25 to 500 cm3 capacity). Old plastic bottles may he utilized by slicing them into sections (as shown in the Figure). The height of each section depends on the diameter of the bottle, the rigidity of the ~lastic.and the size of flask to be sunnorted. A straight cut was bhtainid by using a ruhher handas a guiding mark. Short lengths of ruhher tubing- were added (as shown in the ~ h o t o graph). Rubber Tubing (suitahle for flasks up to 20 dm3 capacity). This was found to be the quickest and most effective method. A suitahle length of rubber (preferably pressure) tubing (see Table) is cut and the ends joined. A variety of connectors can he used. The best tvDe is a tube with enough .. rigiditv .. . to be pushed inw ruhher'khing hut still flexible enough ro Iwnd slirhtlv. Thr t t ~ t n !froma rhstic wash hottlr isa cowl exsrn~le. ~ i torus2 e thus formed provides a non-slip &face and also cushions a flask when i t is put down. Such a rine (internal diameter 15.5 cm) formed from 2-cm tuhing can support a 20dm3 flask at all angles. The cost of these rings was found to he approximately one-third the price of the corresponding cork rings. This cost
F a very small flasks(525 cm3)the torus is shaped intoa triangle. The flaskscan be suppwted only wilh the neck vertical due to their high
la) funnel.lb) bumDer made from latex Funnel with rubber bumper: . . long-stem . tubing. (c)approximately % cm of stem remains exposed.
I I
This column reorasemsa consolidation of me ADDaratus Review and nllaltm Foghlers IeaNes um(l a wg1. e d m x ~ hp Reader9 w II continue to tono bsetui aspects of ban. mcld cq mrmds and deta b of how lhey can save money by building their own equipment, and information on and evaluations of currently available equipment, apparatus, and supplies. Novel, timesaving, or cost-saviag techniques also will be shared in this feature. Readers Interested in contributing to this feature should contact the feature editw.
center of gravity. Other flaskscan be supported at any angle.
Volume 61
Number 4
April 1984
389
