INDUSTRIAL A N D ENGINEERlNG CHEMISTRY
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( 2 ) Longitudinal seam riveted lap joint For vertical cylinders, a = 70 For horizontal cylinders, a = 100
The constant c is intended to thicken the material to care for losses due to corrosion, erosion, and similar factors, In common boiling kettles Bach gives c the value 0. HausbrandJ5using the same values for k for iron and copper in this equation, makes up the differences between the two metals by varying the value of c. Thus he gives c, for iron, a value of 2.0, and for copper of 0.2 (6-s), and in calculating on this basis gets thicknesses for iron greater than for copper to withstand the same pressures. Obviously, this renders the values given in his book inaccurate for general use. Assuming values for ratio of length to diameter, l / d , and for the constant, n, curves may be plotted for pressure against 6
“Hilfsbuch fur den Apparatenbau.”
A Clamp for Rubber Tubing’ Harold W. Batchelor 0x10 AGRICULTURAL EXPSRIMSNT STATION,WOOSTSR,OHIO
H E following method of clamping rubber tubing to glass tubing for general laboratory apparatus or for pressure or vacuum systems has been found very satisfactory. A sleeve, c, approximately 11/2 inches (3.8 cm.) long may be made of thin glass tubing whose inside diameter is but slightly larger than the outside diameter of the tubing to be used. The sleeve is first slipped several inches on the rubber tubing. The tubing is then slipped into place on the glass tubing, a. While holding both the glass and the rubber tubing at b, the latter is stretched slightly so that it assumes the position indicated by the dotted lines a t d. The glass sleeve is then put in position and the rubber tubing worked back into position as shown by the heavy lines a t d. When the rubber tubing has been properly worked into position, the clamp is so effective that it is practioally impossible to remove the tubing when pulling a t b. By stretching the tubing again a t d and removing the sleeve, the two tubes can be easily separated again. Though not usually 1
Received February 9, 1928.
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Vol. 20, No. 4
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the ratio of thickness to diameter, s/d. The accompanying Figures 2, 3, and 4 give values for copper tanks on the supposition that c = 0. The designer should bear this in mind in adapting these curves for use under conditions which will require greater wall thicknesses than those calculated. I n using these curves for aluminum work the value obtained from the curve for the required condition is multiplied by 2.0. For iron the value obtained is divided by 1.5. The curves may be similarly adapted to use with other metals by making proper allowances for differences in tensile strength. In designing a cylindrical tank, the practical minimum of labor and materiale is attained when I = ?T d. I n general, vessels having a ratio of length to diameter between 1 and 4 are most economical to design and build from all practical points of view. 6
Chem. Met. Eng., 84, 379 (1927).
necessary, the clamping effect may be increased by slightly widening the end of the glass tubing a t e. If the clamp is used in the construction of gas-analysis apparatus, a mercury seal would scarcely be necessary, since the rubber tube is clamped uniformly throughout its circumference. The clamp may be modified, horvever, to form a cup for a mercury seal as shown a t f. A mercury seal to connect two rubber tubes can be easily prepared by welding a side arm a t the midpoint of the sleeve. Such a cup can be used either with a straight side arm in a horizontal position or in a vertical position with the side arm bent to a vertical position. The sleeve also affords an e x c e l l e n t protection for the rubber tubing if it is necessary to wire it in position on a base as shown. It is hoped to make available in the near future either metal or other tubes for this purpose.
