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SELF-CLOSING LABORATORY VALVE D. T. ROGERS
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Rensselaer Polytechnic Institute, Troy, New York
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N THIS laboratory large quantities of sodium hydroxide (16 pounds of NaOH to make 20 liters of solution) are made up for student use. This alkali cannot be stored in aspirator bottles and siphons with rubber-tubing-pinchcock arrangements are frequently left open. The simple valve described in this article, made from ordinary soft steel, has proved quite satisfactoty for this purpose. These valves have also been made from stainless steel which undoubtedly will prove much more satisfactory. As yet the valves have been used only on siphons but they will retain liquids a t pressures up to 150 pounds per square inch. Figure 1 shows the exterior features of the valve. Part (A) of the valve handle encircles the siphon pipe, being held in place by the tension in the spring. Part (B) of the valve lever consists of a right-angled bend which strikes the pipe below the valve when the valve is fully opened and limits the movement to a quarter turn. This type of handle eliminates the usual pinstop arrangement which is easily sheared off. In Figure 2, part (C) is the coiled spring which closes the valve. One end of this spring is embedded in the body of the valve, the other in part (F) in which the spring is contained. (D) represents a cross-section of the valve handle which goes through the valve core and (I?), and which serves to hold the parts of the valve in place. The hole in the valve and (E) in the
core are small so that if for any reason the spring does not return the core fully to its closed position, liquid will not escape. A washer (not shown in the diagram) is placed between (F) and the body of the valve.
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FIGURE 2
Whenlthe valve is used for alkali, the inner diameter of the pipe a t the delivery end is reduced in size so that the pipe below the valve is always filled with liquid. The valves were made by A. Bigelman, 1314 Third Avenue. W a t e ~ l i e t New , York.
