Water hammer breakage of glass containers may occur whenever a heavy object is dropped a few feet upon a packed carton placed so as to permit a short downward movement of the jars. This commonly occurs when one carton is dropped upon another in loading & stacking. When the top of the carton is struck, the jar is suddenly accelerated, forming cavities between the contents and the bottom and compressing the gases in the headspace, thus imparting a velocity to the contents, and finally causing the contents to overtake the bottom of the jar with a sharp impact. Accurate tests on the water hammer strength of jars are difficult because several factors, including the testing machine, the nature and location of adventitious flaws in the glass,& the nature of the contents, can seriously influence the results. These papers look at developments to reduce such breakage.
