Abstract
Accuracy of the measurement of the vacuity in cans by the dial vacuum indicator has often been reported(1)(2) by one of the authors, but any comparison with that of the tapping inspection has never been made.
In this experiment we have made a comparison between them, taking as the test cans about eight dozens of flat no. 1, 1 lb salmon cans.
The results of the experiments are shown in Figs. 3, 4 and 5. The average deviation of the tapping inspection value from the actual vacuity measured by the ordinary piercing vacuum gauge is 4•38 inch in mercury column as shown in Fig. 3 the υ-υT diagram, and that of the measured value with the dial vacuum indicator is 4•24 inch as shown in Fig. 4 the υ-υD diagram.
As the standard vacuum scale of the dial indicator in this case, we adopted the mean straight line of the measured points on the υ-β diagram (vaccum and end depth diagram) which h ?? d been obtained as the results in the previous experiment on another group of flat no. 1, 1 lb salmon cans(3). This standard scale line is shown by the straight line A0 in Fig. 5 the υ-β diagram. The straight line A in the same figure is the mean line of the measured values of this time expressed in the can end depth.
By the tapping inspection it is said that not only the vacuity in cans is presum ?? d, but the relation between the volume of the heardspace and the weight of the net content of cans, the tightness of the seams are decided and flat sour cans are also detected with only talent and experience, but we have found by this experiment the same accuracy of the measurement can be obtained by the dial vacuum indicator, wi ?? h the simplest instrument and with the speediest operation which does not n ?? cessitate any talent, experience nor skillful ?? ss so far as only the vacuity is concerned.
