B24FA 



■OUT OF VESSEL 

 ■IN VESSEL (0 PSIG) 

 ■IN VESSEL (500 PSIG) 



120 



illO 



ilOO 



90 







/^\ 



■^ 







vvr*. 

 .•v\. *• 



A*. 



\V , 



1 









\ / 















15 



20 



25 30 



KC/S 



35 



40 



Transmitting response therefore is markedly dif- 

 ferent at 500 ps i g . 



CONCLUSIONS 



The acoustic pressure vessel can be used on the 

 regular calibration column for testing frequency response, 

 directivity, and impedance of transducers. Water pressure 

 can be controlled to any value up to 800 psig. The effect 

 of the presence of the vessel is negligible for frequencies 

 below 8 kc/s and predictable for frequencies up to 1 Mc/s. 

 Calibration can be accomplished by cw or pulse at lower 

 frequencies; however, pulse technique must be used above 

 8 kc/s for accurate readings. 



17 



