737 
ae Sil ee 
12. Summary of RELIANCE instrumentation 
The instruments which give the greatest and most comprchensive infor- 
mation for measuring explosions from large charges are the piezoelectric 
gauges: and associated equipment, from which complete records of pressure and 
time may be obtained. However, this type of instrumentation is. very diffi- 
cult to maintain and operate as outlined in Sec. 7(e). 
In contrast with the piezoelectric gauges, as regards difficulty of 
operation, are the mechanical gauges, particularly the ball-crusher gauge. 
One man can handle as many as 2)-ballecrusher gauges on the vessel, and 
the measurement of the deformation of the copper balls can be done in the 
laboratory by other technicians, The Modugno and UERI-diaphragm gauges are 
somewhat more difficult to handle, expecially the latter, However, the 
UERL-diaphragm gauge has greater precision than the Modugno or ball-crusher 
gauge, so that not as many of them are required on each shot. These three 
mechanical gauges give very little information about the form of the shock 
wavee Only the ball-crusher gauge is capable of having its reading trans- 
formed casily itno peak pressure, and even this requires information re- 
garding the form and decay constant of the shock wave. 
The Hartmann momentum gauge, which integratcs the pressure—time curve, 
is more difficult to handle than the above mechanical gauges, and the com— 
posite Hilliar gauge, which gives a rough form of the pressure=time curve, 
is the most difficult of the mechanical gauges to operate, The amount of 
information obtained by the use of cach gauge is apparently in proportion 
to the difficulty of its operation. 
