valve 5, closing the valve on handpump 3, and then pumping on handpump 3 until 

 the intensifier piston is returned to the bottom of its stroke, indicated by the re- 

 lease of hydraulic fluid from release valve 7 . The second upward stroke is then 

 accomplished by a repetition of the procedure for raising the piston, described 

 above , The pressure can be reduced in a controlled manner by opening drain 

 valve 4. 



The high-pressure vessel is shown in Figure 5 . It is a jacketed or 

 compound cylinder of tapered shrink construction. Since in a vessel of this de- 

 sign the inner cylinder is in compression and the outer one in tension, very great 

 strength results. Bridgman's "shrunk-on" method of supporting tapered vessels 

 is based on the same mechanical principle .''*) The hydraulic fluid is transmitted 

 through the bottom of the pressure vessel. From the closure, the conductivity 

 cell is suspended in the vessel's cavity, which is 9-3/8 inches in length and 1 inch 

 in diameter . In order to reduce the total volume of fluid which must be compressed, 

 the remainder of the vessel's cavity is filled with a loose-fitting filler-bar. This 

 filler-bar must be crosscut in the bottom to prevent it from acting as a check valve. 



Figure 6 shows an enlargement of the closure of the pressure vessel. At 

 moderate pressures the mild steel ring and the lead back-up ring extrude and act 

 as seals. One electrical lead is sealed with a cone and is insulated. The closure 

 itself, which is in electrical contact with the remainder of the high -pressure equip- 

 ment, acts as the second lead , The outside lead from the closure must be con- 

 nected to the grounded terminal of the conductivity bridge. 



2 o Safety Precautions 



On all sides of the high-pressure apparatus not protected by the equip- 

 ment's steel-plate cabinet, a movable sectional shelf of a " Ho mo sote" -plywood 

 sandwich was erected. Personnel on the floor above were protected with a 1-inch 

 steel plate mounted on a strong frame directly above the closure . A laboratory 

 shower and additional dry-chemical fire extinguishers were installed, warning 

 signs were posted, and face masks and gloves were provided. As an added safety 

 precaution, a special, less flammable hydraulic fluid was obtained, (See below.) 



3 , Hydraulic Fluids 



White gasoline is commonly used as the hydraulic fluid in high-pressure 

 equipment. As a safety precaution, we used a less flammable fluid (Univis P-38) 

 for runs at less than 100, 000 psi, Univis P-38 (Humble Oil & Refining Co.) is an 

 ester-type hydraulic fluid which was developed for military aircraft and large gun 

 recoil mechanisms . Unfortunately, it becomes highly viscous and therefore un- 

 usable above 120, 000 psl. 



:artbur m.lltttlejnt. 



S-700 1-0307 



