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<br />001G96 <br /> <br />Appendix D , <br />PROCEDURE FOR VERIFICATION TESTING <br />OF HYDRAULIC CYLINDERS <br /> <br />Navajo Dam 72-inch Ring-Follower Gates <br /> <br />(ROD END AMPLIFICATION TESTING) <br /> <br />Revision 2 (7/22/98) <br /> <br />EXPLANATION OF TEST <br /> <br />Checking for piston seal leakage can be accomplished by viewing the effect of bypass - <br />flow around the piston in the hydraulic cylinder on the rod speed. <br /> <br />DANGER - Do not rod end amplify the hollow-jet valves. Make sure they are valved <br />off from the hydraulic system during the testing. <br /> <br />The test should be performed every 6-inches of gate movement. It verifies the <br />cylinder's and piston ring's sealing capabilities, thereby assuring full power will be <br />available to the gate at all positions. <br /> <br />Only one pumping unit in the hydraulic power unit should be energized for this testing. <br />The travel of the rod can be measured at the access port in the bonnet cover. A ruler <br />should be temporarily mounted close to the shaft. A marker is used to mark the initial <br />position on the shaft and another individual records the time. This information can be <br />recorded in the attached table. <br /> <br />To check for piston leakage, the shutoff valve in the rod side of the cylinder will be <br />used. It must be capable of sealing. With the valve closed and the piston bottomed <br />against the cap end of the cylinder, the cylinder will be subjected to full system <br />pressure of 1800 p.s.i. The valve is then cracked open which allows the cylinder to <br />move a short distance along it's stroke. The valve is then closed. At this point, full <br />system pressure will act on the major area (top) of the piston. which results in an <br />intensified pressure on the bottom of the piston. The seals on the piston are then <br />subjected to this differential. In the ring-follower system, with 1800 p.s.i. on the top of <br />the cylinder, the rod side will experience 2037 p.s.i. Fluid leakage across the piston <br />will transfer from the rod side of the cylinder to the cap end of the cylinder and the rod <br /> <br /> <br /> <br /> <br />. <br />