Engineering and Contracting . e rubber facing on theclapper is either coated with slime, or somesmall indentations occurring, allow the waterto pass back through this valve. The conditions of tests are slightly different,depending upon whether a mill has one con-nection or two. If it has two connectionsthere is always present the city pressure fromthe other connection coming back to the twovalves; whereas, if there is only one connec-tion there is only the static head, or else thefire pumps in the mill are started, and pressurecreated in that way. If the flow from E or// is continuous, it is a
Engineering and Contracting . e rubber facing on theclapper is either coated with slime, or somesmall indentations occurring, allow the waterto pass back through this valve. The conditions of tests are slightly different,depending upon whether a mill has one con-nection or two. If it has two connectionsthere is always present the city pressure fromthe other connection coming back to the twovalves; whereas, if there is only one connec-tion there is only the static head, or else thefire pumps in the mill are started, and pressurecreated in that way. If the flow from E or// is continuous, it is an indication that thereis a leak either through both check valves orthrough the stop gate A. If the pressure withE and H open drops on G only, and not on /and M, it is the gate A leaking; but to makeabsolutely sure allow all the gages to assumethe normal pressure, and then suddenly re-lease F. If gages / and G drop, and M doesnot, and flow continues, then it is an indicationthat the leak is througli A, and not throughB and From PublicWater Pif>e5 To Fig. 1. Sketch Showing Double Check Valve Installation for Separation of Public andIndustrial Water Supplies at Auburn, N. Y., and Apparatus for Testing Valves. with medium hard rubber, and liberal clear- nce to be made all around the clapper, the n, the arm, etc. These specifications were rgely determined by the inspection dcpart- 1 nt of the Associated Factory Mutual Fire ^u^ance Companies of Boston, and they also h1 to meet with the approval of the water ?? partmcnt of the city of Auburn. The regulations are that they shall be listed once every six months by the water department and taken apart once each year , and examined for defects or obstructions, and during this latter inspection a representative from the .Associated Iactory Mutual Fire In- !ranee Company is present to observe the ? udition of the valve and assist at the is specified by the water department that the inspection and test shall be a
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