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POTENTIAL PROCEDURES FOR HAZARD <br /> HAZARDS REDUCTION <br /> 7. Existing manholes sub 7 . The- oxygen in confined <br /> surface vaults and sheds spaces must be monitored <br /> are confined spaces that with an oxygen meter <br /> may lack adequate prior to-"entry. If <br /> ventilation and trap oxygen monitoring <br /> organic and/or indicates that the level <br /> combustible vapors. To of oxygen is less than <br /> avoid anoxia from the 19.5%, personnel entering <br /> lack of oxygen and/or such spaces must wear an <br /> overexposure to vapors; air-supplying respirator. <br /> personnel entering these Oxygen monitoring should <br /> spaces must follow the be conducted at the top, <br /> procedure for reducing middle, and bottom of the <br /> hazards. The confined confined=space. <br /> space must be monitored <br /> for (a) oxygen level, (b) The presence or absence <br /> flammable vapors, , and, of explosive vapors must <br /> (c) toxic vapors. be determined before <br /> entering any confined <br /> space. If the explosi, <br /> meter .readings are <br /> greater than 20% of the <br /> Lower Explosive Limit <br /> .(LEL) , confined spaces <br /> must not,,be entered and <br /> the First Dept. should be <br /> notified. Note that the <br /> accuracy of explosimeters <br /> is compromised when used <br /> in atmospheres that <br /> contain less .than 19.5% <br /> oxygen. <br /> For monitoring toxic <br /> vapors, - which are organic <br /> in nature (i.e. gasoline, <br /> diesel) , a PID or FID may <br /> be appropriate. Toxic <br /> vapors may also be <br /> detected-by utilizing <br /> color-detector tubes <br /> (Draeger., S_ensidine, <br /> etc. . . ) . <br /> 11 <br />