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EXPLOSWITY ACTION LEVELS <br /> (% of the LEL)"' <br /> Instrument Calibration Gas Action Level <br /> (Evacuate) <br /> Combustible Gas Indicator hexane 20% <br /> Combustible Gas Indicator methane 20% <br /> *** LEL for gasoline is 1.3%. LEL for diesel/no. 2 fuel oil is 0.6% <br /> The CGI alarm must be set to sound at the action level. For this work it is highly <br /> recommended that hexane be used as the calibration gas. <br /> When measurements with a combustible gas indicator (CGI) indicate the presence of <br /> combustible gas levels equal to or exceeding the explosivity action level in the work area, <br /> the following actions will be taken: <br /> • Extinguish all possible ignition sources in the work area and shut <br /> down all powered equipment. <br /> • Move personnel at least 100 feet away from work area. <br /> • Contact HSO/HSC. <br /> • At the instruction of the HSO/HSC and after waiting 15 minutes for <br /> organic vapors to dissipate, the SSO may use the CGI to cautiously <br /> and with prudence approach the worksite to determine the extent and <br /> concentration of organic emissions. The SSO shall not enter any area <br /> where CGI readings exceed the explosivity action level, nor shall the <br /> SSO or PM make any approach if there is possibility of fire or <br /> explosion. <br /> • Personnel may reenter the work area only by clearance of the <br /> HSO/HSC after the cause of the emission has been determined and the <br /> source abated. CGI readings in the work area will remain below 20% <br /> LEL for 15 continuous minutes prior to resuming activity in the area. <br /> 90500000 H:\HEALTH\FNLHSP April 21. 1993 <br /> FEMA USTi Fr l Generic HSP 17 <br />