Tham khảo tài liệu 'gas station construction and maintenance, petroleum systems contractor nevada and arizona_10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Simpo PDF Merge and Split Unregistered Version - http UFC 3-460-03 21 JANUARY 2003 fuel sludge and displaced vapor in a way that will reduce the possibility of any hazardous condition toxicity asphyxiation fire explosion inside the tank and in the surrounding area. . Ensure eductor-type air-movers have been operating continuously until the tank is safe to enter. Operate eductors for at least one hour or until LEL and oxygen are within safe limits immediately prior to entrants entering the tank and throughout the operation to maintain a safe explosive level. . Everyone entering must wear an approved supplied air respirator SAR with emergencyegress SCBA until the tank is declared hazard-free as specified in AFOSH Std 48-137 Paragraph . . All tanks being cleaned or repaired must be considered explosive until all sludge and loosely adhering rust and scale has been removed regardless of the type of stored fuel. . All tanks being cleaned or repaired must be considered leaded unless positive proof exists that the tank has never contained leaded fuel or the tank has been coated using the Air Force standard epoxy tank-coating system and has not held leaded fuel since. Before tank entry is authorized without PPE the LEL reading must be zero oxygen levels between and and lead benzene and other toxic material levels within safe limits. Refer to API Standard 2015 for additional information. . Atmospheric Testing. . Temporarily stop ventilation and perform vapor testing from outside the tank. Test the interior of the space by extending a hose and sample probe within 152 millimeters 6 inches of the tank bottom. Repeat every fifteen minutes for the duration of the operation. See AFOSH Std 91-25 Paragraph for testing sequence. Workers may enter the tank when vapor levels are below 10 of LEL if they are equipped with approved SAR with emergency SCBA. Never enter a tank without proper respiratory .
