Confined Space Ventilated Entry Procedure
Step 1 Verify that the only hazard present in the PRCS is an actual or potentially hazardous atmosphere. This means that no significant chemical, electrical, trip and fall, or other hazard is known to exist inside the PRCS. Nor is an ordinary condition made more hazardous by its combination with a confined space. Ensure there are reliable means to summon help: test your radio or telephone.
Step 2 If there is an entrance cover, eliminate all conditions (pressure, heat, smoke, etc.) which make it unsafe to remove the cover. Then remove the entrance cover and store it in a safe place.
Step 3 If the space is below the working surface, guard the entrance using a railing, barricade, or other temporary means to prevent an accidental fall through the opening and to prevent foreign objects from falling in.
Step 4 Check the internal atmosphere with direct reading, calibrated instruments for oxygen content, flammability, and for any toxic material potentially present. See Atmospheric Testing of Confined Spaces for more information. (The characteristics of the air in this initial test can give you a good indication of the existing or natural processes that may degrade air quality during entry.)
Step 5 Establish forced-air ventilation so that it ventilates the intended work area, and ensure that it is maintained until all personnel have left the PRCS. Ensure that ventilation failure will be indicated by reliable means. If ventilation fails, evacuate the space immediately.