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1.7 SAMPLING PROCEDURE FOR MANHOLE ATMOSPHERES
The detector must first be operated in fresh air. The MSA Altair 5X will continuously and simultaneously monitor Oxygen, Carbon Monoxide and combustibles.
STEP 1
Observations of the atmosphere in the manhole shall be made at a level approximately two feet from the top, near the middle of the manhole, and at a level near the bottom. If water should be present in the manhole, the latter observation should be made at a level just above the surface of the water. Care should be taken not to immerse the end of the sampling hose in water. When exposed to water, the filter at the end of the sampling hose will automati- cally close to prevent any material or gas from enter- ing the tube.
STEP 2
Insert a ladder into the structure and take samples around the casting and chimney. While descending the ladder, take samples to the right and left for three levels.
STEP 3
Check the remainder of the manhole from the tested area.
STEP 4
Check remaining area at duct edges, corners, cracks, and other irregularities.
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