1. Enclosed Spaces
Before entering a potentially dangerous space, the atmosphere within must be tested for oxygen deficiency, flammable gases or vapours, toxic gases.
A) Oxygen Deficiency
The surrounding air contains an average of 20.9% oxygen by volum. Before entering enclosed spaces, the atmosphere MUST be tested. The ox-measuring device warns optically and acoustically IF the oxygen content is less than 19% by volume, respectively, indicates more than 23% by volume.
B) Flammable Gases or Vapours
In deciding whether the atmosphere is safe for tank inspections depends on the gas concentration within the tank which is determined by means of an EX-Meter. A conccentration of 0 vol. % resp. 20% LEL (lower explosive limit = LEL) reading on a combustible gas indicator (EX-Meter) is desirable. EX-Meters warn optically and acousticlly when readings are unsafe. For Bunker tank inspections without SCBA, a gas concentration of 1 vol. % in conjunction with 19.5 vol. % of oxygen is acceptable.
The Ex-Meter, resp. Multigas Detector are both capable to provide accurate readings in this respect.
C) Toxic Gases
Occupational exposure limits provide guidance on levels of exposure to toxic substances which should not be exceeded. This level is much lower than the flammable limit.
The presence of e.g. CO, CO2, NO, NO2, NH3, SO2, CL2, HCL, HCN in the surrounding air can easily be determined with Detector Tubes or with a TOX-Meter.
Resolution A.846(20) refers on entering enclosed spaces
하이그라파
