Confined spaces present a number of dangers. The most common is the atmospheric hazards. Atmospheric hazards include lack of oxygen, oxygen enriched environment, levels of explosive vapors and toxic pollutants.
Oxygen
An oxygen-deficient environment, which is less than 19.5 percent oxygen. Low levels of oxygen in an enclosed space can be caused by a number of conditions, including chemical reactions in the sewage or other decomposing organic material(For example, plants and leaves) or oxidation of metals (eg rust). A deficiency of oxygen in confined spaces should never be without a respirator that supplies air to the user entered.
Oxygen-enriched atmosphere is one in which there are more than 23.5 percent oxygen. Oxygen-enriched environment dangerous, because it ensures that burn flammable and combustible materials, such as clothing and hair, violently if ignited. For this reason, pure oxygen should not be used for non-Ventilate a confined space, a combined space must be ventilated with ambient air.
Flammable atmospheres
To develop flammable atmospheres, as the result of an accumulation of flammable vapors in a confined space. Methane, a product of some types of decomposition, is a common flammable vapors in confined spaces found. Even if a flammable vapor is present, is in a range of concentrations that allow you to turn, because there is a danger to his will. Below a certain chemical / oxygenmix, there's fire. This is known as the lower explosive limit (LEL). On the contrary, above a certain chemical / oxygen mixture, there is too much to come from a chemical vapors and too little oxygen for ignition, ie the upper limit of explosion (UEL). Between the LEL and UEL, there is a risk of ignition, when a source, like a spark or flame is a fire or explosion may occur. According to OSHA, a confined space is safe if a fuel gas is at a level higher than 10% of the currentLEL. Workers can not in an enclosed space in this condition. It must be downloaded to a safe level before the employee records.
Poison gas
Gases and vapors from a variety of sources. For example, the hydrogen sulfide and carbon monoxide from sewage and decaying organic materials are produced. Other sources of toxic atmospheres include leakage or discharge of chemicals in a confined space. When toxins exceed OSHA limits, then the confined space mustbe adequately ventilated and workers must wear respiratory protection.
Monitoring required
Air monitoring must be done before entering into a registration required confined space. For a minimum of oxygen, LEL, and a monitor.
Oxygen-oxygen must be tested before testing LEL. Most combustible gas meters need sufficient oxygen be present in order to obtain a reliable indication of LEL, LEL readings are not reliable in aoxygen-poor environment. As mentioned above, should the oxygen content from 19.5 to 23.5 percent. LEL when oxygen levels were tested, the tests must be completed for flammable gases and vapors levels. As mentioned above, when the levels of readings that are 10% or more of the show that LEL can not enter a confined space until it has aired to reduce the level LEL. Toxic Atmosphere When toxic chemicals that may be present in the room, such as carbon monoxide, hydrogenHydrogen sulfide and chlorine to be tested to ensure that the atmosphere is not dangerous. If contamination above safe levels, and the room must be ventilated so that the level of harmful contaminants or to reduce workers have adequate respiratory protection.
