Document 1gnjYknB8Q5eeeEKO32kq3wpj

equipment must be kept a safe distance from the tank being cleaned Protective equipment Although full details on personal protective equipment can be found in Chapter 19, it is well to discuss specifics concerning tank clean ing here It is considered good practice to wear water tight rubber boots, thoroughly cleaned and m good condition, for tank cleaning It is ad visable to wear rubber or impermeable gloves, but, if the work does not permit their use, a protective cream recommended for the expo sure should be used In an atmosphere which is dangerously untant or corrosive to the skin, a complete outfit of impervious clothing must be worn Supphed-air hose masks with blowers and safety harnesses with lifelines, or self-contamed or self-generating breathing apparatus, must be wom by men entering tanks unless the person m charge has determined that the vapor concentration is below the threshold limit value (see Chapter 38, "Industrial Toxi cology") and that no oxygen deficiency exists If a test of the tank shows it to be deficient in oxygen, whether or not it is otherwise im mediately hazardous to life, the tank should be ventilated with fresh air and be checked for oxygen before entering with approved breathing apparatus This can be either a compressed-air type of self-contained breath ing apparatus, a self-generating type, or airsupplied type The fit of the facepiece should be carefully checked before the workman en ters the tank If the environment contains a substance that is dangerously irritant or cor rosive to the skin (lead tetraethyl, for ex ample), the breathing apparatus may be sup plemented by complete attire of impervious clothing Some medical authorities advise that indi viduals with broken eardrums not work in vapor-laden atmospheres, because no mask will protect these abnormal openings The supplied fresh air hose mask with blower is generally the best type of respira tory equipment for continuous use in a tank Proper procedures A tank should be free of gas before any work is performed inside it A worker should not be allowed to enter a gassy or oxygen-deficient tank unless abso lutely necessary, such as in an emergency When this is necessary, the man should be attended on the outside by another worker who is similarly outfitted with approved re spiratory protection and protective attire as needed so that the latter can rescue the man in the tank if necessary In some states this is a legal requirement Men engaged in tank cleaning should be instructed m the method of giving artificial respiration and should be retrained period ically If a tank cleaner is overcome by vapor or gas, he should be removed to fresh air im mediately and given artificial respiration until he resumes breathing A physician should be summoned, and the resuscitated man kept quiet and warm until breathing and circula tion are normal The sense of smell cannot be relied upon for an accurate estimate of the amount of flammable vapor present in a tank It does, however, give warning that vapors of some kind are present Symptoms of dizziness, nausea, and headache indicate that a danger ous concentration of flammable and toxic vapors is present Exposed workers should leave the contaminated area immediately and not return until vapors have been cleared Workers should always have a clear path of escape from a tank and should bear in mind that thev may have to use it m a hurry A ladder should always be used when a tank must be entered from above, and it should be left secured in place until the last man is out of the tank Under severe conditions, a life line is recommended to assist with rescue work Burning, welding, cutting, and spark-pro ducing operations should not be permitted in a tank until the area to be heated has been thoroughly cleaned and tests have determined that the tank atmosphere is vapor free Where any vapor is present, further ventilation will be required to remove it from the tank Hot work repairs (welding and cutting) should not be made whenever other means can be used more safely Even after a tank has been freed of vapor, combustible mixtures again may be formed through admission of flammable vapors or liquids from other sources, such as an unblanked line or con- 1315