Document ZJKwnGQa0w1Q0yG68nJM0xbL7

1002 CHAPTER 43 1956 Guide Rectifiers have generally proved to be the most practical m^ans for supplying the necessary current for protection of surfaces in contact with neutral waters.40 HANDLING WATER TREATING CHEMICALS Virtually all the chemicals used in water conditioning are injurious if taken internally in large doses. Many also cause severe skin irritation. Thus, they should be handled with caution. Caustic soda, lime, and concentrated sulphuric acid will bum the flesh. In addition, if mixed with small amounts of water, sufficient heat may be generated so that spattering occurs or the container becomes too hot to handle. The chlorophenol compounds, even in the low concentrations used in water conditioning, have been reported41 to produce dermatitis. Chromitch is not uncommon among workers handling chromates. The amines are said to be absorbed through the skin.42 Morpholine is said to cause kidney and lung trouble when so absorbed. Chlorine gas irritates the skin, eyes, and mucous membranes. Concen trations as low as 0.004 percent by volume in air cause dangerous illness in 0.5 to 1 hour. When relatively large amounts of the non-gaseous chemicals are to be handled, protective clothing, including goggles, should always be pro vided, and a shower head or its equivalent provided at or very near the point where the chemicals are mixed. Chemicals should always be washed from the skin with large volumes of water. For the handling of chlorine and chlorinators, the U. S. Public Health Servicea stipulates the following safety requirements: 1. Suitable gas masks and a smalt bottle of ammonia for testing for leaks should be kept at convenient points immediately outside the room or enclosure in which chlorine is being stored or is in use. Gas masks should be inspected at regular inter vals and kept in serviceable condition. Note:--All-purpose masks offer adequate protection only when the concentration of acid gases does not exceed two percent-- see Safe Practices Pamphlet #64 National Safety Council. 2. Chlorinating equipment and cylinders of chlorine should be housed preferably in separate buildings above the ground level. 3. The room or building housing chlorinators in service should be maintained at a temperature above 60 F, but never in excess of the normal summer temperature. The cylinders of chlorine should be shielded, where necessary, from excessive heat or cold. Direct heat should not be applied to cylinders of chlorine, nor should hot water be poured over them or come in contact with the cylinder valve. 4. Adequate ventilation should be provided for all enclosures in which chlorine is being fed or stored. 5. All joints of tubing connecting chlorine cylinder and chlorinators should be kept absolutely tight and inspected frequently to insure tightness. Tubing should slope upward from the cylinder. LEGAL REGULATIONS In a number of states, the water used for humidification, even in in dustrial plants, is required to meet drinking water standards insofar as bacteriological quality is concerned. A ruling of the JJ. S. Department of Agriculture, Meat Inspection Division, prohibits the use of chromate in water used for air washing when the air later contacts foodstuffs.44 There is an ever growing consciousness oh the part of public health officials, of the necessity for regulations to protect potable water supplies. Attesting this is an ordinance46 now in effect in Detroit, Michigan, which stipulates in part : Corrosion and Water Formed Deposits, Causes and Prevention 1003 "No physical connection shall loe maintained between lines carrying city water and pipes, pumps, or tanks supplied from any other source. Where dual supplies are necessary or desired, lines carrying city water must be protected against back flow of polluted water by an atmospheric gap. Secondary supplies and emergency sources shall include: surface waters from rivers, lakes, ponds, lagoons, and reser voirs; well waters both deep and shallow; any supply of water which has been stored i- reserved after being used for industrial purposes; cooling water, or water which has in any way been treated, processed, or has been subjected or exposed to any contamination of a bacteriological or chemical nature; and water from any other source than the city supply." The XJ. S. Public Health Service stipulates: "Salts of barium, hexavalent chromium, heavy metal glucosides, or other sub stances with deleterious physiological effects, shall not be allowed in the water supply system. The same agency recommends that the concentration of the substancea listed be held below the values cited in Table 8. The Board of Directors' Table 8. Recommended Maximum Allowable Content in Water Supply* Substance Max. Concen tration, ppm Substance Max. Concen tration, ppm Copper................................... Iron & Manganese (Total) . Magnesium...... Zinc.................. Lead............................ Fluorine.............................. 3.0 0.3 125 0 15 0 0.1 1.0 Selenium................ Phenols (Total)......... Poly-phosphate of Sodium. 0.05 0 05 o.ooi 10.0 10.6 a U. S. Public Health Service. of the American Water Works Association has accepted these values as standard for all public water supplies in the United States.46 While their action is not binding, prudence dictates that no form of treatment should be used that will result in raising the concentration of the substances listed above the value cited. Since virtually all of the permissible chemicals used for scale, slime, and corrosion control have deleterious, physiological effects if taken internally in relatively large doses, they should always be carefully proportioned. To msure this, the Detroit ordinance stipulates that the chemical feeding device must have the following major characteristics: "}. There shall be a visible means of checking the quantity of material being applied by the feeding device. 2. A water metering device, sealed to prevent tampering, shall be installed to measure the flow of water being treated. 3. The device shall be constructed so that in the event of back-flow or vacuums, tne maximum amount of material that may be possibly back-siphoned from the device or any of its attachments or parts shall not exceed one fluid ounce. 4- Should there be a failure of the water metering device or the water supply, me feeding device shall automatically cease operating.tf 1 Annual Report (1947) Committee D-I9 (American Society for Texting Material*). * Corrosion Handbook, edited by H. H. Uhlig (John Wiley & Sons, p. 27). * Discussion, Corrosion and Material Protection, May 1945, p. 2. fPrlfjnd TaAble on Organising the Classification of Industrial Waters, by W. C. Schroeder UToceedings, American Society for Testing Material*, VoL 44, 1944, p. 1057). * Typical Water Analyses for Classification with Reference to Industrial Use, by W. D. Collins (Proceed tng*, American Society for Testing Materialt, Vol. 44. 1944, p. 1057). cornua irroceeo