Document mpJ7pQ709xNMxL2prZwqd0REB

902 . . CHAPTER 51 ,, , 1948 Guide of the.water is a major factor. .It is therefore desirable to obtain an accur ate estimate of the minimum current:density required.: The.current is then controlled by the potential between the anode and the structure: to be prptected. . Rectifiers have generally proved tobethe most practical means for supplying:the necessary current for protection of surfaces in contact with neutral waters4. 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, li:me, and concentrated'sulphuric acid will burn the flesh. In addition, if mixed with small amounts of. water, sufficient heat may be generated so that spattering occurs or. the; container becbhies too hot to handle. The chlprophenol cornpounds, even in. the low concen trations used in water conditioning, have been reported3 to prod.uce.dermatitis! , Chrom- itch is not uncommon , among workers handling chromates. . The amines ate said to be absorbed through the skin:33. 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 per epntby yolume.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, should5 always'be jprovided. and a.shower.head or its.equivalentprovided,at, or. very near the point where the chemicals .are .mixed:; Chemicals should always, be washed from the shin with large volumes of waters , , ;s:...; For the handling: of.chlorine and chlorinators, the U. S. Public Health Service?7 stipulates the following safety, requirements: .: -4-j. . ,1. Suitable gas masks and a smalf bottle of ammonia for testing'for liiaks' should be kept at convenient points irnmediaitely outside the rdom'br hhybbure'iniwKich chlorine is being stored or isln use.; Gas'masks should be inspected at regular intervals and kept in serviceable-condition.. Note:--Alt purpose ma^ks offer:adequate. protection only when the concentration pf acid gases, does not exceed , jtwo per cent--See ."Safe-Practises Pamphlet #64 National'Safety Council". . ' ' 2. Chlorinating equipment and cylinders of chlorine should be housed preferably in separate buildings above the ground level. `-'-i-JO"'"" i1 3. The rpom. or budding housing chlorinators in service should be maintained at a temperature above 60 I'-, blit never in excess of the normal summer temperature: The c^clinders of chlorine' should be shietded,: where necessary; from excessive heat or cold. Direct.heat should not b.e applied to cylinders of chlorine nor should hot water be poured over them or come in contact with the:cylindeqyalve.. - ti! '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 tQ insure tightness. .Tubing should slope upward from the cylinder. ' LEGAL REGULATIONS : In a inumber of states, the water used for humidification, even in in dustrial, plants,'is. required to meet drinking water standards insofar as .bacteriological quality is.coricerned. A ruling, of the U. S. Department of Corrosion and Water Farmed Deposits Guides and Prevention 903 . Agriculture, Meat Inspection.pivi^qnjiJrohibits the use of chromate in water used for air washing when fhe ffirlader contacts foodstuffs38. : There is an'ever growing consciousness on the part' of public health officials of the necessity for. regulations to protect, potable water supplies. Attesting this is an ordinance33 now,in effect,in Detroit, Michigan, which stipulates in part: .... . ' . . "No physical connection shall be maintained between lines carrying city water and pipes, pumps, or tanks supplied from any-other source... Where dual supplies-are nec essary 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 reservoirs ;'well'waters both deep and shallow; any supply of'water which has been stored, held; or 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 ai bacteriological or chemical nature; and water-'from any other source than the city supply." : ' " The U. S. Public Health Service stipulates: . "Salts of barium/hexavalent chromium, heavy metal glupdrides, mr,other substances with deleterious physiological effects, shall not be allowed in the water supply system." The same agency recommends that the concentration of the substance hereinafter listed be held below .the values cited: , S. ... .Substance ...... Wax.,-: . .Concentration, /'p4)nr':, v Iron's Manganese {TotaDVj.J-L^.^i.^rr----ir-- 3:6 -: =' 0.3 ' ` . Magnesium................. ........................................---------........................- 125.0 ,v 15.0 ' 0.1 ` ' Fluorines______ -----.......... ,.-.--.,r-,.--........................ -.-.... ....- -- ------ . ......1.0 -. ............. 0.05 - ' K1.05 " * o.ooi" Poly-phosphate of Sodium----- pH Value ^ .... ........................................................ 10.0-1 10.6....... The Board of Directors of the American Water,.JAfpries, Association has accepted these values as standard for all .public water, supplies in the Uhited 'SiafesKi^-While theii^ctibn is ribt .bmdirig, firiiilMce dictates.that. no form of treatment should be used that will resultvin raising the con centration 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 carefullyproportioned. To insure this, the Detroit Ordinance stipulates that the chemical feeding device must have the following major-characteristics: ; "1. There shall be a visible means of checking, thequaptity 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, the 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, the feeding device shall automatically cease operating."