Document LJNbkV8MEGeMdYDLyvegbw0e7

964 CHAPTER SO 1049 Guide' and is insulated. <. Over the top of; the box glass ;sash are; placed and the box should be constructed as near air-tight as possible. . The interior sur faces should be painted white to reflect the heat, while the coil should be painted black to absorb the heat. The box need not be deeper than neces sary to house the coil and to protect it from the weather; ' The addition of a light gage copper plate on the :bottom of the box to which the pipe of the coil is soldered, for good metallic contact, will add to the amount of heat received by the coil due to the fact that this plate will receive all of the sun rays which fail to directly strike the coil; The heat from this source is transmitted to the coil through the plate instead of by heating the air surrounding the coil and from which only part of the heat enters the coily the balance being transmitted through the glass sash. Design data given in Table 8 may be used with some judgment in select ing the size of solar heater coil and box for a particular application. These data are based on consumptions of 30 and .40 gal of hot water per day per person. REFERENCES 1 Methods of Estimating Loads in Plumbing Systems, by R. B. Hunter (National Bureau of Standards, Report BMS65, 1940). Plumbing Manual, Report of the Sub committee on Plumbing, Central HousingCommittee on Research, Design and Con struction (National Bureau of Standards, Report BMS66,1940). Water-Distributing Systems for Buildings, by R. B. Hunter (National Bureau of Standards, Report BMS79,1941). * Water Distributing Systems for Buildings, by R: B. Hunter (National Bureau of Standards, Report BMS79, p. 6-9). (Charts extended to flow of 0.39 gpm.) * Plumbing Practice and Design, by Svend Plum (John Wiley and Sons, Inc., 1943). BIBLIOGRAPHY . Laundry, Kitchen and Hospital Equipment, by H. C. Russell (A.S.H.V.E. Trans actions, Vol. 35,1929, p. 45). Water Consumption, Cost and Savings, by G. C. St. Laurent (American Hotel Association, Hotel Engineering, Vol. 1,1940). Water-Supply Piping for the Plumbing System, by F. M. Dawson and A. A. Kalinsko (Technical Bulletin No. 3, National Association of Master Plumbers). Use of Solar Energy for Heating Water, by F. A. Brooks, Smithsonian Institution; Washington, D. C-. ' CHAPTER 51 CORROSION AND WATER FORMED DEPOSITS CAUSES AND PREVENTION Definitions, Classification and Characteristics of Water, Causes and Prevention of Scales and Sludges, Causes and Prevention of Slimes, Under-Water Corrosion, Atmospheric Corrosion, Buried Pipe Lines, Handling Water Treating Chemicals, Legal Regulations THE surfaces of heating and, ventilating equipment that are in in timate contact with water sometimes are affected by the chemical characteristics of. the contacting waters to such extent that prohibitive amounts of insoluble materials are formed or corrosion ensues at an in sufferable rate.. To avoid or to correct such troubles, it is desirable that heating and ventilating engineers have a general appreciation of industrial water chemistry. The principal purpose, of this chapter is to provide those criteria by. which the average engineer may. judge whether a problem is one that will yield to rather simple remedies or will require the skill of an experienced'water technologist. " DEFINITIONS The following definitions for water-formed deposits, corrosion, and closely allied terms have been proposed: Water-Formed Deposits. A water-formed deposit1 is any accumulation of insoluble material derived from water or formed by the reaction of water upon surfaces in contact with water. Deposits formed from or by water in all of its phases may be further classified as scale, sludge, corrosion products, or biological deposits. Scale. Scale1 is a deposit formed from sblutiondirectly in place upon a confining surface. It is a deposit which will retain its physical shape when mechanical means are used to remove it from the surface on which it is deposited. Scale, which may, or may. not adhere to the underlying surface, is usually crystalline and dense,fre,quently laminated, and occasionally columnar in structure. Sludge. Sludge1'is a water-formed sedimentary deposit. It usually does not cohere sufficiently to retain its physical shape when mechanical means are used to remove it from the surface upon which it deposits. Sludge is not always found at the place where it is formed. It may be hard and adherent and baked to the surface on which it has been deposited. Biological Deposits. Biological deposits1 are water-formed deposits of biological organisms or the products of their life processes. Biological deposits may be micro scopic in nature, such as slimes, or macroscopic, such as barnacles or mussels. Slimes are usually composed of deposits of a gelatinous or filamentous nature. - Corrosion. Corrosion* is destruction of a metal by chemical -or electrochemical reaction with its environment.. In the corrosion process* the reaction products formed may be soluble or insoluble in the contacting environment. Insoluble cor rosion products may deposit at or near the attacked area or be carried along and deposited at considerable distance from the attacked area. Corrosivity. Corrosivity* is the capacity of an environment to bring about de struction of a metal by the process of corrosion. Corrosivity is a property of the environment, but it has no significance until the metal in question is specified. 965