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774 CHAPTER 48 Driers and Moisture Indicators Hie characteristics of refrigeration driers are discussed in Chapter 49. However, it is in order here to point out that aside from care in the manufacture of the equipment, the use of re frigerant driers is the main method used to combat the effects of contaminants in a refrigerant system. In the past the refrigeration serviceman had no way of knowing whether the system was dry enough. Even after changing the drier, tiie moisture level might still-be suffi ciently high to cause corrosion. This problem has been simpli fied with the introduction of moisture indicators. These.devices utilise a moisture sensitive paper which changes color ac cording to the moisture content of the refrigerant.47 By using this device the moisture level in the system can be easily checked. The color change in the moisture indicator normally takes place at a moisture level that is low enough to be con sidered safe. Manufacturers' instructions should be followed carefully, because in addition to the moisture concentration the color change point is also affected by the liquid line temperature and the particular refrigerant used. REFERENCES 1 A. H. Bushey: ASRE research task force reports on contamir cants (Refrigerating Encineebinq, February 1957, p. 47). 1 EL W. McGovern: Copper plating in refrigerating compressors (Service News, Septenber 1938. Issued by E. L duPont deNe- mours A Co., Inc.). I E. W. McGovern: Chemical effects in refrigerating systems (Refrigerating Engineering, May 1942, p. 276). - 4 EL Steinle and W. Seonan: The cause of copper plating in refrigerating machines (Kdltetechnik, 6, No. 4, 1953, p. 90). See also BL Steinleand W. Seeman (Ksltetedinik, S, No. 8,1951, p. 194). * H. Steinle: Tests on copper plating in refrigerating 'machines (Kdltetechnik, 7, No. 4, 1955, d. 101). 4 D. E. Rvalues and H. M. Parmelee: Behavior of Freon-12 and Freon-22 in sealed-tube tests (Refrigerating Engineering, November 1957, p. 40). , ... , 7 R T. Divers: Better standards are needed for refrigeration lubricants (Refrigerating Engineering, October. 1958, p. 40). * H. 0. Spauschus: Copper transfer in refrigerant-oil solutions (ASHRAE Journal, June 1963, p. 89). * H. M. Ebey, L. C. Flowers and J. B. Kelley: A method, of evaluating refrigerator oils (Refrigerating Engineering, July 1952, p.737). 10 F. J. Norton: Rates of thermal decomposition of CHClFi and CF|C1. (Refrigerating Engineering, September 1957, p. 33). u D. D. Wile: Non-condensibles: power kiters; refrigerant wastrels (Industrial Refrigeration, January 1959, p. 12). a H. O. Spauschus et ol: Material stabilities in vapor com pression refrigeration systems (XI International Congress`.of Refrigeration, Munich, Germany, September 3, 1963). " H. O. Spauschus and R. S. Olsen: Gas analysts--a new tool for determining the chemical stability of hermetic systems (Re frigerating Engineering, February 1959, p. 25). .? M F. G. Peck: Alcohol in refrigerating systems (Refrigerating Engineering, December 1956, p. 67). u H. Heckmatt: Separation of mineral lubricating oD from Freon-12 in refrigerators (Proceedings of the X International Con gress of Refrigeration, Vol. II, p. 64). u W. C. rerrival: Quantitative determination of fluorinated hydrocarbons by gas chromatography (Analytical Chemistry, January 1957. p. 20). 17 Quality Specifications and Methods of Analysis for the `Freon' Fluorinated Hydrocarbon Refrigerants- (Technical Bulletin B-8 Freon Products Division, E. 1. duPont deNemours A Co., Inc.): II A. W. Diniak, & EL Hughes and M. Fujii: Determination of water content in "Freon-12" circulating'iit a refrigeration system (Refrigerating Engineering, February 1954, p. 56). 11 W. R. Brisken: Moisture migration m hermetic refrigeration systems (Refrigerating Enginebbtnq, July 1955, p. 42). * W. A. Pennington: Refrigerant sampling (Refrigerating Enoinebbing, March 1950. p. 261). "EM. Parmelee: Solubility of air in "Freon-12" and "Freoi 22" (Refbigeratino Engineering, July 1951, p. 573). .. 1965 Guide And Data Boole ** B. J. Eiseman, Jr.: Effect of elastomers of "Freon" and other hatocarbons (Refrigerating Engineering, December 1949 d 1171). ** L. A. Philipp and B. E. Tiffany: Thermodynamics of sulfur dioxide oil systems (Refrigerating Engineering, May 1934. p- 248). ^ u V. A. WQliamitis: How chemical stability assures long atten tion-free performance of sealed refrigeration systems (General Motors Engineering Journal, S, No. 1, 1955, p. 22). a Handling "Freon" Fluorinated Hycrocarbon Compounds *n (fa Laboratory (Kinetic Technical Bulletin 14, Freon Products Di vision. E. I. duPont deNemours A Co., Inc., 1953 and 1955). * H. O. Spauschus and G. C. Doderer: Reaction of refrigerant 12 with petroleum oils (ASHRAEJournal, February 1961, p. 65). 17 H. M. Ebey and L. C. Flowers: The reaction between eleo- trical insulating paper and monochkirodifluoromethane (Re- frigebating Engineering, April 1956, p. 31). ** J. J. Lingane: Automatic coulometnc titration with electro- lytically generated silver ion: determination of chloride, bromide and iodide ion (Analytical Chemistry, April 1954, p. 622). " J. L. Mason, G. R. Whitnah, and E. M. Larson: The Study of Vapor-Cycle Refrigerants for High Performance Aircraft (Wright Air Development Center Technical Report 59-93, Actio Document No. AD151008, PB-131761, February 1958). " B. J. Eiseman, Jr.: Reactions of chloroQuoro-hydrocarbons with metals (ASHRAE Journal, May 1963, p. 63). ** Properties and Application of the "Freon" Fluorinated Hy drocarbons (Technical Bulletin B-2, Freon Products Division. E. I. duPont deNemours A Co., Inc., 1959). n R. E. Kirk and D. F. Othmer: Encyclopedia of Chemical Tech nology (VoL 1, Interscience Publishers, Inc., New York, 1947).' Corrosion and Its Prevention (Air Conditioning and Re frigeration Institute, 1958, p. 20). - ** H. Steinle: Chemical reactions between refrigerants and oils in refrigerating machines (Kdlletechnikt, No. 7.1950, p. 174). ** H. Steinle: Development and testing of lubricants for re frigerating machines (Presented at ASHRAE Semi-annual Meet ing, Januanr 27-29, 1964, New Orleans, La.). * W. O. Walker, S. Rosen, and S. L. Levy: Stability of mixtures of refrigerants and refrigerating oils (ASHRAE Joubnal August, 1962, p. 59). . 17 C. J. Rizzuti, G. D. Staffin, and A. W. Jenkins: Effects of additives and oil refining on refrigerant-refrigerator oil stability (ASHRAE Joubnal, July 1962, p. 31). **A. F. Brewer: Good compressor performance demands the right lubricating oil (Refrigerating Engineering, October 1951, p. 965). ** R. T. Divers and Walter West: Hermetic compressors in modern applications (ASHRAE Journal, April 1964, p. 55). H. Steinle: Examinations of the behavior of plastics in her metic units (XI International Congress of Refrigeration, Munich, Germany, September 3, 1964). 41 J. P. Harrington and R. J. Ward: Polyester film insulation for hermetic motors (ASHRAE Joubnal, April 1959, p. 75). * W. McMahon, H. A. Birdsall, G. R. Johnson and C. T. Camilli (Chemical and Engineering Data, January 1959, p. 57). " C. J. Bushouse: Degradation of polyester him by alcohols (ASHRAE JouBNAL^September 1961, p. 61). ** R. T. Divers: Electrical insulation and hermetic motors (Refrigerating Engineering, August 1957, p. 33).. * i?. A. Beacham and R T. Divers: Some practical aspects of the dielectric properties of refrigerants (Refrigerating Engi neering, July 1955, p. 33). *B. J. Eiseman, Jr.: How electrical properties of "Freon" compounds affect hermetic system's insulation (Refrigerating Engineering, April 1955. p. 61). 47 A. B. Guise and W. O. Krause: A simple moisture indicating device for refrigerating systems (Refrigerating Engineering, December 1957, p. 39). BIBUOGRAPHY J. P. Hurtgen and A. R. Mounce: New insulationsystem for hermetic refrigeration motors (ASHRAE Joubnal, July 1959; p. 60). H. M. Elsey, J. B. Kellej content of certain dried I compressors (ASHRAE Transactions, vol. 5, 1959, p. K W. O. Walker, S. Rosen, and 8. L. Levy: A Study ofthe factors influencing the stability of mixtures of refrigerant-22 and re frigerating oils (ASHRAE Transactions, Vol. 66, I960, p. 445). W. O. Krause, A. B. Guise, and E. A. Beacham: Time factors in the removal of moisture from refrigerating systems with desiccant type driers (ASHRAE Transactions, Vol. 66, 1960, p. 465). CHAPTER 49 MOISTURE IN REFRIGERANT SYSTEMS Sources and Effects; Drying Methods,-' Moisture Measurement; Desiccants, Adsorption and Chemical Reactions of Desiccants,Driers, Selecting A Drier, Testing and Rating THE AMOUNT of moisture in a refrigerantsystem must be kept below an allowable maximum in order .to provide 4. Copper plating.- 5. Chemical damage to msulation or other system materials. satisfactory operation: Therefore, it is imperative that mois ' IcO - separates from fluorinated hydrocarbons,'- methyl ture be removed from refrigerant system components during fchloride, methylene chloride; butane, 'and isobutane: when manufacture and assembly, and that precautions be taken to ever the amount of moisture is sufficiently great and the tem- guard against entry of moisture into the system during instal perature of the' refrigerant low enough. The low refrigerant lation or service operations. Furthermore, any moisture which temperature Causes formation of ice in expansion valves, enters the refrigerant system should be removed as rapidly as capillary tubes, and evaporators.- In low-temperature units a practicable; plugged expansion valve or capillary tube may result due to SOURCES OF MOISTURE the separation of wax from oil-refrigerant mixtures.1 The pres ence of wax may be demonstrated by washing the expansion Moisture may be present in a refrigerant system as a result of: . ` . .. '' 1. Faulty drying of equipment at factory and,.in service operations. *.*__ 2. Introduction during installation or service operations in the field. -. -. 3. Low.-side leaks,- resulting in entrance of moisture-laden air. 4. Leakage of water-coolea condenser. \ 5. Oxidation of certian hydrocarbons of ofl to produce moisture. 6. Wet oil, refrigerant, or botlx 7. Decomposition of motor insulation in-hermetically-sealed units. . -. ` valve with a small amount Of carbon tetrachloride, and evapo rating the solution'so obtained. The presence of white wax or an extremely viscous oil-wax mixture proves that wax is the cause of'trouble'although-this does'not rule out-moisture; The wax separation characteristics (see section on Floe Testa in Chapter 50) of the oil should be determined,1 and if they are not satisfactory, another oil should be used; The separation of water as ice is-'related-to' the solubility of water in a refrigerant-The solubility of water varies with the different'refrigerants mentioned and is great enough-in ammonia,'carbon'dioxide,'-and sulfur dioxide so that freezing The drying .of,,equipment in the manufacturer's' plant is discussed in Chapter 47. / -` ' Proper installation and service procedures will eliminate does not occur. The-greater the solubility of water in a re1 frigerant, the less likely is it that ice will separate. The curves of Fig. 1 show the solubility of water in certain halogensted the sources listed in items 2/3 and 4. The subject of moisture in refrigerants is discussed'in Chapter 19. Lubricants aradiscussed in CHapter 50.'If refrigerants and oils are purchased id meet specifications, .and properly handled after receipt/rfche moisture'content generally will be low enough'to avoid Hifficulty. Oils to be used, forTow-temperature systems may be further dehydrated;-See the sections'on Hermetic Motor hydrocarbons.* No data are available for butane and iso^ butane. ' Studies1*4 have shown that iron, aluminum;* and-copper corrode quickly in the presence of liquid water, and fluoro1 carbon refrigerants. Water dissolved in-these refrigerants corrodes slowly even when its concentrations approach the individual saturation' points. Insulation and Motor Burnouts in Chapter 48. ' The mechanism of corrosion, which results in the formation of metallic, salts (sludges) has been studied.1 Water reacts with EFFECTS ,OF MOISTURE - The presence of moisture in a,refrigerating system may re* suit in one or all of the following undesirable effects:.-. sulfur dioxide, methyl chloride and Refrigerants 11,-' 12, 21, 22, 113, and 114 (hydrolysis1*1) whensufficient moisture is present,' to form sulfurous, hydrochloric, and hydrofluoric acids. These acids react with iron, copper; and aluminum to 1. Freezing at expansion valves or capillary tubes,-or formauon Mice in evaporators.- J. 2. Corrosion of metals to form sludge. 3. Flapper valve failure. form metallic "salts: (sludges) of well defined' composition. Hydrolysis accounts for'only,a little acid.-The greater.portion is derived from direct action of the refrigerant and oil at higher than normal operating temperatures.7'1 By chemical Tba ceaml wqwaaibgh/ (or Ibis chapter to to TC 1.11, 8arptto. analysis* of salts, it is possible to demonstrate their 773 ^