Refrigeration Manual - HVAC and Refrigeration Information Links

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OPEN TYPE COMPRESSORSEarly models of refrigeration compressors were of theso-called open type, with the pistons and cylinders sealedwithin a crankcase, and a crankshaft extending throughthe body for an external power source. A shaft sealaround the crankshaft prevented the loss of refrigerantand oil from the body.Although at one time open type compressors were widelyused, they have many inherent disadvantages such asgreater weight, higher cost, larger size, vulnerability toseal failures, difficult shaft alignment, excessive noise,and short life of belts or direct drive components. Asa result, the open type compressor has been largelyreplaced with the accessible-hermetic and hermetictype motor-compressor in most applications, and theuse of open type compressors continues to declineexcept for specialized applications such as automobileair conditioning.WELDED HERMETIC MOTOR-COMPRESSORSIn an effort to further decrease size and cost, the weldedhermetic motor-compressor has been developed, andis widely used in small horsepower unitary equipment.As in the case of the accessible-hermetic motorcompressoran electric motor is mounted directly on thecompressor crankshaft, but the body is a formed metalshell hermetically sealed by welding. No internal fieldrepairs can be performed on this type of compressorsince the only means of access is by cutting open thecompressor shell.ACCESSIBLE-HERMETIC MOTOR-COMPRESSORSThe accessible-hermetic motor-compressor design waspioneered by Emerson Climate Technologies, Inc. andis widely used in the popular Copelametic® models.The compressor is driven by an electric motor mounteddirectly on the compressor crankshaft, with both the motorand the compressor working parts hermetically sealedwithin a common enclosure. The troublesome shaft sealis eliminated, motors can be sized specifically for theload to be handled, and the resulting design is compact,economical, efficient, and basically maintenance free.Removable heads, stator covers, bottom plates, andhousing covers allow access for easy field repairs inthe event of compressor damage.COMPRESSOR SPEEDEarly models of compressors were designed for relativelyslow speed operation, well below 1,000 RPM. In orderto utilize standard 4 pole electric motors, accessiblehermeticand hermetic motor-compressors introducedoperation at 1,750 RPM (1,450 RPM on 50 cycle). Theincreasing demand for lighter weight and more compactair conditioning equipment has been instrumental in thedevelopment of hermetic motor-compressors equippedwith 2 pole motors operating at 3,500 RPM (2,900 RPMon 50 cycle).Specialized applications such as aircraft, automotive, ormilitary air conditioning equipment utilize even higherspeed compressors, but for the normal commercialand domestic application, the existing 60 cycle electricpower supply will generally limit compressor speeds tothe presently available 1,750 and 3,500 RPM.Higher compressor speeds introduce lubrication andlife problems, and these factors as well as cost, sizeand weight must be considered in compressor designand application.(continued on p. 4-4)© 1967 Emerson Climate Technologies, Inc.All rights reserved.4-2
CROSS-SECTIONAL VIEW OF COPELAMETIC® MOTOR-COMPRESSOR4-3© 1967 Emerson Climate Technologies, Inc.All rights reserved.
Page 3 and 4: Part IIREFRIGERATION SYSTEM COMPONE
Page 5: Section 4COMPRESSORSThe compressor
Page 9 and 10: When the piston starts down on the
Page 11 and 12: COMPRESSORS WITH UNLOADERSIn order
Page 13 and 14: flow by means of louvers is also an
Page 15 and 16: Figure No.20 shows parallel circuit
Page 17 and 18: and the total pressure existing in
Page 19 and 20: if the evaporator temperature is to
Page 21 and 22: In modern refrigeration practice, a
Page 23 and 24: CAPILLARY TUBE SELECTION R-22HIGH T
Page 25 and 26: CAPILLARY TUBE SELECTION R-12MEDIUM
Page 27 and 28: CAPILLARY TUBE SELECTION R-502LOW T
Page 29 and 30: multiple evaporators are used. On l
Page 31 and 32: which may be caused by pulsations i
Page 33 and 34: WATER REGULATING VALVESOn water coo
Page 35 and 36: CONDENSER FAN CYCLING CONTROLIn ord
Page 37 and 38: 1. The continuous VA (volt-amperes)
Page 39 and 40: A. Continuous VA requirement2 Conta
Page 41 and 42: The desired pulley size or the resu
Page 43 and 44: un winding is wound with relatively
Page 45 and 46: TWO PHASE MOTORSTwo phase power is
Page 47 and 48: 1 = 1 + 1MFD total MFD1 MFD2For exa
Page 49 and 50: voltage torque, and star-delta star
Page 51 and 52: 10-6© 1967 Emerson Climate Technol
Page 53 and 54: Regular Copeland® brand motor prot
Page 55 and 56: contact prematurely due to shock or
Page 57 and 58:
The effect of an open phase in the
Page 59 and 60:
vulnerable to liquid damage such as
Page 61 and 62:
REFRIGERATION GAUGESPressure gauges
Page 63 and 64:
© 1967 Emerson Climate Technologie
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