Manual for Refrigeration Servicing Technicians - UNEP - Division of ...

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3 Refrigerant Management CHAPITRE 3 PAGE 11 Vapour recovery mode Vapour transfer The refrigerant charge can be recovered in vapour recovery mode as shown in this diagram. DISABLED UNIT Vapour recovery mode Vapor Side Liquid Vapor SCALE Drier Vapor Liquid Recovery Cylinder RECOVERY UNIT On larger refrigeration systems this will take appreciably longer than if liquid is transferred. The connection hoses between recovery units, systems and recovery cylinders should be kept as short as possible and with as large a diameter as practicable. Liquid transfer Until recently, it was unheard of to recover direct liquid. But with the use of oil-less compressors and constant pressure regulator valves, it’s become the preferred method of recovery by most recovery Inlet Outlet equipment manufacturers. Oil-less recovery equipment has an internal device to flash off the refrigerant. Oil-less compressors will tolerate liquid only if metered through a device like a CPR (crankcase pressure regulating) valve. Don’t attempt to use the liquid recovery method unless your unit is designed to recover liquid. Liquid recovery is performed the same way as standard vapour recovery. The only difference is that you will connect to the high side of the system. Recovering liquid is ideal for recovering large amounts of refrigerant. If the recovery unit does not have a built-in liquid pump or is otherwise not designed to handle liquid, then liquid can be removed from a system using two recovery cylinders and a recovery unit. The recovery cylinders must have two ports and two valves, one each for liquid and one each for vapour connections. Connect one cylinder liquid port directly to the refrigeration system at a point where liquid refrigerant can be decanted. Connect the same cylinder vapour port to the recovery unit inlet. Use the recovery unit to draw vapour from the cylinder, thereby reducing the cylinder pressure, which will cause liquid to flow from the refrigeration system in to the cylinder. Take care as this can happen quite quickly. The second cylinder is used to collect the refrigerant from the recovery unit as it draws it from the first cylinder. If the recovery unit has adequate onboard storage capacity this may not be necessary. Once the entire liquid refrigerant has been recovered from the refrigeration system, the connections can be relocated and the remaining refrigerant recovered in vapour recovery mode. 70
3 Refrigerant Management CHAPITRE 3 PAGE 12 Liquid recovery using a vapour only recovery machine It may be and found two convenient recovery cylinders to fit a liquid sight glass within the transfer line. Do not connect the liquid line to the transfer unit compressor otherwise it will be damaged. The set-up of this scheme is illustrated here: refrigeration system st 1 recovery cylinder vapour-only recovery machine nd 2 recovery cylinder Liquid recovery using a vapour only recovery machine and two recovery cylinders Push and pull liquid recovery There is another method for liquid recovery; more common than that described previously, called the “push and pull” method. If you have access to a recovery cylinder, the procedure will be successful CHAPITRE 3 if you connect the recovery cylinder to the recovery units vapour valve, and the recovery cylinder liquid valve to the liquid side on the PAGE 13 disabled unit as shown in the diagram. The recovery unit will pull the liquid refrigerant from the disabled unit when decreasing the Push and pull recovery method pressure in the recovery cylinder. Vapour pulled from the recovery cylinder by the recovery unit will than be pushed back to the disabled unit’s vapour side. DISABLED UNIT Vapor Side Liquid Side Sight Glass Push and pull recovery method SCALE Drier Vapor Liquid 71 Inlet Recovery Cylinder Outlet RECOVERY UNIT
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Manual for Refrigeration Servicing
Page 3 and 4:
Introduction When to use the manual
Page 5 and 6:
Introduction The Factors affecting
Page 7 and 8:
Introduction How to assess conditio
Page 9 and 10:
Introduction Characteristics of Sel
Page 11 and 12:
Introduction Another form of refere
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Introduction Choose your chapter Th
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1 Environmental impact of refrigera
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1 Environmental Impact The ozone la
Page 19 and 20: 1 Environmental Impact RADIATION FR
Page 21 and 22: 1 Environmental Impact The ozone la
Page 23 and 24: 1 Environmental Impact Effects of o
Page 25 and 26: 1 Environmental Impact The greenhou
Page 27 and 28: 1 Environmental Impact Timeline act
Page 29 and 30: 1 Environmental Impact Alternative
Page 31 and 32: 1 Environmental Impact The way forw
Page 33 and 34: 2 Refrigerants 2.1. Section objecti
Page 35 and 36: 2 Refrigerants Chemical properties
Page 37 and 38: 2 Refrigerants Safety characteristi
Page 39 and 40: 2 Refrigerants Types of refrigerant
Page 41 and 42: 2 Refrigerants Those with ozone dep
Page 43 and 44: 2 Refrigerants Those with zero ozon
Page 45 and 46: 2 Refrigerants Carbon dioxide (CO2,
Page 47 and 48: 2 Refrigerants Azeotropic Blends An
Page 49 and 50: 2 Refrigerants Using Refrigerant Bl
Page 51 and 52: 2 Refrigerants Lubricants Today, al
Page 53 and 54: 2 Refrigerants Refrigerants and app
Page 55 and 56: 2 Refrigerants Properties of most c
Page 57 and 58: 3 Refrigerants Content Management M
Page 59 and 60: 3 Refrigerant Management The majori
Page 61 and 62: 3 Refrigerant Management Handling o
Page 63 and 64: 3 Refrigerant Management Recovery c
Page 65 and 66: 3 Refrigerant Management Refrigeran
Page 67 and 68: 3 Refrigerant Management Refrigeran
Page 69: 3 Refrigerant Management Open Refri
Page 73 and 74: 3 Refrigerant Management Recycling
Page 75 and 76: 3 Refrigerant Management equipment
Page 77 and 78: 3 Refrigerant Management CHAPITRE 3
Page 79 and 80: 3 Refrigerant Management PAGE 22 Ex
Page 81 and 82: 3 Refrigerant Management CHAPITRE 3
Page 83 and 84: 3 Refrigerant Management Further re
Page 85 and 86: Summary This section will provide t
Page 87 and 88: 4 Servicing Practices Moisture Mois
Page 89 and 90: 4 Servicing Practices Non-condensab
Page 91 and 92: 4 Servicing Practices Evacuation A
Page 93 and 94: 4 Servicing Practices 7 - For large
Page 95 and 96: 4 Servicing Practices Pressure unit
Page 97 and 98: CHAPITRE 4 4PAGE 10 LEAK DETECTION
Page 99 and 100: 4 Servicing Practices Detection met
Page 101 and 102: 4 Servicing Practices CHAPITRE 4 PA
Page 103 and 104: 4 Servicing Practices Volumetric ch
Page 105 and 106: 4 Servicing Practices Electronic ch
Page 107 and 108: 4 Servicing Practices Why charge re
Page 109 and 110: 5 Retrofitting Content General retr
Page 111 and 112: 5 Retrofitting • Upon evaluation
Page 113 and 114: 5 Retrofitting General retrofitting
Page 115 and 116: 5 Retrofitting procedures that you
Page 117 and 118: 5 Retrofitting MVAC retrofitting pr
Page 119 and 120: 5 Retrofitting Although, in general
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5 Retrofitting Further reading UNEP
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6 Summary 6.1. Overview of refriger
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6 Safe Refrigerant Handling Oxygen
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6 Safe Refrigerant Handling The com
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6 Safe Refrigerant Handling • Nev
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6 Safe Refrigerant Handling Safe ha
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6 Safe Refrigerant Handling leak de
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6 Safe Refrigerant Handling • Lea
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6 Safe Refrigerant Handling Storage
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6 Safe Refrigerant Handling Recomme
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6 Safe Refrigerant Handling 3 - Sho
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Glossary Glossary Absolute pressure
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Glossary Fossil fuels Carbon-based
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Glossary hole in late 1985, governm
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Glossary Sealed system A refrigerat
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Acknowledgements Acknowledgements I
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Copyright Copyright © United Natio
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