Good Guide - Refrigeration & Heating

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Guideto

Good

Commercial

RefrigerationPractice

Part8

RefrigerantsandRetrofitting

BritishRefrigeration

Association

InstituteofRefrigeration

Issue1December2008


3/13

GuidetoGoodCommercialRefrigerationPracticePart8


BritishRefrigerationAssociation InstituteOfRefrigeration

2

CONTENTS

8.1.0

INTRODUCTION

8.2.0 REGUALTORYCONSIDERATIONS

8.2.1 GENERAL

8.2.2 OZONEDEPLETION

8.2.3 GLOBALWARMING

8.3.0 REFRIGERANTTYPES

8.3.1 GENERAL

8.3.2 HALOCARBONS

8.3.3CFCs

AND

HCFCs

8.3.4 HFCs

8.3.5 HYDROCARBONS

8.3.6 AMMONIA,R717

8.3.7 CARBONDIOXIDE,R744

8.4.0 REFRIGERANTSELECTION

8.4.1 ENERGYEFFICIENCY

8.4.2 NEWINSTALLATIONS

8.4.3 CONVERSIONOFEXISTING(ODSCONTAINING)SYSTEMS

8.4.4

COMPRESSOR

LUBRICATING

OIL

CONSIDERATIONS

8.5.0 REFRIGERANTSCOMMERCIALLYAVAILABLE

8.6.0 LEAKDETECTION


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3

8.1 INTRODUCTION

Refrigerant isoneof thekeycomponents ina refrigerationsystemandshouldbe

selectedwithgreatcarebecause itschoicecanimpact,substantially,onthesystem

design,andancillarymechanicalcomponents.Therefrigerantshouldbeselectedto

ensurethat

the

system

will

be

cost

effective

(throughout

the

lifetime

operation

of

thesystemandshouldnothaveanydetrimentalenvironmentaleffects)consistent

withuseandlocalregulatoryrequirements.

8.2 REGULATORYCONSIDERATIONS

8.2.1 GENERAL

Refrigerantsarevolatilechemicalsubstances theyexist in the liquidphasewhen

containedunderpressure,butmostrefrigerantswillbe inthevapourphaseunder

atmospherictemperatures

and

pressures.

If

the

refrigerant

is

released

due

to

an

accidentalruptureof thesystemorasa leak,refrigerantvaporisesrapidlyandwill

quickly diffuse into the local atmosphere before eventually dispersing. Local

concentrations in air can exist for long periods before dispersing (by means of

convection, natural airmovement,mechanical ventilation, or othermechanisms).

Refrigerant/airmixtureshavesignificantsafetyconsequencesforhumans, including

thepotentialforasphyxia,toxiceffects(frominhalationofrefrigerantvapours)and,

inthecaseofflammablerefrigerants,fireorexplosion. Chemicallyinertrefrigerants

existintheatmosphereformanyyearswithpotentialadverseconsequencesforthe

globalenvironment.

Use of refrigerants is controlled through safety regulations by regulatory bodies.

Regulations are based on the safety classification of refrigerants, which govern

applicationsandlocationsofuse.Theregulationsusesafetystandardsastheirbasis.

EN378:2008assignssafetyclassificationsandPracticalLimitconcentrationsforeach

refrigerant. These classifications and Practical Limits govern themaximum system

chargesizeforspecifiedOccupancycategories.

In general the morestrict the safety class of the refrigerant (by toxicity or

flammability class, or both) the smaller the system charge allowed by the

regulations,especially

where

the

public

may

be

affected

in

the

case

of

abnormal

operation. Systemsaredesignedwherehighly toxicor flammable refrigerantsare

usedwithacceptablehazardrisk,howeversuchdesignsarecomplexwithadditional

costs.

8.2.2 OZONEDEPLETION

Environmental regulations have a significant impact on the refrigeration industry.

The introduction of the Montreal Protocol bans the use of Ozone Depleting

Substances(ODSs).

ThisProtocol

was

enacted

in

Europe

as

Regulation

2037/2000,

(See

Part

3)

which

banned the use of CFC refrigerants ( R11, R12, R502 and others) both for new


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4

systemsand forservicingexisting systemsandHCFC refrigerants (ofwhichR22 is

thebestknown) foruseinnewsystems. Newlyproduced(socalledvirgin)HCFC

refrigerants can be used for servicing existing refrigeration and airconditioning

systemsonlyuntil theendof2009.RecoveredHCFCrefrigerantscanbeuseduntil

theendof2014.

8.2.3 GLOBALWARMING.

Manyfluorinatedrefrigerantsaregreenhousegases(GHGs)whichwhenreleasedto

theatmospherecontributetoclimatechange(commonlyknownasglobalwarming).

AlthoughpotentGHGs intermsoftheir individualGWPs, HFCrefrigerantswhich

arereplacingtheOzonedepletingCFCandHCFCrefrigerantsarecurrentlyreleased

in smallquantities incomparisonwithotherGHGs (CO2,Methane,NitrousOxide,

etc.)thattheiroveralleffecton climateissmall.Itisimportant,howevertoensure

that theemissionsofHFCsarenotallowedtogrow inanuncontrolledmanner.To

thisend

the

EU

has

introduced

the

FGas

Regulation

(See

Part

3)

aimed

at

controlling

emissions of nonODS Fluorinated fluids, (HFCs and PFCs). The use of these

substancesisnotpermittedinmanynonrefrigerationapplications.Theyareallowed

in refrigeration and air conditioning systems subject to controls ensuringminimal

emissions.

8.3 REFRIGERANTTYPES

8.3.1 GENERAL.

Vapourcompression

cycle

refrigerants

are

those

which

change

their

physical

state

from liquid to vapour and back again, during the refrigeration cycle. The phase

change is used to collect heat from the evaporator and transfer heat to the

condenser.Refrigerantswhichchangetheirphaseattherequiredtemperatureonly

existasvapoursatnormalambientpressuresandtemperatures,andhencetheiruse

in a closed circuit system inwhich the refrigerant is contained during itsworking

lifetime. Refrigerants must be inert (unreactive) to the component parts of the

system. Thereareseveralgroupsofchemicals,whichmeettheserequirements.

Themainclassesofrefrigerantfluidsare:

HalogenatedFluids,ieHCFCsandHFCs

Hydrocarbons

Ammonia

Carbondioxide

8.3.2 HALOCARBONS

These synthetic chemicals have been used for domestic, commercial and many

industrial refrigerationandairconditioning systems since their introduction in the

early1930s,

due

to

their

chemical

inertness

and

low

hazard

to

humans.

The

halocarbon family of refrigerants are often used as mixtures of two or more


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5

individual refrigerants to produce a blend with appropriate physical properties

(principallyboilingpoint)fordifferentrefrigerationapplications.Toaididentification

of these substances an R Number classification system has been universally

adoptedbytherefrigerationindustry.AllrefrigerantshavebeenassignedauniqueR

Number.(Theserefrigerantsaresubjecttospecificregulations intheUKSeeclause

8.2.2)

8.3.3 CFCSsANDHCFCs

Asubsetof thehalocarbon family isthechlorinecontaininghalocarbons (CFCand

HCFC refrigerants ), and bromine containing halocarbons (Halons), which are

responsible for StratosphericOzoneDepletion and arebeing phasedoutunder

regulationsinaccordancewiththeMontrealProtocol(see8.2.2).

8.3.4 HFCs

Nonchlorine (or bromine) containing halocarbons, the HFCs (and PFCs), are

replacingCFCsandHCFCs inmanyapplications.TheHFC/PFC familyhas far fewer

members than theoverallhalocarbon familyand relatively fewof thesechemicals

havetherequisiteproperties (physicalandsafety)toqualifythem forrefrigeration

use. Commercial refrigerants with the required properties have been developed

usingmixtures/blends(2,3,orsometimes4constituents)ofHFCs. Mixtures/blends

areassignedRNumbers,intheR400andR500series.

Blends are susceptible (to a greater or lesser extent) to a phenomenon called

compositionshift.

Composition

shift

is

aconsequence

of

adifference

in

composition

between the liquid and equilibrium vapour phases of the individual refrigerants

making up the blend. If, forexample the vapourphase leaks,or ispreferentially

removed, the remaining blend composition will be different from that of the

standard blend composition originally charged into the system. If a significant

quantityofvapourisremovedthecompositionoftheresidualliquid(andtherefore

itscharacteristicsasarefrigerant)canalsochange.

The composition of some blends (notably R407C) results in the blend not

evaporating/condensingata fixed temperatureandevaporates/condensesovera

rangeand

this

is

known

as

Temperature

Glide

In

practice,

for

commercial

refrigerantblendstemperatureglide isnotan issuetheevaporatororcondenser

behavesasifitstemperatureisatthemeantemperature.

WhileHFC refrigerantsused in commercialapplicationshaveattractive safetyand

physicalpropertiestheyareGreenHouseGases (GHG)andare included inClimate

Changeregulatorymeasures(see8.2.3above).

8.3.5 HYDROCARBONS.

Hydrocarbonrefrigerants

have

zero

ODP

and

very

low

GWP

and

as

aresult

of

their

environmentalpropertiestheyhavebeenintroducedasrefrigerantsinsmallsystems


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6

where the refrigerant charge is low. These refrigerants are highly flammable,

formingexplosivemixturesinair,andtheiruseisregulatedbysafetystandards(EN

378,EN60335240andothers)andlocalsafetyregulations.

Hydrocarbon refrigerants in properly designed systems are good refrigerants,

howevertheir

application

range

is

limited

because

of

their

safety

characteristics.

Butane (R600), iButane (R600a),Propane (R290) and Propene (R1270) are the

mostcommonlyusedrefrigerants

8.3.6 AMMONIA,R717

Ammonia(R717)isoneoftheoriginalchemicalsubstancesusedasarefrigerantfor

mechanicalrefrigerationsystems. IthaszeroODPandzeroGWP,but ithasahigh

levelof toxicity.Ammonia isused in large industrial refrigeration systems such as

cold stores. Safety regulations often prohibit the use of ammonia in refrigeration

systemsin

residential

areas.

Ammonia isalsoused (invery smallquantities) inabsorption refrigeratorsoften

seeninhotelroomminibars.

8.3.7 CARBONDIOXIDE,R744

CO2hasazeroODPandaGWP=1. Interestincarbondioxideisreawakeningdueto

its environmental properties and its attractive thermal transport properties (good

heattransferproperties).CO2doeshave,however,somechallengingpropertiesasa

refrigerant, suchasathighcondensingpressures (>100bar) Ithasa relatively low

criticaltemperature

(31C).

This

means

that

for

most

systems

the

high

pressure

vapourcannotbecondensedand this typeofsystem isdescribedas transcritical,

Veryhighgaspressures(>100bar) intranscriticaloperationaregeneratedandthe

gas iscooled inagascooler.CO2alsohasarelativelyhightriplepointpressure,5.3

bar,belowwhichaliquidphasedoesnotexist.

ConsiderabledevelopmentworkhasbeencarriedoutinrecentyearsonCO2systems

foruseincommercialapplications.

8.4 REFRIGERANTSELECTION

8.4.1 ENERGYEFFICIENCY

Refrigeration and air conditioning systems, collectively, are responsible for a

substantialproportionofglobalenergyconsumption.With the increasing focuson

ClimateChange,theenergyefficiencyofrefrigerationandACsystemsarebecoming

evermoreimportant.

Efficiency of refrigeration systems is governed by the laws of physics and by

practicality. Practicality embraces cost and legislative requirements, refrigerant

safetycharacteristics

and

maintenance

considerations.

Efficiency

is

primarily

dependent on good design, selection of appropriate system, good maintenance.


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7

Practicality often leads to a choice of HFC refrigerants. For some applications,

ammonia,hydrocarbonsorcarbondioxidewouldbethepreferredchoice,butthese

refrigerantsarenot suitable forallapplications. Gooddesignandmaintenance is

vitaltominimizeemissionsofgreenhousegases.

8.4.2NEW

INSTALLATIONS

Choiceofrefrigerantwillbedeterminedbytheapplication,system location,safety

andcosteffectivenessofsystemdesign. Systemdesign is typicallyevaluatedona

life cycle cost basis as to both the environmental cost in terms of total carbon

equivalentemissions,andtotalmonetarycostofownership(investment,operating,

maintenanceanddecommissioningattheendofitsusefullife).

Thereareregulatoryconstraintsontheuseofrefrigerants,notablythe bansonthe

useofODS refrigerants,and localplanning regulationswhich restrict theuseof

refrigerantssuch

as

ammonia

and

hydrocarbons

in

certain

locations

or

applications.

Often,where there arepublic safety risks, theuseofHFC refrigerants is theonly

practicalsolution.

8.4.3 CONVERSIONOFEXISTINGODSREFRIGERANTSYSTEMS

Environmental regulations, have resulted in the banning ofODS refrigerants (CFC

andHCFC) refrigerants), and have affectedmanymillions of refrigerating and air

conditioningsystemswhichusethesesubstances.Theserefrigerantswillbenotbe

availabletoservicesystemsaftertheendof2009,thereforetherefrigerantwillneed

tobe

changed

to

enable

these

systems

to

operate

on

an

ongoing

basis.

It isnot feasible to replaceaCFCorHCFC refrigerantwithahydrocarbon (due to

fundamentalelectricalsafetydesignconsiderationstopreventexplosions),ammonia

(materialcompatibilitybecauseammoniacorrodescopper,andtoxicity),orcarbon

dioxide(highpressure/refrigerantperformancecharacteristics).

The nonavailability of CFC and HCFC refrigerantswill require that systems using

theserefrigerantsbereplacedortherefrigerantchangedforaHFCrefrigerantwith

similarpressureandperformancecharacteristics.Series400refrigerantshavebeen

developed,and

are

commercially

available,

as

replacements

for

CFC

and

HCFC

refrigerantsinexistingsystems(seetablein8.5).Achangeofrefrigerantmayrequire

anoilchange. (seebelow)

8.4.4 COMPRESSORLUBRICATINGOILCONSIDERATIONS

Refrigerationcompressorshavea longoperational lifewithminimal servicingover

the lifetime of the refrigeration system. An important contributor to compressor

reliability is the lubricating oil used. The interaction between the oil and the

refrigerantisimportant.

Duringsystemoperationsmallamountsof theoilarecarriedwith thecompressor


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8

discharge vapours from the compressor within the refrigerant vapour. It is

importantthatthisoilreturnstothecompressorforadequatelubricationofmoving

parts. To assure consistent and adequate oil return the oil has to have a good

solubility/miscibility relationship with the refrigerant. CFC and HCFC refrigerant

systems have traditionally used hydrocarbonbased compressor lubricating oils

(mineraloils

or

alkyl

benzene

based

oils,

or

mixtures.).

WhenHFCrefrigerantsweredeveloped(toreplacetheregulatedCFCsandHCFCs)in

the 1990s it was realised that these fluids did not have the required

solubility/miscibilitywithhydrocarbonbasedoils,andfamiliesofsynthetic(PAGand

POE) lubricants were rapidly developed that are miscible. All new HFC system

compressorsusethesenewlubricants.

Systems using hydrocarbon compressor lubricating oils, present a problem when

they have to be converted to HFC refrigerants. When using HFC refrigerants

lubricatingoil

in

the

old

system

has

to

be

totally

replaced

with

one

of

the

new

oils

(usually POE).A relatively low residual levelofHydrocarbonoil (usuallynotmore

than 5%) in the POE can be tolerated. To achieve these low levels the old

hydrocarbonoilhastobeflushedfromtheentirerefrigerationsystem.

Recently a group of hydrocarbon oiltolerant, zero ODP, HFC based refrigerant

mixtures/blendshasbeencommercialised.Thesefluidsdonotrequirethattheold

hydrocarbonbasedoilsberemovedfromthesystem,withobviousbenefitsinterms

oftheeaseofconversiontozeroODPrefrigerants.


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8.5 REFRIGERANTSCOMMERCIALLYAVAILABLE

Commercial Refrigerant Fuids (most commonly used)

Refrigerant ODS Boiling Point Replacement for Comment

(C)

Fluorocarbons

CFCs

R12 YES -29.0 - Banned

R502 YES -45.4 - Banned

HCFCs

R22 YES -40.8 - Regulated

R401A YES -33.4 R12 Regulated


R403B YES -49.9 R502 Regulated



HFCs

OEM R404A NO -46.5 R402, R403, R408 Requires POE oil

R507A NO -46.7 R402, R403, R408 Requires POE oil

R407A NO -45.0 R402, R403, R408 Requires POE oil

R407C NO -43.8 R22 Requires POE oil

R410A NO -51.6 OEM only Requires POE oil

Service

R413A NO -29.4 R401, R409 Mineral oil tolerant

R417A NO -39.1 R22 Mineral oil tolerant

R422A NO -46.5 R502, R402, R403, R408 Mineral oil tolerant

R422D NO -43.2 R22, Mineral oil tolerant

R424A NO -39.7 R22 Mineral oil tolerant

R426A NO -28.4 R401, R409 Mineral oil tolerant

R428A NO -48.4 R502, R402, R403, R408 Mineral oil tolerant

Non Fluorocarbon

R600 n-butane NO -0.5 OEM only Flammable

R600a i-butane NO -11.7 OEM only Flammable

R290 propane NO -42.1 OEM only Flammable

R1270 propene NO -47.6 OEM only Flammable

R717 Ammonia NO -33.3 OEM only Toxicity concerns

R744 CO2 NO -56.6 OEM only Triple Point at 5.2 bar(a)

Critical Temperature 31C


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8.6

LEAK

DETECTION

Loss of refrigerant from a system has a direct impact on global warming, and causes

inefficient and unreliable operation. In compliancewith Fgas Regulation (EN 842/2006)

operatorsofHFCrefrigerationsystemsmustpreventleakage,ensureleakchecksarecarried

out,repairany leaksassoonaspossibleandarrangeproperrefrigerantrecovery.Seealso

Part5of thisGuide.The legal requirementsarecoveredwithin theFGasRegulationsEN

842/2006,andtheBRACodeofPracticeforRefrigerantLeakTightness,whichalsoincludes

asectioncoveringrefrigerantdetectionsystemcertification.


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ThisGuideispublishedinthefollowingParts:

Part1

Introduction

Part2 SystemDesignandComponentSelection

Part3 SafetyRegulations,StandardsandDirectives

Part4 SystemInstallation

Part5 SystemCommissioning

Part6 SystemMaintenanceandService

Part7 SystemandComponentDecommissioningandWasteDisposal

Part8 RefrigerantsandRetrofitting

Part9 AssessmentofSkillsRelatedCompetenceandTraining

TheBRAandIORdisclaimallliabilitytoanypersonforanythingorfortheconsequencesof

anythingdoneoromittedtobedonewhollyorpartlyinrelianceuponthewholeoranypart

ofthe

contents

of

this

Guidance

document.


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British Refrigeration Association Institute Of Refrigeration

PublishedBy:

BritishRefrigerationAssociation

2WalthamCourt,MilleyLane,HareHatch,Reading,Berkshire,RG109THUnitedKingdom

TelNo:+44(0)1189403416 FaxNo:+44(0)1189406258

email:[email protected]

InstituteofRefrigeration

KelvinHouse,76MillLane,Carshalton,SurreySM52JR,TelNo: +44(0)2086477033 Fax

No:+44(0)2087730165

email:[email protected]

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