EngA AF Series

A
AF / DCU MANUAL
IOM-52 14 of 23 Apr 13 R2
NOTES:
1. SizesareODdimensions,TypeL,ACRrefrigerationtubing.
2. 3/4”(7/8”)notedabove:7/8”ACRtubingmayreplace3/4"asrequired.
3. Selectionsarebasedonequivalentlength.Equivalentlengthistheactuallengthplustheadditional
lossesinfeetduetofittings.SeeTable1forpressurelossesduetofittings.
(Ifnumberoffittingsisunknownanequivalentlengthestimatecanbemadebymultiplyingtheactual
pipingrunbyacomplexityfactorof1.5to2timestheactuallength.1.5timesforasimplesystemor
longrunsand2timesforaclosecoupledsystemoronewithalotoffittings.)
4. Forcompressorsorcircuitswithunloading(tandemcompressorsincluded).Alwayschecktubingsizes
foroilreturnattheunloadedconditions.Determinetheunloadedcapacityintonsandverifythatthe
selectedtubingisnotlargerthanmaximumrisersizeattheunloadedcapacity.
5. SelectionCriteriatodeveloptable.
Suctionline ‐ PDlessthan2°Ftemperaturepenalty.
Dischargeline‐ PDlessthan2.5°Ftemperaturepenalty.
Liquidline ‐ PDlessthan2°Ftemperaturepenalty,withvelocitylessthan350fpmtoavoidliquid
hammer.
Condensateline(condensertoreceiverifequipped‐velocitylessthan115fpm.(twophaseflow)with
notraps.
Maximumrisersizesarethelargestrecommendedtubingsizesforoilreturn.Sizesarebasedon75%
capacitytoallowforlowloadconditions.
Fordetailedevaluationofpipingsystems,guidelinesandpressurelossesconsultASHRAEhandbooks.
RefrigerationTable3 
Approximateeffectofgaslinepressuredropon
compressorcapacityandpower(ASHRAE
REFRGERATION2.3)
LineLoss Capacity RequiredPower
Suction % %
0°F 100 100
2°F 96.4 104.8
4°F 92.9 108.1
Discharge % %
0°F 100 100
2°F 99.1 103.0
4°F 98.2 106.3
RefrigerationTable4
Weightofrefrigerantinliquidlinesper100ftoftubing(100°F)
Liquid
Line
R134a
Lbs(kg)
R407C
Lbs(kg)
R410A
Lbs(kg)
3/8” 3.9(1.8) 3.6(1.6) 3.4(1.5)
1/2” 7.3(3.3) 6.8(3.0) 6.2(2.8)
5/8” 12(5) 11(2.3) 10(4.5)
7/8” 24(11) 23(10.4) 21(9.5)
11/8” 41(19) 39(18) 36(16)
13/8” 63(29) 59(27) 54(24)