# TO 

# OBSOLETE .1 

# 1990 TCP



# STANDARD

# for

V 

# CENTRIFUGALOR

• V 

# ROTARYSCREW

•

V 

# WATER-CHILLING PACKAGES

• __________



# i Standard 550-90 AIR-CONDITIONING ____________________

&REFRIGERATION INSTITUTE i I t• U

1501 WILSON BOULEVARD • ARLINGTON, VIRGINIA 22209

### IMPORTANT SAFETYRECOMMENDATION Itis strongly recommended that the product be designed, constructed, assem bled and installed in accordance with nationally recognized safety require ments appropriate forproducts covered by this standard. ARI, as a manufacturers’ trade association, uses its best efforts to develop standards, employing state-of-the-art and accepted industry practices. Iow ever, A does not certify or guarantee safety ofany products, components or systems designed, tested, rated, installed or operated in accordance with these standards or that any tests conducted under its standards will be nonhazardous orfree from risk.

I I



### ARI CERTIFICATION PROGRAM PROVISIONS Scope ofthe Certification Program All 

### water-cooled centrifugal and rotary screw water-chilling packages rated below 1600 tons at ARI Standard Rating Conditions, of the hermetic and open type. electric motor driven 60 Hz below 5000 volts, 

### as covered by this standard, are includedin the Certification Program. Included are chillers with singlebundle shells (single watercircuits or multiple condensers on a single watercircuit are included). It is recognized that more than one condenser can be used on a single watercircuit on a chiller. Certified Ratings The Certification Program ratings verified by test are: I. Capacities (ton) [kW], 2. PowerInputs perTon (kW/ton) [kW/kW], 3. Water Pressure Drops (see Section 5.1.8) (psi or feet ofwater) [kPaJ, all ofthe above at standard ratings conditions (see Section5.1.1) and at applicationratings 

### conditions (see Section 5.1.2) for both full and part loads (see Section 5.1.6 for part loadperformance requirements), 4. Integrated PartLoad Values (IPLV’s) (see Section 

### 5.1.6), and 5. ApplicationPartLoad Values (APLV’s) (see Section 5.1.6).

NOTE: This standard supersedes ARI Standard550-88

Price $22.00 © COPYRIGH1 1990, byAir-ConditioningandRefrigerationInstitute Printedin U.S.A. ‘%i RegisteredUnitedStatesPatentandTrademarkOffice

### SECTION Section 1. Section 2. Section 3. Section 4. Section 5. Section 6. Section 7. Table 1. Part Load Conditions forRating Figure 1. Allowable Tolerance Curves forFull and PartLoad Figure 2. IPLV and APLVTolerance 

### Curve /

APPENDIX A STANDARD REQUIREMENTS FORTESTING CENTRIFUGAL OR ROTARY SCREWWATER-CHILLING PACKAGES

APPENDIXB METhOD AND EXAMPLE OF CALCULATING INTEGRATED PART

- 

### LOAD VALUE I I 2 2 6 6. 

### 4 6 

### 7

Section Bi. Purpose 13 Section B2. Scope 13 Section B3. Equation and Definition ofTerms 13 Section B4. Example Calculations 14 Figure Bi. ExamplePartLoadFactor Curve 15 

# O?ERTYFIIS GOVERNMEIT ‘ 

### , 4 1P 

# 4 V 

# ) OBSOLETE

TABLE OF CONTENTS PAGE 

## r Purpose Scope Definitions StandardEquipment Published Rating Requirements RefrigerantDesignation Voluntary Conformance

Section Al. Section A2. Section A3. Section A4. Section AS. Section A6. Section A7. Section A8. Purpose 8 Scope 8 Definitions 8 Test Methods 8 Instruments 8 .Measurements 9 TestProcedure 10 Calculation ofResults 12

### ARI STANDARD 550-90 

# CENTRIFUGAL OR ROTARY SCREWWATER-CHILLING PACKAGES

Section 1. Purpose 1.1 Purpose. The purpose ofthis standard is to estab lish, forcentrifugal orrotary screwwater-chillingpack ages: definitions and nomenclature; a description of what constitutes such a package; published rating con ditions; standard requirements for testing and a basis for published ratings; and proper refrigerant designa tion in systems. 1.1.1 This standard is intendedforguidance ofthe industry, including specifying agencies, manufac turers, installers, contractors and users. 1.2 This standard is subject to review and amendment as the technology advances.

Section 2. Scope 2.1 Scope. This standard applies to centrifugal or ±0- 

### tary screw water-chillingpackages as defined in 3.2. 2.1.1 This standard applies to both hermetic and open centrifugal or rotary screw water-chilling packages which have continuous capacity modula tion, whether driven by an electric motor, steam turbine orotherprime mover. 2.1.2 This standard does not include sanitary pro visions necessary for the handling of potable Iiq uids.

Section 3. Definitions 3.1 Definitions in ASHRAE “Terminology ofHeating, Ventilation, Air-Conditioning and Refrigeration” apply except as indicated by the definitions following in this section. 3.2 CentrifugalorRotaryScrewWater-ChillingPackage. A Factory-designed and prefabricated assembly (not necessarily shipped as one package) of one or more compressors, condensers, and watercoolers, withinter connections and accessories. 3.2.1 An open centrifugalorrotaryscrew compres sor is 

### definedashaving ashaftorothermovingpart extending through a casing to be driven by an out side source ofpower, thus requiring a stuffingbox, shaft seal, or equivalent, between a fixed and a movingpart. 3.2.2 A hermetic centrifugal orrotary screw com pressorisdefined as consistingofacompressorwith itsprime moverand drive, all ofwhich are enclosed as to operate in the refrigerant atmosphere. 3.2.3 A purge is a device for removing non-con densable gas and moisture from refrigerant con densers. 3.2.4 Apump-outsystem is a system which facili tates transferofrefrigerant from one heat exchan ger to another orto orfrom a storage vessel. 3.3 FoulingFactor. The thermal resistance due to foul ing accumulated on the heattransfersurface. 3.3.1 FieldFoulingAllowance. Provisionforantic ipatedfouling duringuse specifiedin hrsqftF/Btu [m 2 °CIWJ. 3.4 IntegratedPartLoadValue (IPLV). A single num ber part-load efficiency figure of merit calculated per 

### the method described in 5.1.7 referenced to Standard Rating Conditions (See Table 1). 3.5 Application Part Load Value (APLV). A single number part-load efficiency figure ofmerit calculated per the method described in 5.1.7 referenced to Se lectedApplication Rating Conditions (SeeTable 1). 3.6 Published Rating. A statement in the form ofcat alogs or computer output, of the assigned values of those performance characteristics, under stated rating conditions, by which a Unit may 

### be chosen to fit its 

### application. These values applyto allunits oflikenom inalsize andtype (identification) producedbythe same manufacturer. 3.6.1 A Standard Rating is a rating at Standard Rating Conditions based on testdata. 3.6.2 An application rating is a.rating at applica tionrating conditions (otherthan Standard Rating Conditions). 3.6.3 SelectedApplication Ratingis arating devel oped at specific application conditions. 3.7 Manufacturer. Themanufacturerofthewater-chill ing package unless otherwise stated. 3.8 “Shall”, “Should”, or “ItIs Recommended” shall be interpreted as follows: 3.8.1 Shall. Where “shall” is used for a provision specified, that provision is mandatory if compli ance with the standard is claimed. 1

### ARI STANDARD 550-90_

3.8.2 Should or It Is Recommended. “Should” or “it is recommended” is used to indicate provisions which are not mandatory hut which are desirable as good practice.



### Section 4. Standard Equipment 4.1 A centrifugal or rotary screw water-chilling pack age shall include the following standard equipment: I. Compressor and drive assembly consisting ofone ormore centrifugalorrotaryscrewsingleormulti stage compressor(s) with necessary lubrication system(s). a. Hermetic drive: Prime mover, with gears and couplings as necessary integral with the com pressor. b. Open drive: Prime mayer, with gears and cou plings as necessary (except when furnished by others). 2. Refrigerant condenser: A refrigerant-to-water, refrigerant-to-airorevaporatively cooled heat ex changer. Refrigerant-to-water condensers shall have a water side suitable for a working pressure of 150 psig [1034 kPa] or more. 3. Cooler (refrigerant evaporator): A refrigerant-towater heat exchanger; with water side suitable for aworkingpressureof 150psig [1034kPa] ormore. 4. Controls as necessaryto regulatepackage capacity and meet applicable safety requirements specified by others.

Section 5. Published Rating Requirements 5.1 Published Ratings. Published ratings consist of Standard Ratings and application ratings, whetherpub lished in catalogs or as computer output. 5.1.1 &andard Rating C’ondirions. Standard Rat ings shall be determined at Standard Rating Con ditions, as follows: Cooler (All Condenser Types) Leaving chilled water

temperature 44 F [6.7°C] Cooler water-side field fouling

allowance 0.00025 hr sq ft F/Btu [0.000044m 2

. °CIW] Cooler refrigerant-side fouling factor allowance 0.0000 hr sq ft FIBtu 10.0000 m 2 • °C/W] Chilled water flow rate 2.4 gpmlton 

## 10.043 Us per kw] Condenser (Water-cooled) Entering condenser water temperature 85 F [29.4°C] Condenserwater-side field fouling allowance 0.00025 hr sq ft F/Btu [0.000044 m 2 °C/WJ Condenser refrigerant-side fouling factor allowance 0.0000 hr sq ft F/Btu [0.0000 m 2 

### °C/W] Condenserwater flow rate 3.0 gpm/ton [0.054 L/s foreach kW capacity] Condenser (Ajr-cooled) Air entering condenser 95 F [35.0°C] dry bulb Condenser refrigerant-side fouling factor allowance 0.0000 hr sq ft F!Btu [0.0000 m 2 °C/W] Condenser air-side fouling factor allowance 0.0000 Barometric Pressure

... 29.92 in. Hg [101 kPa] Condenser (Evaporatively-cooled) Airentering condenser 75 F [23.9°C] wet-bulb Condenser refrigerant-side fouling factor allowance 0.0000 hr sq ft F/Btu [0.0000 m 2 °C/Wj Condenser air-side field fouling allowance 0.00000 hr sq ft F/Btu [0.0000 m 2 Barometric Pressure 29.92 in. Hg [101 kPa]

5.1.2 Application Rating Conditions. It is recom mended that application ratings (at other than Standard Rating Conditions) include ratings at the following range ofconditions:

All Condenser Types Leaving chilled water temperature 40-48 F [4.4 to 8.9°C] increments 2 F or less

.. [1°C or less] Condenser (Water-cooled), Entering condenserwater temperature 80-95 F [26.7 to 32.2°C] in increments 5 F or less [3°C or less] Condenser (Air-cooled) Entering air temperature to the condenser 85-115 F [29.4 to 46.1°C] dry bulb in increments 10 F or less [6°C or less] 

# .ARI STANDARD 550-90 

### Condenser (Evaporatively-cooled) Entering air temperature to condenser 70-80 F [21.1 to 26.7°C] wet bulb in increments 2.5 F or less

.... 

### [1.5°C or less]
5.1.2.1 

### Field Fouling Allowances. When appli cation ratings are published, they shall include those with field fouling allowances as specified in 

### 5.1.1. Additional application ratings, or means ofdeterminingtheseratings, atotherfield fouling allowances may also be published (See 

### 5.2). 5.1.3 

### Determination ofRatings. Published ratings shall be determined fromtestresults in accordance with the following:
a. Cooler and condenser water-side heat trans fer surfaces shall be considered clean during testing. Tests will be assumed to reflect a fouling factor of0.000 hr sq ft F/Btu [0.0000
m 2 °C/W]. b. To determine published ratings at any field fouling allowance from test data at a fouling factor of 0.000 hr sq F/Btu [0.0000 m 2 W], the calculations for fouling adjustment described in ARI Standard 

### 450 for 

### WaterCooledRefrigerantCondensers, Remote Type and ARI Standard 480 for 

### RefrigerantCooledLiquidCoolers, Remote Type shall be used. 5.1.4 

### Net Tons. The published tons of refrigera tion [kW] are considered as net usable tons [kWj to the customer’s system. 5.1.5 

### PowerInput. Published powerinput require ments shall be the power required from the cus tomer’s powersource and shall include the average power required by all components ofthe package including the purge, oil pumps, oil heaters, motor starters, frequency converters and controls fur nished by the manufacturer. Power required by water pumps shall be excluded. 5.1.6 

### Part Load Performance. Part load perfor mance of a centrifugal or rotary water-chilling package, may be presented in three ways:

a. Integrated Part Load Value (IPLV) which is based on Standard Rating Conditions (See Table 1). b. Application Part Load Value (APLV) which is based on a Selected Application Rating Condition (See Table 1).
c. Separate part load data point(s). 5.1.6.1 IPLV and APLV values shall be deter mined by test at the conditions prescribed inTa ble 1. 5.1.6.2 For water-chilling packages covered by this Standard, Part Load Values (IPLV or APLV) shall be calculated as follows: a. Determine the kW/ton at. 100 percent; 75 percent; 50 percent and 

### 25 percent load points atthe conditions specifiedinTable 1.
b. Use the following equation to calculate IPLV orAPLV: IPLV or APLV = 0.05A + 0.3B + 0.4C + 0.25D (1) where: A = kW/ton at 100% B = kW/ton at 75% C = kW/ton at 

### 50% D = kW/ton at 

### 25% For a derivation ofequation (1) see Appendix B.
c. If the package cannot be operated at the 25% load point, operate it atminimum ca pacity with the entering fluid temperature (EWT) corresponding to 25% capacity conditions. Then calculate kW/ton as the measureu kW dividedby

### 25% ofthe 100% load capacity obtained by test. 5.1.6.3 Part load performance data shall be pre sented in terms of percentage of rated power input (kW or bhp) [kWJ versus percentage of rating capacity (tons) [kWj. Water temperatures shall be adjusted for field fouling allowance per A7.3. If presented, and not otherwise stated, part load performance shall be based on the IPLV conditions shown in Table 1. 5.1.7 

### OffCycle Requirements. Off cycle power, if presented, shall be time averaged power input (kW). 

### 5.1.8 PublishedRatingData. Publishedrating data (in catalogs or computer output) shall include package designation(s), Standard Ratings foreach such package and any additional application rat ings elected. The rating at any condition shall In clude:



### Compressor/Cooler (All Condenser Types) a. Nominal voltage and frequencies for which ratings are valid. b. Refrigerant selection for which ratings are valid. c. Capacity, tons ofrefrigeration [kW]

3

### ARI STANDARD 550-90

Table 1. PartLoad Conditions for Rating IPLV APLV 

### Cooler(All Types) 100% load 

### LWT * 

### 44F [6.7°C] * Selected

### LWT

0% load 

### LWT 44F [6.7°C] Same as 100% load Flow rate (gpm) ** 2.4 gpm/ton [0.043 ** Selected gpmlton L/s per kW] Field fouling allowance (F.F.A.) 0.00025 As specified 

### Condenser (Water-Cooled) 100% load

### EWT * 

### 8SF [29.4°C] * Selected 

### EWT

0% load 

### EWT ***60F [15.6°C] ***60F 

### [15.6°C] Flow rate (gpm) [L’s] ** 3.0 gpmlton [0.054 ** Selected gpmlton



### • Us perkW] [L’s perkW] F.EA. 0.00025 As specified 

### Condenser (Air-Cooled) 100% load EDB 9SF 

### [35.0°C] Selected EDB

0% load EDB ***55F [12.8°C] ***55F [12.8°C] F.F.A. 0.000 0.000 

### Condenser (Evaporatively-Cooled) 100% load

### EWB 75F [23.9°C] Selected EWB

0% load

### EWB ***5 [10.0°C] ***50F [10.0°C] F.FA. 0.000 0.000 Corrected forfield fouling allowance by using the calculation method described in A7.3. The flow rates (gpm) are to be held constant at full loadvalues for all part load conditions. *Condenserentering fluid or airtemperature varies linearlyfrom 100% load values to 0% load values. JWTis leaving water (liquid) temperature. EWTis entering water (liquid) temperature. EDB is entering air dry bulb temperature. EWB is entering airwet bulb temperature. F.F.A. is field fouling allowance in hrftF/Btu [m 0 C,W]

d. Power input requirements, compressor shaft horsepower (ifprime mover is not supplied) Kilowatt input for open or hermetic drives, kW (see 5.1.6). Leaving chilled water temperature, F [°C] Cooler liquid pressure drop (inlet to outlet), psi or feet ofwater [kPa] h. Pass or baffle arrangements and rated water flows, gpm [Us] i. Maximum and minimum recommended flow rates
for.relatively clean water 

### Condenser (Water-cooled)

V a. Entering condenser water temperatures, F [°C] b. Condenser waterpressure drop (inlet to Out let), psi or feet ofwater [kPa]
c. Statement offield fouling allowances in heat exchanger d. Pass or baffle arrangements and rated water flows, gpm [L’s]
e. Maximum and minimum recommended flow rates for relatively clean water. (Any limita tion on waterflow rates to minimize erosion, corrosion, orfouling should take into consid eration the quality ofthe water and any ma terials it may have in suspension, tube mate rial, as well as the number of expected operating hours peryear.)

V 

### Condenser (Ajr-cooled)
a. Entering airdry-bulb temperature to the con denser, F [°C} b. Condenser fan motor power consumption, kW

V 

### Condenser (Evaporatively-cooled)
a. Entering air wet-bulb temperature to con denser, F [°C] e. f.



### 4ARI STANDARD 550-90

Rated Full Load Performance Rated ca pacity Rated b. Condenser fan motor power consumption, See Figure 1 “Allowable Tolerance Curve for Full kW and Part Load” for graphical representation only.
c. Condenser spray pump power consumption, kW d. Statement offield fouling allowance on heat 

### 5.4.2 Full Load. Published ART ratings shall be exchanger. such that any production package shall, upon test have a full load capacity not less than 

### 100 percent 

### 5.2 Water-Side Fouling, of its rated capacity less the allowable tolerance and a full load powerinput perton (kW/ton) [kW/ 5.2.1 

### Fouling at Standard Rating Condition. The kW] ofnot more than 100 percentofits rated kW/ choice of0.00025 hr sq ft F/Btu [0.000044 m 2 °C/ ton [kW/kW] plus the allowable tolerance. The al W] for coolers, and condensers for the Standard lowable tolerance shall be determinedby the equa Rating Condition field fouling allowance which is tion specified in 

### 5.4.1. the basis forpublished rating conditions (see 

### 5.1.1 and 

### 5.1.2.1) provides equipment selections which Water pressure drop in the cooler and condenser anticipate the effectoftypical foulingin coolerand shall notexceed 115 percentofrated pressure drop condenser water circuits. Fouling tends to reduce at rated gpm, 

### [Us]. capacity and increase power consumption. An ap plication should remain within the limits of the 

### Example (Fullload): (in U.S. Standard Units only field fouling allowance ifacceptable water quality for clarity) is maintainedbytreatment, andtheheatexchanger surfaces are periodically cleaned. 5.2.2 

### Additional Fouling. Conditions such as = 100 tons waterhardness, organicmaterial, suspended solids and/or watervelocity may necessitate the use ofa power = 70 kW greater field fouling allowance than that provided Cooling DTFL = 1OF in the Standing Rating ofequipment. 70 kW 

### 5.2.3 Adjustments for Additional Fouling. Pub- kW/ton =

— = .70

— 100 ton lished ratings may include the effects ofadditional field fouling allowance. Such ratings shall be de- Allowable Test Performance— termined by using the methods described in para graph 5.1.4b. Tolerance = 

### 10.5

— (.07 x 100%) +(1500) 

### 5.3 Verification ofCapacity and Power Requirements. (10 X 100%) Where verification ofcapacity and powerrequirements is required, it shall be by test in accordance with the method set forth in Appendix A to this standard.

- = 10.5

— 7 + 1.5 = 5% 5.4 

### Tolerances. (100 5) x 100 Mm. allowable capacity

= 100 

### 5.4.1 Allowable Tolerance. The allowable test tol-

= 95 tons erance on capacity (tons) [kW], power input per ton (kW/ton) [kW/kW] and heat balance, shall be (100 + 

### 5) .70 

### Max. allowàblë kW/ton = determined from the following equation: 100 Tolerance in percent tons [kWJ, percent kW/ton = .735 kW/ton [kW/kWJ orpercentheatbalance Max. kW at mm. capacity = 

### .735 x 95 = 69.825

= 10.5

— 0.07 x % FL + (1500/(DTFI.. x % 

### FL)) (U.S. Standard Units DTFL in F.) 

## [ = 10.5

— 0.07 x % FL + (833.3/DT x % FL)] 5.4.3 

### PartLoad. Thetolerance on partloadpower [SI units DTFL in 

## °C] input per ton (kW/ton) shall be the tolerance for kWfton determined by the equation specified in where FL = Full Load 

### 5.4.1. DTFL = Difference between entering and leaving chilled water temperature 

### Example (Partload): (in U.S. Standard Unitsonly at full load, F [°C]. for clarity) )

### MU STANDARD 550-90



### z LU 0 LU 0 LU C) 

### z LU -J 

### 0

= 10.5

— 3.5 + 3 = 10% 

### (1500) 10 x 50%)

Max. allowable kW/ton = (100 x .70

= 0.77 kW/ton
5.5.4 !PLV and APLV Tolerance. The allowable tolerance on IPLV and APLV shall be determined by the following equation: Allowable Tolerance (percent) 6.5 + 35IDT DTFL in F 

# I = 6.5 + l9.4!DTj DTFL in DTFL as specified in 5.4.1 see Figure 2. “IPLV and APLV Tolerance Curve” The single number IPLV or APLV, calculated for the part load conditions which apply, shall not ex ceed the rated IPLV or APLV by more than the allowed tolerance.
Section 6. Refrigerant Designation 6.1 Therefrigerantdesignation shallbe specifiedonthe package nameplate. 6.1.1 The refrigerantdesignation shall be in accor dance with the ANSI/ASHRAE 34-1989 Standard NumberDesignation ofRefrigerants.

Section 7. Voluntary Conformance 7.1 Conformance. While conformance with this stan dard is voluntary, conformance shall not be claimed or implied for products or equipment within its Purpose (Section 1) and Scope (Section 2) unless such claims meet all ofthe requirements ofthe Standard. Figure 1. Allowable Tolerance Curves ForFull And Part Load -. 

# 0

DTFL (SEE 

### 5.4.1) PERCENT FULL LOAD

Rated Part Load Performance

50% capacity 50% power k\V/ton Full load DTFL = 50 tons

= 35kw

= .70 kW/ton

= 1OF Allowable Test Performance Tolerance = 10.5

— (.07 

### x 50%) +

6___________________________________________

ARI 

### STANDARD 550-90 Figure 2. IPLV and APLV Tolerance Curve 20 18 16 14 w C.) 12 w LU C) 

### z LU -J 

### 0 6 4 2 0 16 17 18 19 20



### DTFL (SEE 5.41) COOLER DTAT FULL LOAD, F

7 3 4 5 6 7 9 10 11 12 13

### ARI STANDARD 550-90 

### APPENDIX A STANDARD REQUIREMENTS FOR TESTiNG CENTRIFUGAL OR ROTARY SCREW WATER-CHILLING PACKAGES 

# e

Section Al. Purpose A1.1 Purpose. The purpose ofthis appendix is to pre scribe a method of testing centrifugal or rotary screw water-chilling packages to verify capacity and power requirements at a specific set ofconditions. It is intended that this testing will occur where instru mentation and load stability can be provided. Itis nottheintentofthis standardto provide fortesting in typical field installations where steady state condi tions are often difficult to achieve and provisions for measurement are not made.


### A2. Scope A2.1 

### Scope. This appendix applies to centrifugal or rotary water-chilling packages used to chill water, as defined in Section 3 ofthis standard.


### Section A3. Definitions A3.1 Definitions for this appendix are identical with those in Section 3 ofthis standard.



### A4.1 TestMethod. A4.1.1 The test will measure net cooling capacity (tons ofrefrigeration) and energyrequirements, at a specific set ofconditions. A4.1.2 To confirm that steady-state conditions have been established at the specific set ofcondi tions and within the tolerances set forth in A7.2, three sets ofdata shall be taken, at approximately five-minute intervals. To minimize the effects of transient conditions, test readings should be taken as nearly simultaneously as possible. A4.1.3 The test shall include 

# a measurement of the net heat removed from the, water as it passes throughthecoolersbydeterminationofthe follow ing:
a. Waterflow rate b. Temperature difference between entering and leaving water A4.1.4 The heat removed from the chilled water is equal to the product of the chilled water flow rate, the water temperature difference, and the specific heat ofwater. A4.1.5 The test shall include the determination of the compressor power requirement. This power shall be determined by measurement ofelectrical input to motor drive (see 5.1.6). For motors sup plied by others the determination of compressor shaft horsepower input shall be as outlined in the test procedure. For air-cooled or evaporatively cooled condensers, thetest shall include the deter mination ofthe condenserfan andcondenserspray pump powerrequirements. 

### A4.1.5.1 Non-Electric Drive. Where turbine or engine drive is employed, compressor shaft horsepower input shall be determined from steam, gas, oroil consumption, atmeasured sup ply and exhaust conditions, and prime mover manufacturer’s certified performance data. 

### A4.1.6 In addition to the determination .of net heatremovedandenergyinputrequired, datashall be taken to prepare a heat balance to substantiate the validity ofthe test. 

### A4.2 Condition ofHeat TransferSurfaces. A4.2.1 Tests conducted in accordance with this standard may require cleaning (in accordance with manufacturer’s instructions) of the heat transfer surfaces. The as tested foulingfactors shall then be assumed to be 0.0000 hr sq ft F/Btu [0.0000 m 2 °C/W].


### Section A5. Instruments A5.1 Instruments shallbe selectedfromthetypes listed 

### in ASHRAE StandardMethodofTesting Liquid Chill ing Packages (American Society ofHeating, Refriger ating and Air-Conditioning Engineers, Inc. Standard 30-78). 

### A5.1.1 Accuracy ofinstruments selected shall be in accordance with that specified in ASHRAE Standard 30-78. A5.1.2 Temperature measurements shall be made in accordance with ASHRAE Standard 

### Measure ments Guide—Sçction on Temperature Measure ments (American SocietyofHeating, Refrigerating and Air-Conditioning Engineers, Inc. Standard 

### 41.1-86). A5.L3 Flowmeters shall be constructed and in stalled in accordance with the applicable portion 

### Section A4. TestMethods



# .ARI STANDARD 550-90
ofthe latest edition ofthe ASME “Fluid MetersTheirTheory and Application.” lurbine flow me ters may also be used in accordance with ANSI! ISA-PR31.1 (latest edition) “Recommended Prac tice Specification, Installation, and Calibration of Turbine Flowmeters.” A5.1.4 Scales for analog meters shall be such that readings will be at least one-half offull scale de flection. All instruments, including gages and ther mometers shall be calibrated overthe range oftest readings. A5.1.5 Pressure measurements shall be made in accordance with ASME Power Test Code FTC 19.2, “Instruments and Apparatus, Part 2, Pres sure Measurement.” 

### Section A6. Measurements A6.1 

### Data to be recordedduring the test: A6.1.1 

### Test Data. Compressor/Cooler (All Condenser Types)
a. Temperatureofwaterentering cooler, F [°C] b. Temperature ofwater leaving cooler, F [°C]
c. Chilled waterflow rate, gpm or lbs/hr [L/sJ d. Power input to compressor, kW or e. Steam consumption ofturbine, lbs/hr [kg/hr} Steam supply pressure, psig [kPa] Steam supply temperature, F [°C] Steam exhaust pressure, psig or inches Hg. vac. [kPa] or f. Gas consumption of turbine or engine, therms or cu ft per hr, [L/s] and calorific value, Btu per cu ft, [J!L], or g. Fuel consumption of diesel or gasoline en gine, gallons perhr, 

### [L’s] and calorific value, Btu pergallon 

### [J/L] h. Coolerwaterpressure drop (inletto outlets), psi orfeet ofwater [kPa]. i. Electrical power input to controls and auxil iary equipment, kW 

### Condenser (Water-cooled)
a. Temperature ofentering condenser water, F [°C] b. Temperature of leaving condenser water, F [°C]
c. Condenser water flow rate, gpm or lb/hr [L/ s] d. Condenserwaterpressure drop (inlet to out let), psi orfeet ofwater [kPa]. Condenser (Ajr-cooled)
a. Dry-bulb temperature ofairenteringthe con denser, F [°CI b. Condenser fan motor power consumption. kW
c. Barometric Pressure, in. Hg [kPa] 

### Condenser (Evaporarively-cooled)
a. Wetbulb temperatureofairenteringthe con denser, F[°C] b. Condenser fan motor power consumption, kW
c. Condenser spray pump power consumption, kW d. Barometric pressure, in. Hg [kPa] A6.1.2 If chilled water is used to cool the com pressor motor or for some incidental function within the package, the temperature and flow measurements of chilled water must be made at points beyond such take-offs and returns, so that the measured rise reflects net cooling capacity. A6.1.3 Ifcondenserwateris used to cool the com pressormotororforsomeotherincidental function within the package, the temperature and flow measurements of condenser water must be made at points ahead of such take-offs and returns, so thatthemeasuredrisereflects gross condenserheat rejection. A6.2 

### Auxiliary data to be recordedfor 

### general infor mation. A6.2.1 Nameplate data including make, model, size and refrigerant, sufficient to completely iden tify the water-chilling package. A6.2.2 Compressor driver or input rpm for opentype compressors. A6.2.3 Ambient temperature at test site, 

### F[°C] A6.2.4 Actual voltage, and currentin amperesfor each phase, ofall electric motordrive. 

### A6.2.5 Motor, engine orturbine nameplate data. A6.2.6 Pressure, temperature and exhaust pres sure for steam turbine drives. A6.2.7 Fuel gas specificationforgas turbine drive, including pressure, in. water [kPa]. A6.2.8 Heat balance for A7.4


### A6.3 Record Data. A6.3.1 Date, place and time oftest. 9

### ARI STANDARD 550-90.

A6.3.2 Names of test supervisor and witnessing personnel.

Section A7. Test Procedure A7.1 

### Preparationfor Test. A7.1.1 Thecentrifugalorrotaryscrewwater-chill ingpackage, which

### has been completelyconnected in accordance with the manufacturer’s instructions and is ready for normal operation, shall be pro vided with the necessary instruments. A7.1.2 The test shall notbe starteduntil non-con densabies have been removed from the system. A7.1.3 Atthemanufacturersoptioncondenserand cooler surfaces may be cleaned as provided in A4.2.1. 

### A7.2 Operation andLimits. A7.2.1 Start the system and establish the testing conditions in accordance with the following toler ances and instructions:


### a. Cooler (All Condenser Types) (1) The chilled water flow shall not deviate more than 

### ±5 percent from that speci fied. (2) The individualreadings ofwatertemper-

• ature leaving the cooler shall not vary

from the specified values by more than 

### 0.5 F [0.3°C]. Care must be taken to in. sure that these water temperatures arc the average bulk stream temperatures. 

### (3) The leaving chilled water temperature shall be adjusted by an increment calcu latedperA7.3 correspondingto the spec ified field fouling allowance. (4) Part load test capacity must be taken within ±2% ofthe full load tons at the specified part load capacity.


### b. Condenser (Water-Coaled) (1) The water flow through the condenser shall not deviate more than ± 

### 5 percent from that specified. (2) The individual readings ofwatertemper atures enteringthe refrigerantcondenser shall not vary from the specified values by more than 0.5F [0.3°C]. Care must have been taken to insure that these water temperatures are the average bulk stream temperatures. (3) The entering condensing water tempera ture shall be adjusted by an increment calculatedperA7.3 corresponding to the specified field fouling allowance.


### c. Condenser (Air- orEvaporatively-Cooled)
The individual readings ofwater temperature leaving the cooler and the saturated refrigerant condensing temperature corresponding to the compressor dis charge pressure (regulating the condenser air flow if necessary) shall not vary from the specified values by more than 

### 0.5 F [0.3°C]. Care must be taken to insure that the cooler water temperature is the average bulk stream temperature and the condensing temperature is measured as close to the compressor discharge port as practical. For an evaporative condenser calculate an appropriate correction to be applied to the correspond ing specified field fouling allowance. 

### d. Miscellaneous (1) For electrically driven machines, voltage 

### and frequency at the unit terminals shall bemaintained atnameplatevalueswithin tolerances of ± 10% on voltage and 

### ±1% on frequency. (2) For steam-turbine driven machines, steam conditions to the turbine, and con denser pressure or vacuum, shall be maintained at nameplate values. (3) For gas-turbine or gas-engine operated machines, gas pressure to turbine or en gine, and exhaust back-pressure at the turbine or engine shall be maintained at name-plate values. (4) In all cases, the governor, if provided, shall be adjusted to maintain rated com pressor speed. 

### A7.3 Methodfor Simulating Field Fouling Allowance atFull and PartLoad Conditions. A7.3.1 Obtain the log mean temperature differ ence (LMTD) forthe cooler and/or condenser us ing the following equation at the specified field fouling allowance (ff 5 ).
LMTD

= in (1 ± S)
A7.3.2 Derivation ofLMTD:

= (ts

— ce)

— (t 5

— ç,,) LMTD 

# inIc—_t1 c

— 

### t_,J (Al) 

# S

.)

.ARI STANDARD 55O-9O”
(t,

— t)

— tc,j) + (tc,i

— 

## L t, —t,

The incremental LMTD (ILMTD) is determined using the following equations:
ILMTD = if,,,

# () (A2)

where: ff = specified field fouling allowance q = Total heat rejection rate forcondensers or net refrigeration capacity for coolers Btuh [W]. A = Total heat transfer surface, sq ft 

## [m 2 1 where: A = A. for fouling inside tubes A = A, for fouling outside tubes A7.3.3 The water temperature difference TD needed to simulatethe additional fouling, TD, can now be calculated:

TD = 

### S,,,

— S (A3a) TD, = 

# s,

— - R (A3b)

“ e—l

= LMTD

— ILMTD Where: S = small temperature difference as specified S = small temperature difference as tested in cleaned condition The water temperature difference, TD, is then added to the condenser entering water tempera ture or subtracted from the cooler leaving water temperature to simulate the additional fouling fac tor. A7.3.4 Example—Condenser Fouling Inside Tubes (in U.S. Standard units.only, for clarity)

Specified field fouling allowance ff 5 = 0.00025 hr sq ft FIBtu Condenser load, q = 2,880,000 Btuh Specified condenser leaving water temp. T 1 = 95F Specified condenserentering watertemp. = 85F lnside* tube surface area, A 1 = 550 sq ft *(Since fouling is inside tubes in this example) Saturated condensing temperature. ç = IOIF

= t,

— t, = 101 —95 = 6°F R ç,

— t_e = 95—85 = 10°F LMTD = R (Al) In (1+ RIS) 10

— 10.2

— In (1 + 10/6) = if,,, = 0.00025 ILMTD 

# () (A2) 12,880,000\

= 0.00025

# 1 550 

# )

= 1.31°F TD,, = ,, — R (A3b) 1 e—1 Where:

— R

- LMTD

- ILMTD

= 6.0

— 4.8

= 1.2°F The entering condenser water temperature for testing is then raised 1.2Fto simulate the field foul ing allowance of0.00025 hr sq ft °F/Btu. The en tering condenser water temperature will be 85 + 1.2 or 86.2F. A7.3.5 Symbols and Subscripts. The symbols and subscripts used in Equations Al through A3b are as follows: Symbols: Where: R

A = Total heat transfer surface, sq ft 

## [m 2 1 A 0 /A, = Ratio ofoutside to inside surface area
e = Base ofnatural logarithm q = Total heat rejection rate,. Btuh [W]
r = Heat transfer resistance (hrft 2 F/Btu) [m 2 °C/W] R = Water temperature range = absolute value (t,,, 1

— twe,) F[°C] S = Small temperature difference = abso lute value (t 3

— F [°C]
t = Temperature, F [°C] U = Overall heat transfer coefficient (Btu perhr, sq ft. F) [W1m 2 °C] ff, = specified field fouling allowance 11

### ARI STANDARD 550-90 Subscripts: a = 

### additional fouling
e = 

### entering
c = 

### cleaned f = 

### fouled orfouling

= 

### inside
o = 

### outside

= 

### leaving
s = 

### saturated vapor w = 

### water sp = 

### specified

A7.4 HeatBalance-Substantiating Test. A7.4.1 CalculationofHeatBalance. Inmostcases, heat losses or heat gain caused by radiation, con vection, bearing friction, oil coolers, etc., are rel atively small andmay ormay notbe consideredin the overall heatbalance. Omitting the effect of the small heat losses and gains mentioned above the general heat balance equation is as follows:

where qe.., ± winpul = 

### q

q,, = 

### net cooling capacity of liquid. cooler, tons [kWj

= 

### compressor work input as defined inParagraphs (a), (b), or(c)below q = 

### netheatrejectedtothecondenser, tons [kWJ
a. In a hermetic package, where the motor is 

### cooled by refrigerant, chilled water or con denserwater, the motorcooling load will be included in the measured condenser load, hence

W,,,, = 

### electrical power input to the compressor motor expressed in tons [kWl b. In apackage using an open-type compressor with motorand external geardrive: ‘‘input =

— qgear 

### and

W,,, = 

### power input to the compressor shaft, expressedin tons [kW] qmo,or = 

### powerdeliveredbyprimemover expressed in tons [kW]

qgear = 

### friction loss in gear box, tons [kWJ The value of qprjme mover 

### shall be determined from the power input to prime mover using certified data from the prime mover manu facturer. The value of qge.r 

### shall be determined from certified gear losses provided by the gear manufacturer.
c. In apackage using an open-type compressor with direct drive and the prime mover not furnished by the manufacturer: FordeterminationofW 10 , forturbineoren gine operated machines, the turbine or en gine manufacturer’s certified power input! outputdata shallbe used.

W,,, 3 , = 

### power input to the compressor shaft, expressedin tons [kWJ In the case ofmotordrive:

= 

### power measured at motor ter minals. A7.4.2 Percent Heat Balance. Heat balance, in percent, is defined as: 

### q,, +

—q,., x 100 (A4)


### For anytestofaliquid cooledchillertobe accept able, theheatbalance (percent) shallbewithin the allowabletolerancecalculatedper5.4.1 forthe ap plicable conditions. For air or evaporatively cooled condenser, it is impractical to measure heat rejection in a test, therefore a heat balance cannotbe calculated.
Section A8. Calculation ofResults A8.1 Capacity andPower. A8.1.1 Thecapacityintons [kW] shallbeobtained bythe following equations:
c w(t

— t 1 ) 

### tons = 

### 12,000
where [kW = 

### 4.187 c/W (te

— t 1 )] 

### (AS)

c = 

### specific heat ofwater at average water temperature, Btu/(lb.F) [kJ/kg.°C]
w = 

### weightflowrate ofchilled water, lb per hr [kg/s] 

# 0)

0

12ARJ 

### STANDARD 550-90

= temperature of water entering the cooler, F [°C]

= temperature of water leaving the cooler, F 

## [°C] A8.1.2 Powerconsumption shall be determined as follows (consistent with 5.1.6):
a. For motor driven centrifugal or rotary screw compressors where the motor is supplied by the manufacturer, the compressor power in put shall be measured as close as practical to the compressor motor terminals. If a fre quency conversion device or motor starter is furnished as part of the compressor circuit, the compressor power input shall be meas ured at the input terminals ofthe frequency converter or motor starter. For remote start ers or frequency converters, line losses shall be subtracted. If the water-chilling package being tested is not equipped with the starter or frequency converter furnished for it, then a starter or frequency converter of similar type shall be used for the test. b. Powerconsumption ofauxiliaries shall be the time-averaged power consumplion of thesc devices during normal operation ofthe pack age. c. Foropen-type compressors, where the motor and/or gear set is not supplied by the manu facturer, or for engine or turbine drives, the compressor shaft input shall be determined as stated in A7.4.1 b or c. d. For air-cooled or evaporatively-cooled con densers, the additional condenser fan and condenser spray pump power consumption shall be measured as close as practical to the motors. A8.1.3 ValidityofTest. Calculate the heat balance foreach ofthe three testpoints (A4.l.2). All three heat balances must be within the tolerance speci fled (A7.4.2). Then average the data taken (A6.l.1) from the three test points and calculate capacity and power input per A8.1.1 and A8.I.2 using averaged data for reporting purpose.



### APPENDIX B DERIVATION OF INTEGRATED PART LOAD VALUES (IPLV AND APLV)
Section Bi. Purpose B1.1 Purpose. This appendix shows an example ofthe calculations for determining Integrated Part Load Val ues (IPLV) orApplication Part Load Value (APLV).


### Section B2. Scope B2.1 Scope. This appendixisforequipmentcoveredby this standard.


### Section B3. Equation and Definition ofTerms B3.1 General Equation (see5.1.7.2) IPLVorAPLV = 

### 0
. 1 (A) 

# 05 (B+c) F (C+D\ +0.3 2 

# 1 + 0.1D 

### (1) where: A = kW/ton [kW/kW] at 100% load point B = kW/ton [k-W/kW] at 75% load point C = kW/ton [kW/kW] at 50% load point D = kW/ton [kW/kW] at 25% load point And referring to Section B4-Calculation Example: (in U.S. Standard units only for clarity)
or simply IPLV orAPLV = O.05A + 0.3B + 0.4C + 0.25D
IPLV orAPLV = 0.05 (0.7) +0.30 (0.62) +0.40 (0.60) +0.25 (0.71) IPLVorAPLV = 0.035 + 

### 0.186 + 0.240 ± 0.178

= 0.639
13

### ARI STANDARD 550-90.
Section 84 EXAMPLE CALCULATIONS

% Full Mfrs. Net PLF Mfrs. Part Avg. Part PLF Diff. Avg. kW/ton x PLF Diff. = Weighted Load Cap.’ Cap. (Tons) 2 Factor 3 Load kW/ton 2 Load kw)ton Avg.
100% 500 1.0 0.70

= 0.66 (1.0—0.9)=0.1 0.66 x 0.1 = 0.066 75% 375 0.9 0.62

= 0.61 (0.9—0.4)=0.5 0.61 x 0.5 = 0.305 50% 250 0.4 0.60

-

= 0.66 (0.4—0.1)=0.3 0.66 x 0.3 = 0.198 25% 125 0.1 0.71

= 0.71 (0.1—0.0)=0.1 0.71 x 0.1 = 0.071 0%

—--- 0.0

— Single number IPLV or 0.64 APLV NOTES ‘Forcentrifugal and rotary screw type waterchilling packages as coveredby the standard, the kW/ton and capacities used to calculate the single number IPLV are to be at 100%, 75%, 50% and 25% offull load capacity. 2 A11 part load capacities and kW/ton are atpart load ratingconditions as determined by the standard. 3 Part load factorfrom Figure B-i. 

# 0

G

### ARI STANDARD 550-90



### FIGURE Bi EXAMPLE PART LOAD FACTOR CURVE

5 .____ 

# 1’ PART LOAD FACTOR CURVE

Lu > D 0 

# I LI -J 0
0

0 20 40 60 80 100
PERCENT OF FULL LOAD CAPACITY OR DISPLACEMENTAT PART-LOAD CONDITIONS