Zamil MAC-240 Instruction manual

MOBILE AIR CONDITIONING SYSTEM
Model: MAC-240
INSTALLATION,
OPERATION
&
MAINTENANCE
MANUAL

1
Contents Page
GENERAL ................................................................................................................................................................... 3
1. FOREWORD ........................................................................................................................................................... 4
2. STANDARD SPECIFICATION ............................................................................................................................... 4
2.1 BASE CHASSIS AND CONSTRUCTION ...........................................................................................................4-6
2.2 DIESEL ENGINE GENERATOR .........................................................................................................................6-8
2.3 UNIT PHYSICAL DATA ......................................................................................................................................... 9
2.3.1 UNIT SPECIFICATION SUMMARY .................................................................................................................. 10
2.4 AIR CONDITIONING SECTION ........................................................................................................................... 11
2.5 ELECTRICAL ENCLOSURE ASSEMBLY ........................................................................................................... 12
2.6 OPERATING FROM EXTERNAL POWER SOURCE.......................................................................................... 13
3. REFRIGERATION SYSTEM ................................................................................................................................. 13
3.1 GENERAL DESCRIPTION .................................................................................................................................. 13
3.2 REFRIGERATION CYCLE..............................................................................................................................13-14
3.3 MAJOR REFRIGERATION COMPONENTS ....................................................................................................... 15
3.3.1 SCROLL COMPRESSORS .........................................................................................................................15-17
3.3.2 CONDENSER COIL .......................................................................................................................................... 17
3.3.3 CONDENSER FAN ........................................................................................................................................... 17
3.3.4 CONDENSER FAN MOTOR............................................................................................................................. 17
3.3.5 EVAPORATOR COIL ........................................................................................................................................ 17
3.3.6 EVAPORATOR FAN ......................................................................................................................................... 17
3.3.7 HOT GAS BY PASS CONTROL ....................................................................................................................... 18
3.3.8 CRANKCASE HEATER .................................................................................................................................... 18
3.3.9 REPLACEABLE CORE FILTER DRIER ........................................................................................................... 18
3.3.10 SIGHT GLASS ................................................................................................................................................ 18
3.3.11 FAN CYCLE HEAD PRESSURE CONTROL.................................................................................................. 18
3.3.12 CONDENSER COIL GUARD .......................................................................................................................... 18
3.3.13 DISCHARGE LINE MUFFLER ........................................................................................................................ 18
3.3.14 VIBRATION ELIMINATOR .............................................................................................................................. 18
3.3.15 SAFETY VALVE.............................................................................................................................................. 18
3.4 REFRIGERATION SYSTEM ASSEMBLY........................................................................................................... 19
4. CONTROL SYSTEM ............................................................................................................................................. 20
4.1 GENERAL DESCRIPTION .................................................................................................................................. 20
4.2 COOLING CONTROL .......................................................................................................................................... 20
4.2.1 TEMPERATURE SETTINGS ............................................................................................................................ 20
4.2.2 COOLING MODES............................................................................................................................................ 20
4.2.2a LOW COOL .................................................................................................................................................... 21
4.2.2b MEDIUM COOL .............................................................................................................................................. 21
4.2.2c HIGH COOL .................................................................................................................................................... 21
4.3 SUPPLY FAN SPEED CONTROL ....................................................................................................................... 22
4.3.1 GENERAL DESCRIPTION ............................................................................................................................... 22
4.3.2 VARIABLE FREQUENCY DRIVE ..................................................................................................................... 22
4.4 CONTROL PANEL DESCRIPTION & FUNCTION .............................................................................................. 22
4.4.1 MAIN CONTROL PANEL .............................................................................................................................22-24
4.4.2 GENERATOR SET CONTROL PANEL .......................................................................................................24-25
4.4.3 SENSORS....................................................................................................................................................25-26
INDEX

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Contents Page
5. START-UP & SHUTTING DOWN SEQUENCE .................................................................................................... 26
5.1 VISUAL INSPECTION OF EQUIPMENT (CHECK LIST)................................................................................26-27
5.2 STARTING THE GENERATOR ENGINE ............................................................................................................ 28
5.3 STARTING THE ACU (AIR CONDITIONING UNIT) ............................................................................................ 28
5.4 MACHINE SHUT DOWN...................................................................................................................................... 29
6. ALARM AND TROUBLE SHOOTING GUIDE ...................................................................................................... 30
6.1 DESCRIPTION OF ALARM ................................................................................................................................. 30
6.2 TROUBLE SHOOTING GUIDE.......................................................................................................................31-32
7. PROTECTION DEVICES ...................................................................................................................................... 32
7.1 VOLTAGE MONITORING RELAY ....................................................................................................................... 32
7.2 THERMAL OVERLOAD RELAYS........................................................................................................................ 32
7.3 CIRCUIT BREAKERS .......................................................................................................................................... 32
7.4 DISCHARGE PRESSURE SWITCH .................................................................................................................... 32
8. ACCESSORIES ..................................................................................................................................................... 33
8.1 FUEL FILL STATION ASSEMBLY ....................................................................................................................... 33
8.2 SERVICE LAMPS ................................................................................................................................................ 33
8.3 ROTARY (BEACON ) LAMPS.............................................................................................................................. 33
9. MAINTENANCE & SERVICING ........................................................................................................................... 34
9.1 GENERAL MAINTENANCE................................................................................................................................. 34
9.2 INSPECTION & PREVENTIVE MAINTENANCE ............................................................................................34-36
9.3 AIR CONDITIONING SYSTEM ............................................................................................................................ 37
9.4 MOISTURE IN A REFRIGERANT SYSTEM ...................................................................................................38-39
9.5 EVACUATING THE REFRIGERANT SYSTEM ................................................................................................... 40
9.6 REFRIGERANT LEAK TESTING....................................................................................................................40-41
9.7 REFRIGERANT LEAK REPAIR ........................................................................................................................... 41
9.8 REFRIGERANT CHARGING & PRESSURE LIMITS........................................................................................... 42
10. EQUIPMENT DIMENSIONAL DETAILS ............................................................................................................ 43
11. COMPONENT LAYOUT (MAIN CONTROL PANEL) ......................................................................................... 44
12. COMPONENT PARTS LIST (MAIN CONTROL PANEL) .................................................................................. 45
13. PARTS LIST ................................................................................................................................................... 46-51
14. WIRING DIAGRAM ........................................................................................................................................ 52-53
15. SYMBOLS AND LEGENDS ................................................................................................................................ 54
16. PHOTO GALLERY ......................................................................................................................................... 55-66
CONTINUING RESEARCH RESULTS IN STEADY IMPROVEMENTS.
THEREFORE, THESE SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT NOTICE.

3
GENERAL
GENERAL STATEMENT
The Zamil Mobile Air Conditioning units are designed & built for the optimum performance. However, it is required that
you become well acquainted with good practices for the proper installation/operation/and maintenance procedures in
order to ensure a safe trouble free operation, year after year.
Please read through the whole manual contents before you attempt to install/operate/ and maintain the unit.
Most of the procedures described in this manual require certain skills and experience. The installation and other mainte-
nance procedures should be performed only by highly skilled and experienced technicians. The end user’s role should be
limited to the cleaning of the filter.
SAFETY ISSUES
There are three degrees of safety hazards that are identified throughout this manual as WARNING (where the situation
will result in personal injury), CAUTION (where personal injury might occur), and ATTENTION (where minor personal
injury and/or property damage could happen). Please understand and respect those identifications.
WARNING: These units operate on a high voltage with moving parts (at high speed) which can lead to serious
injuries and/or damage to the unit. Never attempt to service the unit unless the main electrical power supply has
been disconnected.
CAUTION: Extra care should be observed when installing, test running, adjusting, servicing, or maintaining the
unit as the hazard of explosion, fire, electrical shock, and potential personal injury and property damage are
present.
Whenperforming any task pertaining tothe installation and maintenance ofthe unit, the skilled technicianshould observe
all the applicable safety measures (wear of safety helmet, boots, gloves, and goggles. Use of proper handling materials
for brazing and use of wet cloth for quenching. A fire extinguisher should be easily accessible etc.). He should also read
all the instructions and information in this Manual prior to attempting to perform any installation or servicing of the unit.
All applicable local codes should also be observed during installation and servicing.

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1. FOREWORD
The purpose of this document is to give a brief description of the MAC240 mobile Air Conditioning equipment, its speci-
fication and other relevant information related to maintenance and safe operation of the equipment.
2. STANDARD SPECIFICATION
The Zamil MAC240 mobile air-conditioning equipment consisting of a dual system refrigeration section (condensing
unit), air handling section, and a power generation unit encased in one complete enclosure. The power generator in the
unit is a diesel fed engine which provides power of 460V-3PH-60HZ to the motors in the equipment. The equipment is
mounted on a trailer for the purpose of movements in any area or at any position proper for its safe operation during
installation.
UNIT LEFT SIDE VIEW
2.1 BASE CHASSIS and CONSTRUCTION
The MAC240 Chassis is ruggedly constructed with mild steel base frame and consists of overall system enclosures as
well as trolley’s components and accessories. The enclosure made of double skin heavy gauge (G-90) zinc coated and
galvanized steel by the hot dip process of lock-forming quality conforming to ASTM A 653 commercial weight G-90
followed by baked on electrostatic polyester dry powder coat. Posts and insulated Aluminum outer panels covered
internally by perforated galvanized steel panels filled with standard fiber glass insulation (25mm thick density: 48 kg/m)
as per NEPA 90A standards. The enclosure is constructed of posts and panels.
The MAC240’s enclosure is provided with inner lighting system in various areas to ease the troubleshooting activities
especially in the emergency cases. In addition, it is designed to have the maximum accessibility using access doors as
well as all the enclosure’s panels and posts are removable incase unusual accessibility is needed.
All the service doors are Hinge mounted with air tight turn buckle lock. These light weight aluminum construction doors
allow easy access to components for service and inspection. The main access doors provided are as follow.

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UNIT TOP VIEW & ACCESS DOOR LOCATION
•Complete back side access is provided with two easy open lockable latched hinged doors to access the power genera-
tor and its components. The first one is to access the genset’s control panel and provided with outer sight glass
allowing quick visual monitoring to genset operation without the need of opening the access door.
•Air Conditioning discharge side access is provide with two easy open lockable latched hinged doors; the first to reach
the cooling system, the fuel injection’s air filter and belts area of power generator’s engine while the other access door
which is provided with outer sight glass allowing quick visual monitoring is the main maintenance access for the whole
system designed to reach the following components/systems:
!The back side of the power generator and its components.
!The A/C system blower and blower motor.
!The variable frequency dive control box control.
•The front side of the MAC240 is provided with one safe hinged door which can be opened by Allen key to prevent
unnecessary opening to the compressor compartment while the system on operation which result safety cutoff to the
compressors due to the high pressure in the condenser side. (refer to the operation part of the manual for more
information).
•The control box side is having only the access door to the control panel user interface and the control box door allowing
the access to all the electrical and control components. While the fuel filling/monitoring is exposed allowing easer
access.
This type of enclosure’s design provides overall system strength as well as reduces the noise level transmitted to the
outer environment from the internal components of the system especially from the power generator side. Moreover, the
components used are enhancing the enclosure noise damping performance like the heavy duty low noise type con-
denser/outer gen-set cooling fans for quieter operation in addition to the Scroll type compressors equipped.
On the other hand, the enclosure is mounted on a heavy duty trolley system and bolted at four points for each side of the
system. This trolley system is consists of rigid steel structure mounted on two heavy duty axles with total four heavy
machinery wheels; each can carry 2.4 tons while the total trolley system is designed to carry up to 8 Tons.

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The trolley system is designed with front turnable axle by means of swivel bearing and both front and rear axles are
mounted on heavy duty leaf springs allowing the required vibration damping to the upper components. This design allows
towing the MAC240 from the front side of the trolley toward the swivel bearing by means of rigid heavy duty beak
supported towing bar as well as it can be lifted by forklift safely. For more towing operation the system is provided with tail
light as well as side reflection lights.
1. Cooling fan
2. V-Belts (fan)
3. Optional attachment of hydraulic pumps
4. V-belt washer
5. Tension roller
6. Oil filler neck
7. Fuel pump
8. Fuel change filter
9. Injection pump
10. Oil dipstick
11. Shut-off magnet
12. SAE housing
13. Lube oil filter
14. Air duct hood
15. Cylinder head cove
2.2 DIESEL ENGINE GENERATOR
The diesel engine generator supplies electrical power to compressors, condenser motor, blower motors and controls
respectively. The generator set mounted across the rear of the unit base. The service accessibility of components is
within easy reach through hinged sight glass doors. The generator is fully self-contained including all controls, alarm
indications, and other operating parameters for the engine and generator. The low emission gas generator set is comply-
ing with international safety protection standards. Exhaust muffler mounted on top of the unit is rigidly connected with
spark arrestor silencer.
A. GENERAL Description:
The power generator used in MAC240 is air cooled “DEUTZ” diesel type which consists of 6-cylinder naturally aspirated
enginesequipped with advanced injection and combustion system, mechanical governor. And connectedto an alternator
to produce 460 Volts 3 phase 60 Hz with a rating of 85.0 KVA running @ NTP (refer to the specification section for more
details). Both the engine and the alternator are controlled by “mecc alte spa” regulator and “DEEP SEA ELECTRONICS”
control system (refer to the components’ appendix and components’ manuals for more information) and located on back
side of the enclosure in top of and to the side alternator respectively.
The power generator of the MAC240 consists of the following components:
It is very important that the riggers and movers should use designated forklift channels
provided under the trolley. MAC unit can be lifted by a minimum 5 ton load forklift vehicle
using proper forklift channels to handle the complete unit weight.

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B. Alternator
This type alternators are brushless, self-regulating and incorporate a rotating inductor with damper cage winding and a
fixed stator with skewed slots. The stator windings have a shortened pitch to reduce the harmonic content of the output
waveform. The alternators are made in compliance with the 98/37, 73/23, 89/336 CEE directives and their amendments,
and the CEI 2-3, EN 60034-1, IEC 34-1, VDE 0530, BS4999-5000, CAN/CSA-C22.2 N°14-95 - N°100-95 regulations.
C. Power Generator Control System:
Thepower generator control system is anAutomatic Mains Failure Control Module. The module is used tomonitor amains
supply and automatically start a standby generator set. The module also provides indication of operational status and fault
conditions, automatically shutting down the genset and indicating failures by means of an LCD display, and appropriate
flashing LED on the front panel.
Selected timers and alarms can be altered by the customer from the front panel. Alterations to the system are made using
the 810 interface and a PC. This interface also provides real time diagnostic facilities.
Easy push-button control
Operation of the module is via push-button controls (with security locking facility) mounted on the front panel with STOP/
RESET, AUTO, MANUAL and START push-button. The first three push-buttons feature LED ‘selected’ indications. Fur-
ther push-buttons provide LCD DISPLAY SCROLL and EVENT LOG VIEW functions.
Microprocessor control
Themodulefeatures16-Bitmicroprocessorcontrol and a comprehensive list of timers and pre-configured sequences. This
allows demanding specifications to be achieved.
Event Log
The instrumentation displays are supplemented further by EVENT LOG VIEW, which shows the last 15 shutdown events
along with date and time of shutdown.
LED indication
‘Hid-‘til-lit’ icons are used to show the presence of alarm conditions detected by the module.
In addition 4 uncommitted LCD segments allow the user to configure the module to provide other status indications from
either internal states or from external digital inputs.
Digital Inputs
The module accepts the following digital inputs:
•Emergency Stop Input - A N/C DC positive input
•Fully configurable warning or shutdown inputs
With the exception of the Emergency Stop Input, these are configurable to be either N/C or N/O contacts connected to the -
Ve DC. The 6 fully configurable auxiliary inputs can be selected to be indication, warning or shutdown inputs either immedi-
ate or held off during start up to allow for use as protection expansion inputs. Alternatively they may be configured to
control extra functions such as Lamp Test or Remote Start input, and many others - refer to appropriate manuals for
details.

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D. Alarms & Shutdowns:

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2.3 UNIT PHYSICAL DATA
MODEL NUMBER MAC240
NOMINAL CAPACITY (TONS) @ 950F AMBIENT 24
CAPACITY (TONS) @ 1150F AMBIENT 21
APPLICATION INDUSTRIAL, 100% FRESH AIR
POWER SUPPLY (V-PH-HZ) 460-3-60
COMPRESSOR Type SCROLL
Part # (Qty.) 800-674-19 (2)
Refrigerant R-22
Operating charge per system, oz 450
RLA/LRA,Amps 19.6/125
CONDENSER FAN & MOTOR Type PROPELLER
Part # (Qty.) 800-226-01 (2)
NominalCFM 15000
Dia. (mm) 700
POWER SUPPLY (V-PH-HZ) 460-3-60
Motor kW - RPM - FLA - LRA 1.5 - 1000- 2.6- 10
EXHAUST FAN Size (mm) 700
Part # (Qty.) 800-237-03 (1)
kW - RPM - FLA - LRA 1.5 - 1000- 2.6- 17.4
MINIMUMCIRCUITAMPACITY Amps 74
MAX. FUSE SIZE/CIRCUIT BREAKER Amps 90
UNIT KVA Amps 54.6
CONDENSER COIL Type Inner grooved tubes and enhanced fins
Tube Dia.- Rows - Fins per inch 3/8-5-14
Total face area (Sq. ft.) 25
EVAPORATORBLOWER Type BACKWARDCURVED
Size (inch) DP/500
Drive type DIRECT DRIVE
NominalCFM 2400
EVAPORATOR BLOWER MOTOR Motor KW 13.2
FLA/LRA 21 /111
Motor frame IEC
EVAPORATORCOIL Type CORRUGATED FIN & TUBE
Tube Dia.- Rows - Fins per inch 1/2-12-10
Total face area (Sq. ft.) 6
HIGH PRESSURE SETTING OPEN - PSIG 450 ± 10
CLOSE - PSIG 360 ± 15
LOW PRESSURE SETTING OPEN - PSIG 25 ± 5
CLOSE - PSIG 50 ± 5
AIR COOLED DIESEL ENGINE GENERATOR / WESTAC ( DEUTZ) WPDZ72/F6L914 (85KVA / 68KW )
UNIT DIMENSIONS TRAILER MOUNTED - L x B x H (meters) 3.6 x 2.2 x 2.6
UNIT WEIGHT ( WITHOUT FUEL), KG 4000
TRAILERSPEEDLIMIT 15 KM / H

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2.3.1 UNIT SPECIFICATION SUMMARY
1. GENERAL
•Length (overall): 141.7 inches (3600mm)
•Width (overall): 86.9 inches (2210 mm)
•Height (overall): 104.5 inches (2654mm)
•Weight (approximate): 8800 lbs (4000 kg)
•Storage Temperature: 40°F to 120°F(clean and dry place)
•Fuel Tank Capacity(approximate): 104 gallons (396 I)
2. POWER GENERATING SYSTEM
•Make: WESTAC (DEUTZ) Air cooled diesel engine generator.
•Model: WPDZ72 (WP07-A76217) / F6L914
•Rating: (85KVA/ 68KW @ NTP)
•Voltage: 460 Volts/ 3 Phase / 60HZ
3. AIR CONDITIONING SYSTEM
•Cooling Capacity: 280,000 BTU/hr. @ 95°F ambient temperature
•Cooling Capacity: 250,000 BTU/hr. @ 115°F ambient temperature
•Ambient Operating Temperatures 50°F to 125°F
•Maximum Humidity: 100%
•Airflow=2156 cfm -100% fresh air
•Static pressure= 20" H2O
•Altitude: To 6561 feet (2000m)
•Refrigerant: R22
4. VEHICLE/ UNIT ENCLOSURE
•Completely self contained enclosure, constructed of base rail, post and double skin aluminum and steel panels. The
whole unit is mounted on heavy duty trolley. All the service doors are hinge mounted with air tight turn buckle lock.
These light weight aluminum construction doors are ready to access component for service and inspection.
•Parking drum brakes in trunnion axle wheel is activated by raising the towing bar and deactivated by lowering the
towing bar.
•Maximum operating trolley speed 15km/ hr

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2.4 AIR CONDITIONING SECTION (ACU)
The factory assembled Air Conditioning unit has cooling or combination of heating (optional) and cooling as a single
package, suitable for mobile applications. The cooling system consists of two stage refrigeration compressors, with each
stage having a closed loop circuit in which the refrigerant is circulated by the pressure differential created by the com-
pressors. The compressor maintains high side condensing pressure and a thermostatic expansion valve separates the
high pressure side from the low pressure side (evaporator). The dual circuit Hermetic scroll compressors run continu-
ously in the ambient temperature of 500C (1220F) at 100% relative humidity environment. Auto refrigeration system
ensures defrost cycle to prevent the system icing.
The unit consists of the following protective devices.
1. High Refrigerant Discharge Pressure Switch
2. Low Suction Pressure Switch
3. Compressor Motor Winding Thermal Overload Protection.
4. Compressor External Overload/ Short Circuit Protection.
5. Blower Motor Overload/ Short Circuit Protection.
6. Condenser Fan Motor Thermal/ Short Circuit Protection
EQUIPMENT EXPLODED VIEW
13
13 EXHAUST FAN
11
07
03
02 SUPPLY AIR OUTLET
04 BLOWER
C5 EVAPORATOR COIL
06 FRESH AIR FILTER
07 FRESH AIR INTAKE PANEL
08 COMPRESSOR
09 CONDENSOR COIL
01 GENERATOR
10 CONDENSOR FAN
11 CONTROL BOX
03 MOTOR
12 EXHAUST MUFFLER - G/SET
02
04
01
12
10
09
08
06
05

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2.5 ELECTRICAL ENCLOSURE ASSEMBLY
The unit has two electrical enclosures, one for the generator engine’s control and the other serves as the unit’s main control
panel. The main unit control panel enclosure is designed with hinged access door and according to NEMA 4 requirements. The
internal power and control wirings are neatly routed and with cable markers for identification as per NEC regulation.
The engine’s control panel has the following monitoring devices:
a) Engine hour meter gauge
b) Engine oil pressure gauge
c) Engine temperature gauge
d) Fuel gauge
e) Coolant level gauge
f) Ammeter
g) Voltmeter
h) Frequency meter
The main unit’s control panel has the following control devices:
a) Unit (engine) start / stop switch
b) Vent / Cool selector switch
c) Cool mode selector switch
d) Panel lamps for unit status indications
e) User interface control board
f) Re-set button
g) Lamp test button
h) Emergency stop push button switch
ELECTRICAL ENCLOSURE
(MAIN CONTROL BOX)

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2.6 OPERATING FROM EXTERNAL POWER SOURCE
The equipment may also be operated from an external power source. The power source rating shall be having a nominal
voltage rating of 460V-3PH-60HZ and can adequately handle the equipment’s power consumption of 55KVA.
When the equipment is operated from an external power source, ensure that the generator’s circuit breaker is switched
“OFF” and the output feeder (power conductors from generator) connected to the main circuit breaker (CB6) in the main
control panel is removed. The power feeder (external power source) can then be fixed on the line terminals of the main
circuit breaker. The equipment can now be operated starting with the steps described in “Start-Up Sequence” 5.3(b) in
this manual.
3. REFRIGERATION SYSTEM
3.1 GENERAL DESCRIPTION
In the basic refrigeration cycle, there are four major components: compressor, condenser, expansion valve and the
evaporator. Let briefly review the function of each of these elements.
The standard unit is equipped with heavy-duty high pressure backward radial fan is capable of supplying required airflow
& static pressure. The fan discharge outlet can be connected to a flexible pre conditioned delivery hose. Flexible duct is
constructed by two-ply, abrasion resistant fabrics or PVC coated fabrics and is stowed inside the unit, when not in use.
Compressor
In the compressor, the low pressure refrigerant vapor is compressed to a high pressure refrigeration vapor. The com-
pressor pumps this refrigerant to the condenser and on through the system.
Condenser
The condenser, receives the high pressure vapor from the compressor, cools it with outdoor air, and then causes the
refrigerant vapor to condense into a high pressure liquid. It may also provide storage for liquid refrigerant in the
system.
Expansion valve
The expansion valve provides a control through which high pressure liquid refrigerant pass into the low pressure side of
the system i.e. evaporator.
Evaporator
The evaporator is a heat exchanger which absorbs heat and boils the low pressure liquid refrigerant, thus changing it into
o low pressure vapor. The low pressure vapor is then drawn back into the compressor and the cycle is repeated.
3.2 REFRIGERATION CYCLE
Whenever the compressor is in operation, there is continuous flow of refrigerant within the system. Liquid refrigerant from
the high pressure side of the system is metered by the expansion valve into the evaporator coil. A portion of the liquid
flashes into vapor resulting in a mixture at the valve outlet. The mixture as it passes through the nozzle orifice of the
distributor rushes with velocity, creating turbulence and thorough mixing. A pressure drop accompanies the mixture as it
passes into the low pressure side of the system. The liquid quickly expands extracting the heat from the air passing the
evaporator coil.
Thesuction action of the compressor draws theheat laden vapor from the evaporator coil. Thepumping of the refrigerant
into the condenser raises its pressure and temperature. Air passing over the condenser surface carries the heat, being
expelled by the refrigerant, away from condenser, thereby lowering the temperature the pressure to allow the heat laden
vapor to be condensed into liquid.
The liquid refrigerant is stored in the condenser where additional heat is sub cooled prior to its passing through the
metering device (expansion valve) into the evaporator coil.

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SCHEMATIC REFRIGERATION DIAGRAM

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3.3 MAJOR REFRIGERATION COMPONENTS
The model MAC240 is equipped with two Copeland hermetic scroll compressor. The compressors have a rated cooling
capacity of 12 tons each and one compressor is used in each refrigerant circuits. Located in the condensing section and
are accessible through front access door. Compressors are conforming to ARI540 STD.
The compressors are equipped with internal motor protection, factory installed crankcase heaters and rubber vibration
isolators for quiet and efficient operation. Each compressor has lock-out devices to protect it from short cycling when
tripped by safety controls. Each compressor has separate condenser coil with safety controls. The diesel generator-set
drives the compressor integral motor.
3.3.1 Scroll Compressor
Scroll working principal is briefly described as below:

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The scroll compressor consists of two involutes or Archimedean spirals. One spiral is positioned inside the other to form
a series of crescent-shaped pockets. During compression the upper spiral remains stationary and the lower one, being
eccentrically mounted on the drive shaft, describes an orbital rather than a simple rotary motion.
How a Scroll Compressor works:
Compression in the scroll is created by the interaction of an orbiting spiral and a stationary
spiral. A refrigerant enters the outer openings as one of the spirals orbits.
The open passages are sealed off as gas is drawn into the spiral.
As the spiral continues to orbit, the gas is compressed into two increasingly smaller pockets.
By the time the gas arrives at the center port, discharge pressure has been reached.
Actually, during operation, all six gas passages are in various stages of compression at all
times, resulting in nearly continuous suction and discharge.

17
Refrigerant enters the compressor at the suction connection and flows around the motor’s housing and enters at the
bottom side through the openings.
Oil droplets separate from the refrigerant and fall into the oil sump.
All suction refrigerant passes through the electrical motor, ensuring full motor cooling.
After that the refrigerant enters the scroll elements.
3.3.2 Condenser Coil
Condenser coils are corrugated fin and tube type; constructed of seamless 3/8" diameter inner grooved copper tubes,
mechanically bonded to enhanced louvered aluminum fins for maximum heat transfer efficiency. As the fins have full self
spacing collars which completely cover each tube. The staggered tube design improves the thermal efficiency. End
plates support sheets are heavy gauge galvanized steel, formed to provide structural strength. Each coil is pressure
tested in the factory at not less than 450 psi air pressure. Finally the coils are coated with thermo guard coating for
protection against seashore salty and corrosive environments.
3.3.3 Condenser Fan
Condenser fans are constructed of die cast aluminum blades/hubs with direct driven motors. All fans are statically and
dynamically balanced to operate at minimum noise and vibration. Fan blades are designed with appropriate pitch angle
which result in maximum airflow through the condenser coil.
3.3.4 Condenser Fan Motor
Condenser fans, the impeller and motors are so constructed to form an integral unit. All fan motors shall be three phase
with class ‘’F’’ winding insulation and ball bearings for high ambient application. These fan motors are of totally enclosed
air over type (TEAO) with inherent thermal protection of automatic reset type & specially designed for outdoor applica-
tions.
3.3.5 Evaporator Coil
Coils are made with corrugated fins and seamless ½’’ diameter copper tubes mechanically bounded enhanced fins
enable maximum heat transfer efficiency. Evaporator is tested in the factory at 300 PSI air pressure. Finally the coils are
coated with thermo guard coating for protection against seashore salty and corrosive environments. Coils conform to ARI
standard 410.
3.3.6 Evaporator Fan
Heavy-duty high pressure backward radial fan is capable of supplying required airflow & static pressure. The fan dis-
charge outlet can be connected to a flexible pre-conditioned delivery hose (supplied along with unit). Flexible duct is
constructed by two-ply, abrasion resistant fabrics or PVC coated fabrics and is stowed inside the storage box, when not
in use.

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3.3.7 Hot Gas By-Pass Control
Hot gas bypass control is provided in the both circuit to permit operation of the system down to 80 % of its unloaded
capacity. Under low ambient condition, it controls temperature by eliminating the need to cycle the compressor on and
off, ensuring narrow temperature swing and lengthen the life span of the compressor.
3.3.8 Crankcase Heater
Each compressor has crankcase heater. The compressor crankcase heater is always on when the compressor is de-
energized. This protects the system against refrigerant migration, oil dilution and potential compressor failure.
3.3.9 Replaceable Core Filter Drier
Refrigerant circuits are kept free of harmful moisture, sludge, acids and oil contaminating particles by the filter drier.
3.3.10 Sight Glass
Moisture indicating sight glass installed in the liquid line. Easy to read color indicator shows moisture contents and
provides a mean for checking the system refrigerant.
3.3.11 Fan Cycle Head Pressure Control
The capacity of air-cooled condensers varies with the difference between condensing temperature and condenser enter-
ing air temperate (ambient temperature). It increases as this difference increases. For a given capacity, a drop in the
ambient temperature will lower the condensing temperatures and if the ambient temperature drops below a given limit,
head pressure control is required. Control shall be set for a minimum of 95°F (35°C) saturated refrigerant condensing
temperature, or to suit the specified application.
3.3.12 Condenser Coil Grills (Guard)
Protect the condenser coil from physical damage.
3.3.13 Discharge Line Mufflers
Discharge line mufflers are installed to eliminate noise due to refrigerant pulsation.
3.3.14 Vibration Eliminator
To eliminate the vibration transmitted from compressor to the piping, unit structure and transportation.
3.3.15 Safety Valve
This valve protects the unit against high discharge pressure in the system due to malfunction of high pressure
switches.

19
01
03
02
08
15
06
05
02 EVAPORATOR COIL
03 CONDENSER COIL
04 EXPANSION VALVE
05 VIBRATION ELIMINATOR
06 HGBP LINE
07 VIBRATION ELIMINATOR
08 MUFFLER
09 BALL VALVE
01 COMPRESSOR
04
07
08
09
3.4 REFRIGERATION SYSTEM ASSEMBLY