1、McQuay is participating in the Eurovent Certification Programme. Product are as listed in the Eurovent Directory of Certified Products and on the web site www.eurovent- Installation, Operation and Maintenance manual 803 C 05/10 B Date: October 2005 Supersedes: 803 C 04/06 A !“#$% both must be blown
2、out to help avoid damage from freezing. The piping should also include thermometers at the inlet and outlet connections and air vents at the high points. The water heads can be interchanged (end for end) so that the water connections can be made at either end of the unit. If this is done, new head g
3、askets must be used and control sensors relocated. In cases where the water pump noise can be objectionable, vibration isolation sections are recommended at both the inlet and outlet of the pump. In most cases, it will not be necessary to provide vibration eliminator sections in the condenser inlet
4、and outlet water lines. But they can be required where noise and vibration are critical. Cooling tower If cooling tower is used, a balancing valve is recommended. Some form of temperature control is also required if cooling tower water should be very cold. Unit microprocessor includes the control fo
5、r cooling tower fans. Therefore it is suggested to make the relevant wiring connections. Water treatment Before every start-up, clean and flush the cooling water circuit. Make sure tower blowdown or bleed-off is operating. It should be recognized that atmospheric air contains many contaminants that
6、increase the need for proper water treatment. The use of untreated water can result in corrosion, erosion, sliming, scaling or algae formation. McQuay Italia S.p.A. assumes no responsibility for the results of untreated or improperly treated water. Flow direction marked on switch I in. (25mm) NPT fl
7、ow switch connection Tee 803 C 05/10 B pag. 6/30 Glycol solution CAUTION Use exclusively glycol for industrial applications. Do not use antifreeze for automotive applications (this kind of antifreeze contains inhibitors that cause the evaporator tubes plating). Type and managing of the glycol have t
8、o be according to rules in force. Temperature and water flow limits Operating Range0102030405060-10 -5 0 5 10 15 20Evaporator leaving temperature - CCondenserleavingtemperature-CNote: the use of glycol is necessary for evaporator leaving water temperature below +3C. Flow rates below the minimum valu
9、es shown in the evaporator and condenser pressure drop curves, may cause freeze-up problems, scaling and poor control. Flow rates above the maximum values shown in the evaporator and condenser pressure drop curves will result in unacceptable pressure drops, excessive erosion and tube vibrations pote
10、ntial cause of tubes failure. Evaporator freeze protection 1. If the unit will not operate during the winter, drain and flush the evaporator and chilled water piping with glycol. Drain and vent connections are provided on the evaporator. 2. Insulate the water pipes, especially the chilled water side
11、. Note: freeze damages are not considered warranty failures. McQuay Italia S.p.A. declines any liability. 803 C 05/10 B pag. 7/30 Condenser protection and design considerations When the unit is not operating, the condenser temperature and the liquid refrigerant line can go down the room temperature
12、if the cooling fluid comes from lake, river or bed water and the water valves have a blow-by. This problem occurs when cold water circulates inside the condenser and the unit is off waiting to be loaded. Under these conditions: 1. Shut-off the condenser water pump when the compressor is off. 2. Veri
13、fy the liquid line solenoid valve is operating properly. Chilled water temperature sensor The PFS water-cooled chiller is equipped with a microprocessor. Be careful when working around the unit to avoid damaging cables and sensors. Check the cables before running the unit. Avoid rubbing the cables o
14、n the frame or other components. Verify the cables are firmly anchored. If the temperature sensor is removed from the well for servicing, do not wipe off the heat conducting compound supplied in the well and place the sensor correctly. Safety valves Each system will be equipped with a safety valve o
15、n condenser and evaporator in order to release the refrigerant charge in case of faulty operation. Most codes require that relief valves be vented to the outside, and this is a desirable practice for all installations. CAUTION To prevent injuries for R134a inhalation, avoid releasing the refrigerant
16、 in the atmosphere or inside. The relief valves have to be vented to the outside, according to the rules in force in the country of the installation. The installer is responsible for sizing the bleeder pipes and connecting the relief valves to them. Electrical connections Wire size must be in accord
17、ance with the nameplate data and the rules in force. McQuay Italia S.p.A. assumes no responsibility for the results of improperly electrical connections. CAUTION Connections to terminals must be made with copper lugs and copper wire. Qualified and licensed electricians must perform wiring. Shock haz
18、ard exists. Power wiring to compressors must be in proper phase sequence. For this reason, phase monitor is supplied as standard. Voltage unbalance Extreme voltage unbalance in a three-phase system is the cause of increase in motor temperature. The voltage unbalance between phases must not exceed 2%
19、, according to the following calculation. unbalance % = (Vx-Vm) x 100 Vm Vx= phase with the maximum unbalance Vm= avarage voltage 803 C 05/10 B pag. 8/30 i.e. the three phases are 383V, 386V e 392V, the average is: 383+386+392 = 387V, 3 therefore unbalance % is: (392-387)x100 = 1,29% less then the m
20、aximum allowed (2%) 387 Control circuit McQuay PFS units circuit control is supplied with 110 Vac power. Move the ON/OFF switch controller (Q0) to the “off” position every time unit operation is not required. Inside the controller are installed connecting terminals for the water flow lock. See the w
21、iring diagram to operate the correct connection on the field. The purpose of the water flow interlocked switch is avoiding the compressor operation till the evaporator and condenser pumps are able to grant the correct water flow. The flow switch or the differential pressure switch is an accessory su
22、pplied by McQuay Italia upon request however necessary to be installed on the unit. It is recommended to let the microprocessor controlling the pumps for a better plant system. In case of external control on the pumps use the following procedure. Evaporator water pump: start-up the pump 2 minutes be
23、fore turn on the unit; switch off the pump 5 minutes after turn off the unit. Condenser water pump: start the pump 30 seconds before turn on the unit; switch on the pump 1 minute after the last compressor is off. When the unit is not operating the condenser pump must be always off. Circuit control t
24、est All PFS units are factory tested. Both the control and power circuits are carefully inspected before delivering. Operation Operator responsibilities It is important that the operator become familiar with the equipment and the system before attempting to operate the chiller. In addition to readin
25、g this manual, the operator should study the operation manual for the controller and the wiring diagram furnished with the unit before starting, operating, or shutting it down. During the initial startup of the chiller the McQuay technician will be available to answer any questions and instruct in t
26、he proper operating procedures. It is recommended that the operator maintain an operating log for each individual chiller unit. In addition, a separate maintenance log should be kept of the periodic maintenance and servicing activities. This McQuay chiller represents a substantial investment and des
27、erves the attention and care normally given to keep this equipment in good working order. If the operator encounters abnormal or unusual operating conditions, it is recommended that a McQuay service technician be consulted. 803 C 05/10 B pag. 9/30 Nomenclature P F S “B” 249 . 2 134 P Water cooled F
28、Flooded S Screw compressor “B” Release 103296 Unit size 1 N of compressors 2 134 Refrigerant HFC 134a803 C 05/10 B pag. 10/30 Unit Description Unit is equipped with Fr4 series single screw compressor and it includes a flooded shell-and-tube evaporator with the refrigerant out the high efficiency tub
29、es and the water inside them, a shell-and-tube type condenser operating with the refrigerant out the high efficiency tubes and the cooling water inside them. The single semi-hermetic screw compressor uses the suction gas coming from the evaporator to chill the motor and to allow an excellent operati
30、on of the unit in all working load conditions. Besides the standard lubrication of the moving parts, the oil injection lubrication system allows the sealing of the screw granting the gas compression. The refrigerant circuit also installs a rolling valve with a mechanical pilot system that runs the r
31、efrigerant levels inside the heat exchangers still controlling the PUMP-DOWN operation. All the reported components are managed by an innovative microprocessor control system able to monitor all operating parameters optimising the process. A self-diagnostic system helps the operator to detect the al
32、arm and the failure cause. Refrigerant Cycle Description The low temperature refrigerant gas coming from the evaporator to the compressor cools the electric motor. Later it is compressed and during this phase the refrigerant is mixed up to the oil coming from the separator. The high-pressure oil ref
33、rigerant mixture is conveyed inside the oil separator of centrifugal high efficiency type. Oil sediment to the end plate separator due to the pressure difference is again conveyed to the compressor while the refrigerant separated from the oil is delivered to the condenser. Inside the condenser the l
34、iquid refrigerant is equally distributed on all tube bundle surface. Crossing the heat exchangers tubes, the refrigerant desuperheats starting to condense. Desuperheating and condensing heat is taken off from condensing water consequently increasing the temperature. Liquid condensed at saturation te
35、mperature crosses the subcooling section still yielding heat, which increases the cycle efficiency. The subcooled liquid crosses the rolling gear that by a pressure drop starts an expansion process flashing a part of the refrigerant. The result is a low pressure and temperature liquid and gas mixtur
36、e heat sensible that is conveyed to the evaporator. The liquid-gas refrigerant after being equally distributed along the tube bundle, exchanges the heat with the water to be chilled reducing the temperature until the complete evaporation. At gas condition the refrigerant leaves the evaporator to be
37、again aspired by the compressor starting a new cycle. Evaporator The evaporator is flooded shell-and-tube with the refrigerant out the tubes and the water inside them. Normally no maintenance and service operation is required. When it is necessary to replace a tube it is easy to remove the old one.
38、Condenser The condenser is shell-and-tube with the refrigerant out the tubes and the water inside them. The condenser tubes are externally finned and expanded on the tube plate. All units have an integrated subcooling in the condenser also equipped with a safety valve. If required it is possible to
39、remove and replace the tubes. Expansion valve The expansion valve is directly controlled by a refrigerant level sensor placed on the condenser. The system controls the refrigerant liquid level, to grant an adequate operation of the expansion valve, completely flooding the integrated sub-cooling sect
40、ion of the shell-and-tube condenser. A solenoid valve controlled by the microprocessor is installed on the expansion valve body. It allows the automatic control of pump-down function and the valve opening during the shutdown period. The adequate positioning of liquid sensor and an appropriate refrig
41、erant charge (factory executed) allow an efficient and reliable unit operation. Clear refrigerant sight glasses are located on the condenser and evaporator shells to verify immediately the adequate charge. 803 C 05/10 B pag. 11/30 Refrigerant level sensor The level sensor includes a floating element
42、 checking the refrigerant level inside the condenser and controlling the expansion valve indirectly monitoring the refrigerant flow. A regulating valve, installed on the sensor flange, allows to level stabilizing. This valve is factory set during the test and normally does not require any further ad
43、justment on the field unless on particularly unstable plant where an additional regulation must be operated from qualified personnel only. Compressors The compressor is controlled by a special motor, installed on the end of the main driving shaft. It consists of two screwed cast iron element: the ma
44、in one includes all moving parts as the main rotor and the two satellites, the second element includes the three-phases 2-poles electric motor. The gas flows through the electric motor, cooling the windings before entering the suction ports. Sensors inside the windings motor constantly monitor the t
45、emperature preventing from dangerous overheating. A terminal box including the connectors for thermistors and power lines is located up to the motor casing. The compressor moving elements executing the compression include 3 rotating parts, there are neither reciprocating nor eccentric motions inside
46、 the compressor. Basic elements are the main rotor and two exactly opposed gate rotors tightly meshing each other. A specially shaped synthetic material placed between the main rotor and the satellites executes tightness seal during the compression. The main shaft fixing both the motor and the main
47、rotor is supported by 3 ball bearings. This system is balanced both statically and dynamically before the assembly. Two large closing flanges are also installed on the compressor sides for an easy access to the satellites, rotor, shaft and bearings without influencing the assembly tolerances. Compre
48、ssion process With the single-screw compressor the refrigerant suction, compression and discharge process is operated by a continue flow for each satellite. During this operation the volume is progressively reduced compressing the refrigerant. After the compression, the gas is discharged through the
49、 ports properly designed. See figure 3 for suction, compression and discharge cycle. 803 C 05/10 B pag. 12/30 1. 2. 3. 4. Figure 3, Compression Process c A a b B c a b A B a b A B a b c Suction Gas Discharge Gas 1. and 2. Suction Main rotor flutes a, b and c are in communication at one end with the suction chamber via the bevelled rotor end face, and are sealed at the other end by the teeth of star rotor A. As
