User manual TECUMSEH ROTARY COMPRESSORS RG

[. . . ] MANUAL INSTALLATION AND OPERATION Rotary Compressors RK, RG and HG 1 General Information 1. 1 1. 2 1. 3 1. 4 The working principle of the Rotary Compressor Range Performance Voltage and range of operation 1. 4. 1 1. 4. 2 1. 5 1. 6 1. 7 Single phase Three phase 5 5 6 7 7 7 7 8 8 8 Dimensions and connections Mountings Oil type 2 Operating Range 2. 1 2. 2 2. 3 Operating envelope Operating compression ratio Operating pressure differential 9 9 9 9 3 Temperature Criteria 3. 1 3. 2 3. 3 3. 4 Ambient temperature Discharge temperature Motor temperature Return gas temperature 10 10 10 10 10 4 General Recommendations 4. 1 4. 2 System requirements Pipework design 4. 2. 1 4. 2. 2 4. 2. 3 4. 2. 4 4. 2. 5 4. 3 4. 3. 1 4. 3. 2 2 11 11 11 11 14 14 14 16 21 21 21 21 21 21 Pipework design advice/guidance Connections Flexible connections Velocity within pipework and heat exchangers Capillaries Advice for installers Refrigerant charge Frequency of starts Start-up pressure Refrigerant charge 4. 4 Starting 4. 4. 1 4. 4. 2 4 General Recommendations (continued) 4. 5 4. 6 Liquid return whilst operating Liquid migration during prolonged shutdown 4. 6. 1 4. 6. 2 4. 7 Band heaters Non-return valves 22 22 22 22 22 Purging refrigerant from the system 5 Security 5. 1 5. 2 5. 3 Pressure Electrical Declaration of incorporation 23 23 23 23 6 Appendices 6. 1 6. 2 Documents Contacts 25 25 25 3 Tecumseh Europe with its long experience of compressor development has introduced a range of rotary compressors for air conditioning and commercial refrigeration. This operating manual has been designed to help you correctly install this compressor range in your applications. 1 1. 1 General Information The working principle of the Rotary Compressor 1 | Names of the different pieces 2 | End of suction and the start of compression 3 | Start of compression and suction 4 | Compression and suction 5 | Compressed gas exit Rotary compressors are `high pressure shell' type compressors. The suction on these compressors is taken directly into the compression chamber. Gas compressed in the compression chamber is discharged into the compressor casing. [. . . ] To ensure the expansion device functions correctly, the pressure of the liquid reaching it must be sufficiently high, and preferably, slightly subcooled. It is essential to restrict the pressure drop in the pipework for the following reasons: > To prevent a reduction in the mass flow through the expansion device, > To prevent partial vaporization of the liquid refrigerant prior to the expansion device (pressure drop higher than subcooling). The components fitted to the liquid line such as the filter drier, solenoid valve, liquid line sight glass also cause varying pressure drops. The pressure drop in this pipework must not exceed 0. 5°C. 4. 2. 1. 1. 3 Positioning of accessories on the liquid line The diagrams below show the normal position of accessories on the liquid line. The filter drier must be positioned next to the expansion device to prevent clogging by impurities. It should be installed in a vertical position with the outlet downwards to ensure constant liquid supply to the expansion device. The liquid sight glass should be positioned between the drier and the expansion device in order to indicate that: Liquid line - position of accessories > Liquid / vapour is present, > The level of risedual humidity. 13 4. 2. 2 Connections The rotary compressors have copper connections. Please note the following: · Brazing should be carried out using an inert gas (Nitrogen). · Protect paintwork while brazing by covering the accumulator and compressor with a damp cloth. · Brazing of the connections must comply with the recommendations of the Standard NF EN 378-2. · Carry out pipe cutting and bending operations carefully in order to prevent dust and swarf contaminating the system. Care should be taken to ensure that flux does not contaminate the system. 4. 2. 3 Flexible connections Rotary compressors do not have internal mounting springs, in contrast to the majority of hermetic compressors. The internal design and external mountings are designed to reduce vibration. However, some vibration is transmitted to the suction and discharge pipework. We therefore recommend using flexible connections to prevent vibration being transmitted to the rest of the installation. A suggested design of flexible connections for this range of compressors and their applications is shown in the diagrams in the Appendices (see p. The general design of the pipework can be adjusted according to your equipment. The recommended suction loop of 3/8 inch and 1/4 inch discharge should be adhered too. Great care should be taken when designing the system and correct refrigeration practices must be followed to ensure the oil return to the compressor. 4. 2. 4 Velocity within pipework and heat exchangers To ensure correct running of the installation and to assure the working life of the compressor, it is recommended that pipework be calculated using the velocities shown in the table below. SUCTION Connections Anti-vibration loops Pipework Evaporator Condenser 4 m/s 3 m/s Minimum Maximum 25 m/s 15 m/s 8 m/s DISCHARGE Minimum Maximum 25 m/s 4 m/s 15 m/s LIQUID Minimum Maximum 0. 3 m/s 1 m/s 3 m/s 10 m/s Anti-vibration loops are used to provide a very flexible pipework system which absorbs vibration. The velocity in the AV loops should not exceed that stated in the table. A minimum velocity of 8 m/s is necessary in any vertical risers, suction or discharge to ensure adequate oil return to the compressor. The velocity within the heat exchangers should not drop below 3 m/s to guarantee oil return. [. . . ] When charging do not use the temperature of the compressor shell as a guideline for a full charge. High pressure shell compressors take longer to reach normal operating pressure when starting from cold than low pressure shell compressors. This is due to the additional volume of the compressor casing and refrigerant being entrained in the oil. Condensing pressure will only reach the operating level if the entrained refrigerant evaporates completely. 4. 4 Starting Never switch on a compressor when under vacuum, an electric arc can occur inside the compressor. 4. 4. 1 Frequency of starts Under no circumstances should 10-12 starts per hour be exceeded. [. . . ]