1) refrigeration equipment before the installation, should be checked in the box, to see whether the packaging is intact, waterproof, moisture-proof, anti-inversion measures in the transportation process is perfect, to see the box shape with or without damage, to verify that the box number, number of boxes, unit models, accessories and receiving and dispatching units are not incorrect, and so on.
2) When unpacking the box must start from the top of the box, after opening the box, you should first find the packing list attached to the random, one by one, check the box accessories and packing list is consistent.
3) Check whether the model of the unit is consistent with the contract and whether the random documents are complete.
4) Observe whether there is any damage to the appearance of the unit, whether there is any deformation of the pipeline, whether there is any damage to the instrument on the instrument panel, whether the pressure gauge shows pressure, whether there is any damage to the appearance of the valves, accessories, corrosion and so on.
2. Refrigeration unit installation
1) Preparation: Before the unit is installed, the tools and equipment needed for installation should be prepared, such as vacuum pumps, nitrogen cylinders, refrigerant cylinders, U-shaped mercury manometer, leak detector.
2) Checking the installation foundation of the unit: the installation foundation of the unit will be constructed by the civil construction contractor according to the equipment drawings provided by the supplier of the unit, and the foundation should be inspected according to the design requirements before the installation, and the main contents of the inspection include: the external dimensions, the levelness of the foundation plane, the centerline, the marking height and the center distance; whether the attachments in the concrete are in accordance with the design requirements and whether the deviation of the size of the ground bolts is within the specified range. Whether the accessories in the concrete meet the design requirements and whether the deviation of the size of the footing bolts is within the specified range. The appearance of the foundation should not have cracks, honeycomb, holes and so on.
3) After passing the inspection, the horizontal and vertical datum lines for equipment installation are drawn on the foundation according to the requirements of the drawings.
4) Use lifting equipment to lift the unit onto the foundation. Lifting wire rope should be located in the condenser or evaporator cylinder support outside, and be careful not to let the wire rope touch the dashboard and other vulnerable parts, and in the wire rope and the unit contact point on the pad on the wooden board.
5) unit alignment: in the lifting equipment will be set in place after the unit, to check the unit's horizontal and vertical centerline and the centerline of the foundation is correct, if not, can be corrected with pry bars and other equipment.
6) leveling: after the equipment is in place, the level is placed on the flange surface of the compressor air inlet and exhaust port of the unit, and the unit is leveled, and the horizontal and vertical level of the unit is required to be less than 1/1000, and the unevenness can be leveled with a flat gasket.
7) the installation of the unit water system: the unit cooling water import and export should be installed soft joints, each inlet and outlet pipe should be added regulating valves, thermometers, pressure gauges; in the unit refrigerant water and cooling water pipeline should be installed filters; water piping system should be set up to bleed air at the highest point of the pipe.
8) The installation of the electrical system of the unit should be noted, before the installation of the single device debugging, so that it meets the requirements of the regulation.
9) Instrumentation and electrical equipment should be connected to the wire number, and firmly connected to the terminal, neatly arranged.
3. Refrigeration system connection
1) Before connecting the pipeline, the nitrogen gas in the unit should be drained.
2) Use the refrigeration system special, clean and treated copper pipe.
3) Requirements for horizontal piping in the system should be downward sloping in the direction of refrigerant liquid flow (0.01?0. 025).
4) refrigerator evaporator installation position higher than the compressor, the height difference in 5m or less, and in the evaporator back to the outlet set U-shaped return bend, the radius of the return bend should be as small as possible, the return pipe should be higher than the upper plane of the evaporator and then connected to the suction riser.
5) When the installation position of evaporator is lower than the compressor, the oil return bend should be set at the bottom of the air return riser, if the height difference is more than 5m, an oil return bend should be set every 5m, and the total height difference is more than 20m.
6) The support of refrigeration pipeline in the cold storage room should be fixed firmly, to avoid the formation of lubricating oil traps in pipeline due to the sagging of the pipeline.
7) The return air pipeline of refrigeration should be insulated to reduce the loss of cold and avoid excessive harmful overheating.
8) After completing the connection between the unit and the pipeline, the pressure leakage detection method should be applied to the whole system including the refrigeration unit, condenser, evaporator, all kinds of valves and pipelines to carry out leakage detection and leakage test under pressure to confirm that the whole refrigeration system is free from leakage.
4. unit leakage test operational requirements
Small cold storage refrigeration system installation is completed, must be carried out after the pressure test and vacuum test. Refrigeration system pressure test is divided into high and low pressure two steps. The steps are as follows:
1) in the high and low pressure part of the pressure gauge, remove the original system is not suitable to withstand high pressure components and valves (such as evaporation pressure regulator valve, pressure controller, thermal expansion valve, etc.), and other valves or piping instead of opening the pipeline of all other valves.
2) from any high-pressure system to the whole system filled with nitrogen, and make the pressure to reach the low-pressure test gauge pressure (R12 about l.OMPa, R22 about 1.4MPa) that is to stop filling nitrogen.
3) Observe the system pressure drop. If the pressure drop is obvious, the application of soap solution to find leaks.
4) low-pressure test is completed, that is, the high-pressure system pressure test. At this time, close the compressor discharge valve and expansion valve before the liquid supply shut-off valve, continue to high-pressure system filled with nitrogen, so that the pressure is increased to high-pressure test pressure (R12 about 1.6 MPa, R22 about 2.0 MPa) and stop filling nitrogen, and to observe the high-pressure system pressure drop and again looking for leaks.
5) refrigeration system pressure 24?48h. The first 4h pressure drop table pressure does not exceed 0.03MPa, and then continued to stabilize (test process, due to temperature changes in the pressure rise and fall generally does not exceed the table pressure of 0.01?0.03MPa), that is, the test is qualified.
6) vacuum test of the refrigeration system, must use a vacuum pump. Vacuum pumping, first open all the connected valves on the system, close the valve connected with the atmosphere, and then use the pressure-resistant rubber hose to connect the suction port of the vacuum pump with the refrigerant charging valve of the refrigeration system, start the vacuum pump, the air in the system by the vacuum pump exhaust port discharge, when the vacuum degree is more than 0.093 MPa, close the refrigerant charging valve, stop the pump and check whether the system is leaking.
7) Refrigeration system refrigerant charging leakage test. Refrigeration system after blowing, pressure test and vacuum test all meet the requirements, you can use the system vacuum directly to the system refrigerant charging, the method is: one end of the fluoride tube and Freon cylinder bottle valve connected, the other end of the refrigerant charging valve with the refrigeration system virtual connection, open the Freon cylinder bottle valve, see the refrigerant charging valve mouth of the refrigeration system refrigerant white smoke-like aerosol of refrigerant, quickly tighten the interface, the refrigerant system into the gaseous refrigerant, the refrigerant system. Charge gaseous refrigerant into the refrigeration system. When the pressure in the system rises to 0.3MPa, close the bottle valve, stop charging refrigerant vapor to the system, and then use phenolphthalein chemical test paper or halogen leakage detection lamp for leakage detection.
In the process of leakage detection, if you find that the pressure has dropped, but in the system and can not find the leakage, then you should pay attention to the following possibilities:
1) condenser refrigerant side of the water side of the leakage, you should open the water side of the two ends of the cover for inspection.
2) If the system is used for many years to overhaul, you should pay attention to the low-pressure piping wrapped in insulation inside the joints for leaks.
3) Various automatic regulating equipment and components may also produce leaks, such as pressure controller bellows.
5. unit vacuum operation requirements
1) for the newly installed unit, must use the vacuum pump to vacuum the entire refrigeration system. It is not allowed to use the compressor of the unit to evacuate the system, otherwise it may cause irreparable damage to the compressor.
2) vacuum should be the entire refrigeration system of all the valves open, from the refrigeration system on both sides of the high and low pressure at the same time for vacuum, in the case of technical conditions allow, you can use the vacuum pressure gauge to detect the degree of vacuum. Requirements for vacuum refers to the standard should reach below 30Pa.
6. unit refrigerant charging operation requirements
1) to the unit refrigeration system refrigerant charging work procedures, should be in the refrigeration system after the end of the vacuum immediately after the refrigerant charging operation, in order to prevent due to the system's internal vacuum, resulting in the infiltration of air.
2) Before charging refrigerant to the refrigeration system of the unit, the circuit of the solenoid valve in the system should be turned on so that it is in the open state. The first charge of refrigerant should be made from the liquid filling port of the high-pressure valve section of the unit, with liquid refrigerant. A filter drier should be installed on the liquid filling pipe between the unit and the Freon cylinder to prevent moisture and impurities in the refrigerant from entering the system.
3) The first charge of refrigerant can be 80% of the rated value of the demand of the refrigeration system, and the first charge should not be too much.
4) After the refilling is completed, stand still for about 30min, when the unit refrigeration system internal pressure is stabilized, the compressor can be started, (for water-cooled units, the cooling water system should be turned on first) to observe the refrigerant operation status, generally can be observed from the system in the liquid-viewing mirror of the flow state of the refrigerant to determine the appropriate amount of refrigerant charging, if there is insufficient refrigerant, can be from the low-pressure detection port to the amount of gaseous refrigerant filling, until the first filling amount should not be too much. Refill gaseous refrigerant, until the visual liquid mirror bubble disappears, the evaporator is full of uniform frost, the compressor return tube full of dew, you can determine the refrigeration system is suitable for refilling refrigerant.