First, the unpacking check before installation

1. Before installing the refrigeration equipment, check the packaging box to see if the packaging is intact. Whether the waterproof, moisture-proof and anti-inverting measures are perfect during transportation, check the shape of the box for damage, verify the box number, the number of boxes, and the unit. The model, accessories and transceiver units are correct.

2. When unpacking the package, it must start from the top of the box. After opening the package, you should first find the packing list attached, and check whether the accessories in the box match the packing list one by one.

3. Check if the unit model is consistent with the contract and whether the random files are complete.

4. Observe the appearance of the unit for damage, whether the pipeline is deformed, whether the instrument on the instrument panel is damaged, whether the pressure gauge shows pressure, whether the appearance of each valve or accessory is damaged or rusted.

Second, refrigeration unit installation

1. Preparation: Before the unit is installed, the tools and equipment required for installation, such as vacuum pump, nitrogen bottle, refrigerant cylinder, U-shaped mercury pressure gauge, leak detector, etc., should be prepared.

2. Check the installation base of the unit: The installation base of the unit shall be constructed by the civil construction party according to the equipment drawings provided by the unit supplier. The foundation shall be inspected according to the design requirements before installation. The main inspection contents include: the dimensions of the unit and the level of the foundation plane. Degree, centerline, standard and center distance; whether the accessories in the concrete meet the design requirements and the dimensional deviation of the anchor bolts is within the specified range. The appearance of the foundation is required to be free of cracks, honeycombs, voids, and the like.

3. After passing the inspection, draw the horizontal and vertical reference lines for equipment installation on the basis of the drawings.

4. Lift the unit to the foundation with lifting equipment. The hoisted wire rope should be placed outside the cylinder support of the condenser or evaporator, and be careful not to let the wire rope hit the vulnerable parts such as the instrument panel, and put the wood board on the contact point between the wire rope and the unit.

5. The unit is correct: After the unit is in place with the lifting equipment, it is necessary to check whether the horizontal and vertical center lines of the unit are aligned with the center line on the foundation. If not, the equipment such as the crowbar can be used for correction.

6. Leveling: After the equipment is in place, use the level meter on the end face of the inlet and outlet of the unit compressor to level the unit. The horizontal and horizontal levels of the unit are required to be less than 1/1000. The horn is leveled.

7. Installation of the unit water system: soft joints should be installed at the inlet and outlet of the unit cooling water. Regulators, thermometers and pressure gauges should be added to each inlet and outlet pipe; filters should be installed on the unit's refrigerant water and cooling water pipes; Air pipes should be placed at the place.

8. The installation of the electrical system of the unit should be noted that the single equipment should be commissioned before installation to meet the adjustment requirements.

9. The connecting wires of the instrument and electrical equipment should be marked with the wire number and firmly connected with the terminal block, neatly arranged.

Third, the refrigeration system connection

1. The nitrogen in the unit should be drained clean before the pipeline is connected.

2. Use a clean copper tube for the refrigeration system.

3. The horizontal pipe in the system should be inclined downward (0.01~0. 025) along the flow direction of the refrigerant liquid.

4. When the installation position of the refrigerator evaporator is higher than the compressor, the height difference is within 5m, and a U-shaped oil return bend is set at the outlet of the evaporator return port. The radius of the oil return bend should be as small as possible, and the return pipe should be higher than the evaporator. The upper plane is then connected to the suction riser.

5. When the installation position of the refrigerator evaporator is lower than that of the compressor, the oil return bend should be set at the bottom of the return air riser. If the height difference is greater than 5m, a return oil bend should be set every 5m, and the total height difference is greater than 20m. .

6. The refrigeration pipeline support of the refrigerator should be firmly fixed to avoid the formation of lubricating oil traps in the pipeline due to the drooping of the pipeline.

7. The return air piping of the refrigeration should adopt heat insulation measures to reduce the loss of cooling capacity and avoid excessive harmful overheating.

8. After completing the connection between the unit and the pipeline, apply the pressure leak detection method to perform leak detection and pressure proof leak detection on the entire system including the refrigeration unit, condenser, evaporator, various valve parts and piping to confirm There is no leakage in the entire refrigeration system.

Fourth, the unit leak detection operation requirements

After the installation of the small refrigerator refrigeration system, pressure test and vacuum test must be carried out. The pressure test of the refrigeration system is carried out in two steps: high and low pressure. The steps are as follows:

1. Connect the pressure gauge to the high and low pressure parts, remove the parts and valve parts (such as evaporative pressure regulating valve, pressure controller, thermal expansion valve, etc.) that are not suitable for excessive pressure in the original system, and replace them with other valves or pipes. Open all other valves on the line.

2. Fill the whole system with nitrogen from any part of the high pressure system, and let the pressure reach the pressure of the low pressure test meter (R12 is about 1.0MPa, R22 is about 1.4MPa), then stop filling with nitrogen.

3. Observe the system pressure drop. If the pressure drop is significant, use soapy liquid to find the leak.

4. After the low pressure test is completed, the pressure test of the high pressure system is performed. At this time, close the compressor discharge valve and the liquid supply shut-off valve before the expansion valve, continue to charge the high-pressure system with nitrogen, and increase the pressure to the high-pressure test gauge pressure (R12 about 1.6 MPa, R22 is about 2.0 MPa), then stop filling with nitrogen. Observe the pressure drop of the high pressure system and find the leak again.

5. The refrigeration system is kept at 24~48h. The pressure of the first 4h pressure drop gauge does not exceed 0.03MPa, and then continues to be stable (in the test process, the pressure rises and falls due to the temperature change generally does not exceed the gauge pressure 0.01~0.03MPa), that is, the test is qualified.

6. Vacuum test of refrigeration system, vacuum pump must be used. Vacuuming with a vacuum pump, first open all connected valves on the system, close the valve that is open to the atmosphere, and then connect the suction port of the vacuum pump to the refrigerant charging valve of the refrigeration system with a pressure-resistant rubber tube to start the vacuum pump. The air in the system is vacuum pump. The exhaust port is exhausted. When the vacuum exceeds 0.093 MPa, the refrigerant charging valve is closed, the pump is stopped, and the system is checked for leaks.

7. The refrigerant charging test of the refrigeration system. After the refrigeration system has reached the requirements through the blowdown, pressure test and vacuum test, the system vacuum can be used to directly charge the system with refrigerant.

The method is: one end of the fluorinated tube is connected with the bottle valve of the freon cylinder, the other end is connected with the refrigerant charging valve of the refrigeration system, and the freon cylinder valve is opened, and the refrigerant charging valve port of the refrigeration system is white. In the case of a misty refrigerant mist, quickly tighten the interface to inject gaseous refrigerant into the refrigeration system. When the pressure in the system rises to 0.3 MPa, close the bottle valve, stop charging the system with refrigerant vapor, and then use a phenolphthalein chemical test paper or a halogen leak detector for leak detection.

If the pressure is found to decrease during the leak detection process, but the leak cannot be found in the system, the following possibilities should be noted:

1. The refrigerant side of the condenser leaks to the water side, and the water should be opened at both ends to cover.

2. If the system is overhauled for many years, you should pay attention to whether the low-pressure pipeline is leaking at the joint inside the heat-insulating material.

3, various automatic adjustment equipment and components may also produce leakage, such as the bellows of the pressure controller.

V. Unit vacuuming operation requirements

1. For newly installed units, the entire refrigeration system must be evacuated using a vacuum pump. Do not use the compressor of this unit to evacuate the system, otherwise it may cause irreparable damage to the compressor.

2. When vacuuming, all valves of the whole refrigeration system should be opened, and vacuum should be simultaneously applied from both sides of the refrigeration system. Under the condition of technical conditions, a vacuum pressure gauge can be used to detect the degree of vacuuming. The required vacuum degree means that the standard should reach 30 Pa or less.

Sixth, the unit fills the refrigerant operation requirements

1. The working procedure for adding refrigerant to the refrigeration system of the unit should be carried out immediately after the end of the vacuum system to prevent the air from penetrating due to the internal vacuum of the system.

2. Before adding refrigerant to the unit refrigeration system, the circuit of the solenoid valve in the system should be turned on to make it open. For the first time, the refrigerant should be filled with liquid refrigerant from the filling port of the high pressure valve section of the unit. A dry filter should be installed on the dosing tube between the unit and the Freon cylinder to prevent moisture and impurities from entraining the refrigerant from entering the system.

3. The first filling amount of the refrigerant can be added according to 80% of the rated value of the refrigeration system. The first filling amount should not be too much.

4. After the filling is completed, it will be static for about 30 minutes. After the internal pressure of the standby group refrigeration system is stable, the compressor can be started. (For the water-cooled unit, the cooling water system should be turned on first) to observe the operating state of the refrigerant, generally from the system. Observe the flow state of the refrigerant in the liquid mirror to judge whether the refrigerant charge is appropriate. If the refrigerant is insufficient, a proper amount of gas refrigerant can be added from the low pressure detection port until the bubble disappears in the sight glass, and the evaporator is evenly filled. The frost, the compressor return pipe is covered with dew, it can be determined that the refrigeration system is filled with refrigerant.