Requirements for adding refrigerant to industrial chiller system
The industrial cooling system has passed the vacuum test, and the vacuum state in the system can be used for refrigerant charging.
1. Refrigerant charge
For newly installed systems, refrigerant can be added to the high-pressure side, the operation method is as follows:
1) Open the cooling water system of the condenser and keep the valves in the system the same as during the vacuum test
2) Connect the steel cylinder containing the refrigerant to the West 14mm×2mm seamless steel pipe (use copper pipe when adding fluorine). The mouth of the bottle is inclined downward, and the cylinder is at an angle of 30° with the ground, or the end of the cylinder is raised by about 200-300mm.
3) Open the filling valve. When the system reaches a certain pressure (0.1～0.2 MPa for ammonia system; 0.2～0.3 MPa for freon system), stop the refrigerant charging, and then check the sealing conditions of the connections and welds of the system . If there is no leakage, you can continue to charge refrigerant.
4) Close the outlet valve on the accumulator and continue to charge refrigerant. When the pressure in the cylinder and the pressure in the reservoir reach equilibrium, the outlet valve on the reservoir should be opened.
5) Start the refrigerating machine, make the refrigerating device enter the running state, and continue to charge the refrigerant at the same time. When white frost appears on the lower part of the cylinder, it means that the liquid refrigerant in the cylinder is almost full. At this time, the cylinder valve and the feeding valve can be closed, and the bottle can be changed to continue feeding.
6) Unless the outside temperature is very low, there is generally no need to pour hot water into the cylinder to increase the pressure in the cylinder when charging the refrigerant, because it is unsafe to do so. If you need to speed up the filling speed, the hot water temperature should not exceed 50°C, and it is strictly forbidden to heat the cylinder in other ways.
7) When filling Freon, a filter drier must be installed on the special nozzle to reduce the possibility of water entering the system. When charging the high-pressure section, do not start the compressor, and pay attention to the exhaust valve not to leak air, otherwise liquid hammer will occur.
8) When the refrigerant is charged to 90% of the charged volume, the charging can be temporarily stopped, and the system can be tested to check whether the system consumption meets the operating requirements, so as to avoid unnecessary trouble caused by the excessive charging volume. For the old refrigeration system, when it is necessary to replenish the refrigerant, it should be charged from the low pressure side.
2, leak detection after filling
(1) The method of using test paper to detect leakage. Generally, phenolphthalein test paper is used to detect whether there is any leakage at the welds, flanges, and threaded connections of the system. Wet the test paper, and then approach the place to be inspected. If it turns red, it means that there is ammonia leakage (note that the test paper does not touch the soapy water on the tube to cause an illusion). You can also use litmus paper, which turns blue when exposed to ammonia.
(2) Halogen torch leak detection method Halogen torch is a commonly used leak detection tool in Freon refrigeration systems. The domestic halogen blowtorch is shown in the figure below, and the method of use is as follows:
1. Add alcohol: first unscrew the base 1 and add anhydrous alcohol with a purity of not less than 99.5% in the barrel, but the injection volume should not be too much. Fill 1/2 to 3/4 to fill the volume of the tube. Yes, then the base must be fastened.
2. Ignition: Turn the hand wheel 2 to the right, close the valve core, fill the glass, and then light it to heat the lamp tube and the upper part of the blowtorch. After a little heating, check whether the blowtorch is leaking.
3. Ignition: When the alcohol in the beaker is almost used up, turn the hand wheel 2 to the left to ignite the alcohol volatilized in the nozzle in the flame ring 4. At this time, the straw 6 of the halogen lamp makes the sound of inhaling gas, and you can start the inspection with the lamp. leak.
4. Use: When testing, move the suction nozzle of the suction hose 6 closer to the tested part and move slowly. If there is a leakage of Freon gas, it will decompose in an open flame. At this time, the orange-red flame will change to the color of green and flame. It changes with the amount of Freon leakage. The darker the color, the more serious Freon leakage.
