1; thermal expansion valve adjustment techniques and taboos    In order for the thermal expansion valve to perform the automatic adjustment function under one condition, it must be adjusted during the commissioning of the refrigeration system to ensure that the thermal expansion valve can perform the automatic adjustment correctly during system operation.   The adjustment of the thermal expansion valve is achieved by adjusting the rod. The rotation or unscrewing of the adjustment rod is essentially the compression or relaxation of the spring, that is, adjusting the static assembly superheat of the thermal expansion valve to meet the needs of the refrigeration condition. Generally, the spin is forward, and the reverse spin is retreat. When the evaporation pressure is to be adjusted, the cap can be removed, and the adjustment rod can be smoothly rotated with a wrench to increase the compression of the spring, forcing the diaphragm to move up and close the valve, and the evaporation pressure will gradually decrease. Similarly, the anti-rotation lever will open a large valve to increase the evaporation pressure.   When adjusting the thermal expansion valve, a low pressure gauge should be installed on the compressor suction shutoff valve to observe the change of evaporation pressure. The normal evaporation pressure is hoarfrost or condensation to the suction pipe (white frost in medium and low temperature equipment ; condensation on air conditioning equipment). If the hoar frost or condensation is connected to the suction shut-off valve, or even half of the compressor, the valve is too large, it should be adjusted smaller. If the hoarfrost or condensation only reaches the evaporator outlet or the outlet end, the valve is explained. Too small, should be adjusted up.    The commissioning of the thermal expansion valve can generally be carried out in two steps. The beginning is a coarse adjustment, that is, it can be rotated about one turn per adjustment. When the equipment is close to its operating conditions, fine-tuning is required, rotating 1/4~1/2 turns each time . After each adjustment, the system should be operated for a few minutes or ten minutes, and the change of the low pressure gauge should be observed to determine the next adjustment. When the expansion valve is commissioned, the cap should be screwed on and tightened with a wrench to prevent refrigerant leakage.    Adjusting the thermal expansion valve is a meticulous work, and it is urgent to adjust it during the adjustment process. The adjusted thermal expansion valve must not be adjusted for other reasons unless the chiller changes operating conditions. Generally, the unit that has been shipped from the whole machine, the thermal expansion valve has been adjusted before leaving the factory, and the unit should not be adjusted when it is commissioned on site.     2. Maintenance operation of thermal expansion valve     Common faults of the thermal expansion valve are blocked, and the working fluid leaked in the temperature sensing bag.   ( 1 ) The valve hole is blocked by the valve hole and there are two cases of ice blockage and oil blockage. If the refrigeration system contains water, it will dissolve in the refrigerant. The amount of dissolution is related to the temperature of the refrigerant. The high temperature is high, and the amount of dissolution is small. When the condensation temperature of the refrigerant liquid flows into the expansion is about 30t of the throttle valve opening, immediately cooled to a saturation temperature (evaporating temperature) evaporation pressure, a portion of the water to be separated, when attached to the valve hole portion evaporation temperature is below 0 ℃ It will form an ice layer, and when the ice layer increases, the valve hole will be blocked.     The refrigerating machine oil and the refrigerant also dissolve each other, and the amount of dissolution thereof is also related to temperature, the temperature is high, the amount of dissolution is large, and the temperature is low, and the amount of dissolution is small. When the temperature of the liquid expansion valve orifice is throttled and the temperature drops rapidly, part of the refrigeration oil is separated and sticks around the valve hole. When the evaporation temperature is lower than the freezing point of the refrigeration oil, the refrigeration oil will condense into a paste. As the oil gradually increases, the valve hole is blocked because the lower the evaporation temperature, the easier the water and oil are separated, so ice blockage and oil blockage can easily occur in low-temperature refrigeration equipment with lower evaporation temperatures.     1 ) Judging whether the valve hole is blocked by ice or blocked by oil. When the refrigeration unit starts running normally after a period of operation, the suction pressure drops rapidly to negative pressure (vacuum), the temperature of the reservoir (room) rises, the frost layer melts (first the frost layer of the suction tube melts), and the side ear does not hear. The sound of the flow to the expansion valve. At this time, it can be basically judged that the valve hole is blocked or the oil is blocked. To further confirm the valve hole is blocked, use an alcohol lamp heating expansion valve (without stopping), twelve minutes after heating, air sound heard when the sigh ......, but also hear the squeak then, the intake pressure recovery Then, the outlet of the expansion valve begins to whiten and the valve hole is indeed blocked by ice or oil.     2 ) The method of troubleshooting. Replace the desiccant in the dry filter. When the water content is large, the reagent grade anhydrous calcium chloride may be used first, and after the plasma is cooled for one or two days, the silica gel is replaced. If there is no drying filter in the system, you can temporarily attach a dry filter.   ( 2 ) The filter screen of the expansion valve inlet filter clogging expansion valve is the impurity dirt in the overcrowding, and the valve hole is not blocked. When there are more impurities in the filter, the mesh is not smooth or even completely unreasonable. The phenomenon is also that the inhalation vacuum is pulled, the temperature of the reservoir (chamber) does not drop, and the half or the entire expansion valve has a weak squeaking and intermittent sound, which means that the filter is not smooth and all are blocked. . When tapping the inlet connector of the valve with a wrench handle, if the sound is louder than the original sound, it is confirmed that most of the mesh of the filter is blocked and blocked. The situation is that the airflow of the refrigerant in the valve is not heard. Body also: Generally, it is ineffective to use a wrench handle to knock the mouth joint. However, the filter is completely blocked.      The obvious difference between the filter blockage and the valve hole blockage is that the valve hole is blocked during the normal operation time. If the unit starts to suck or pull the vacuum, the filter is blocked. The phenomenon that occurs when the refrigerant is insufficient and the phenomenon when the filter is clogged is very different when judging. When the refrigeration unit is running, if the expansion valve is heard, the sound is louder, the suction pressure is lower, the suction pressure gauge is fluctuating, the temperature of the reservoir (chamber) is not low enough, and some of the evaporation tubes are not covered with hoarfrost. If the refrigerant is insufficient, do not mistake the expansion valve. The method of removing the filter from the filter is to remove the filter and clean it with gasoline.    ( 3 ) Leakage of the working fluid in the induction mechanism When the tearing leaks in the sensing mechanism, the induced pressure of the temperature sensing bag disappears, causing the valve to close. When the tear refrigeration unit starts to operate, the vacuum is pulled, and the temperature in the chamber (the chamber) is not lowered at all, and the expansion valve has no airflow. Remove the expansion valve, remove the filter interface, and use the mouth to suction the outlet of the expansion valve, such as suction, and can be hung with the lips, indicating that the valve hole is not at all. It is true that the valve is not closed and the same type of expansion valve should be replaced . Drivers Leather Work Gloves,Premium Washable Leather Gloves,Unlined Men'S Leather Gloves,Straight Thumb Leather Gloves JINAN SHANDE SECURITY TECHNOLOGY CO., LTD , https://www.sdsxlb.com