Reasons for screw compressor failure http://mehrespand.ir/ 1- Inappropriate oil temperature If the liquid injection system, which is used in some screw compressor models to cool the coil or compression chamber, is not temperature controlled and causes the temperature to drop below the design temperature, it can cause the refrigerant and oil to mix and form foam. http://mehrespand.ir/?p=1478 The result of this is a product that is not capable of lubrication and, instead of lubricating and absorbing the heat of the parts, causes more friction. The oil problem cannot be summarized only in low temperature. High oil temperature also causes the parts to not absorb the temperature and the overall temperature of the compressor increases. We will also have another double problem, which is decomposition or #oil decomposition. Every oil decomposes at a certain temperature and creates an acidic structure, which is explained in the compressor oil video. 2- Crankcase heater problem: In cases where the crankcase heater or oil separator heater does not work properly and is not in the circuit when the compressor is off, the gas will condense in the crankcase or oil separator due to the compressor cooling and the increase in compressor pressure during shutdown. Due to the heaviness of the freon gas compared to the oil, it will go below the oil surface and boil when the compressor starts and the pressure decreases, and it will mix with the oil and occupy a very large volume, causing hydraulic shocks and damage to the bearings and increasing the amperage consumed. 3- Slide valve not working properly Slide valve problems can be divided into several categories. In some cases, it is observed that the compressor capacity control logic has not been properly programmed by the chiller manufacturer, causing the compressor to operate at low loads. Note that capacities such as 25% or 33% should only be used for starting and shutting down the compressor, and avoid operating the compressor at low loads. Also, in the event of #overheating or excessive heating of the compressor, the edges of the slider location become sharp and the possibility of the slider locking increases, which must be taken into account during repairs. If the slide does not work properly, we should expect an increase in the amperage consumed and the failure of the bearings, a decrease in the compressor capacity, and the compressor overheating. 4- Incorrect installation or incorrect selection of bearings When repairing screw compressors, the compressor bearing must be replaced with great care. Avoid removing the bearing cones from the screws with a hammer and a pen. As you can see in the picture, the experts of the Mehraspand Engineering Group use special tools to remove the cones. If the bearings are installed in the wrong direction, the lifespan of the bearings is greatly reduced, which is explained in the screw compressor bearings video. Hammers and heat should not be used to install bearings. The company's experts cool the screws to minus 210 degrees Celsius with liquid nitrogen and heat the bearings to the permitted temperature with a heater based on the bearing manufacturer's specifications, thus creating a clearance of up to 0.5 mm, which makes it easy to install the bearing housing. The use of a press machine and special tools is also permitted.