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This post was last edited by Beautiful mountains and clear waters_KJNI on 2019-3-29 at 13:58. I. Working Principle: A Roots blower is a type of positive-displacement blower. It consists of an approximately oval-shaped casing together with two partition plates that form a cylinder (the casing has an inlet and an outlet). There is a pair of impellers that mesh with each other (although there is a gap between them, they do not actually come into contact); these impellers rotate in opposite directions at equal speeds thanks to synchronous gear transmission. The meshing between the two impellers serves to separate the inlet from the outlet； During rotation, the gas inside the cylinder volume is pushed from the intake port to the exhaust port. II. Assembly clearance: There is relative motion between the impellers of a rotary vane blower, as well as between the impellers and the casing; since they are in a non-contact state, an appropriate working clearance is necessary to ensure both sealing and proper operation of the blower. The assembly clearance is the theoretical static clearance value at 20°C. It ensures that the working clearance required under dynamic conditions is met at rated operating conditions. To this end, the assembly clearance is an important factor in ensuring the performance and safe operation of the fan. Each Roots blower is adjusted for its assembly clearance at the time of leaving the factory, and users must not make any changes to it. The specific clearance values are shown in the table below: Table of assembly clearances for Roots blowers. Unit: mm. Under conditions that ensure the proper performance and normal operation of the Roots blower, the above clearance values may be adjusted appropriately. III. Clearance adjustment 1. Adjustment of clearance 1: Loosen the fastening bolts between the gear ring and the gear hub, remove the positioning taper pin, and adjust the installation angle between the gear ring and the gear hub. This achieves the purpose of adjusting the gap δ1. After adjusting the clearance, it is necessary to correct the positioning pin hole (or reposition it) before using a tapered pin for positioning. And tighten the fastening bolts. Adjusting the clearance should be done during a 360° rotation of the impeller. 2. Adjustment of clearance 2: Loosen the fastening bolts between the casing and the wall panel, and remove the positioning dowel. Depending on the specific situation and the relative position of the high-speed casing and the wall panel, adjust the radial clearance between the rotor and the casing. Once adjusted, it is necessary to correct the positioning pin holes (or install new ones), and then use the dowel for positioning. Then, the housing and wall panel are fastened together using bolts. 3. For adjusting gaps 3 and 4, there are fixing screws and adjustment screws on the bearing housing of the end wall panel; to reduce 3 and increase 4, the fixing screws should be loosened first. Tighten the adjustment screw again; this will cause the impeller to move toward the positioning end wall plate. Conversely, if 3 is increased while 4 is decreased, first loosen the adjustment screw and then tighten the fixing screw – this will cause the impeller to move toward the non-positioning end wall plate. As shown in Figure 3, to ensure coaxiality, it is necessary to add or remove shims between the bearing housing flange and the wall plate so that the gap between them remains roughly consistent, thereby preventing changes in that gap. If 3 meets the requirements but 4 does not, paper shims can be added or removed between the casing and the non-positioning end wall plate. V. Requirements after gap adjustment: An no-load test run must be carried out after the gap has been adjusted. VI. Maintenance and Repair of Roots Blowers The safe operation and service life of Roots blowers depend on proper and regular maintenance, as well as attention to any signs of potential problems. In addition to following the general maintenance procedures, special attention should be paid to the following points: 1) Check the tightness of all components and ensure that the positioning pins are not loose. 2) Check whether there is any water or oil leakage inside the blower casing. 3) There should be no scaling, rusting, or peeling inside the blower casing. 4) Pay attention to whether lubrication and cooling are functioning properly, as well as the quality of the lubrication. Regularly check for any abnormal noises during the operation of the blower. Check whether the unit is operating under conditions that do not meet the specifications. 5) The overload of the blower may not be apparent immediately; therefore, it is necessary to pay attention to the trends in inlet and outlet pressures, bearing temperature, and motor current in order to determine whether the machine is operating properly. 6) Before disassembling the machine, it is necessary to measure all the fitting dimensions of the machine, keep records of them, and mark the components accordingly, so as to ensure that the original fitting requirements are maintained after reassembly. 7) The bearings and gears of the blower are lubricated by splash lubrication; N68-N150 extreme pressure industrial gear oil is recommended. Users may also choose an appropriate lubricant of their own, provided that it has properties comparable to those of the aforementioned oils to ensure proper operation of the gears and bearings. When the machine is shut down, the oil level in the tank should be kept 3–5 mm above the midpoint of the oil gauge. The lubricating oil should be replaced regularly (the first time is after 200 hours of operation, for the initial oil change), and thereafter every six months. Before filling with new oil, the fuel tank and gears should be cleaned thoroughly with neutral kerosene. 8) Maintenance and repairs should involve the establishment of a reasonable maintenance schedule based on actual usage, with these tasks being carried out on a regular basis and proper records kept. It is recommended to conduct a thorough overhaul once a year, along with the replacement of bearings and other vulnerable components.