| HOUSING AND PROPELLER Virtually all renowned manufacturers use PBT with 15-30% fibreglass. Significant differences in stability (rigidity) are caused by different processing temperatures, the percentage of fibreglass and tools of not optimum design. SEPA® fans have virtually perfect plastic parts of PBT with 30% fibreglass. Problems: Poor dimensional accuracy, in particular the position of the rotor to the frame can cause the fan to become deformed when it is installed in the device. Test: Check the torsional rigidity of the fan frame by hand. Visually check the plastic parts. Conspicuous formation of burrs is a sign of processing problems. ROTOR CONSTRUCTION The fans are often subject to high dust pollution. A construction that makes it difficult for dust to penetrate is of major importance for the reliable operation of the fan. SEPA® fans are designed so that it is virtually impossible for particles of dust and water to reach the motor and penetrate the bearing system as the rotor shakes them off by centrifugal force. Problem: Rotors that are inadequately protected against dust with 3 through bores that point more or less accurately to the industrial bearing facilitate the penetration of dust and water with the risk of early failures or at least limited reliability. BALANCING Virtually no manufacturer balances the rotor of small fans as this is an expensive procedure. If it is balanced at all, this is done by applying weights or boring out. SEPA® fan rotors are balanced, if necessary, by boring out and additionally precisely balanced by using UV glue that can be dispensed precisely. Problems: Unbalance means bearing load (service life) and vibration (noise). visually checking the balancing characteristics on the inside of the rotor. |