You balanced a pump impeller by placing a 5 gram weight at a radius of 100 mm. The original vibration amplitude was 10 mm/s, and after adding the balancing weight, the vibration is 1 mm/s. The speed of the pump is 1500 rpm and the weight of the impeller is 3 kg.
a) Calculate the residual unbalance, the eccentricity and the balancing quality grade according to ISO balancing standard.
b) The stiffness of the pump%u2019s shaft is 80 kN/m. Calculate the natural frequency for the pump impeller on the shaft (ignore the weight of the shaft).
c) What is going to happen if the pump speed is increased to 1560 rpm?