The inlet and outlet pipelines of the single screw have the same diameter; vibration and noise are significant at 100% speed
Thread Content
There are three single-screw pumps on site, equipped with variable-frequency motors; a stainless-steel elastic coupling is used to connect the pumps to the motors. Both the inlet and outlet pipelines have a diameter of DN200; the length of the inlet pipeline is approximately 80 meters. There are filters installed on the pipelines, and the medium transported is base oil with a viscosity of 1400 mm2/s. During operation on-site, when the speed of the variable-frequency motor was at 10%, 20%, and 50% respectively, the pump ran smoothly with no abnormalities in vibration or noise ； When the speed is increased to 100%, the pump produces obvious abnormal noises (to me, it sounds like the screws are directly grinding against each other), and there is significant vibration. What could be the cause of this?
During the testing process, all possible causes must be ruled out one by one. 1. Did this problem occur during pump testing? If so, it indicates that it has nothing to do with the process medium； 2. The problems will not be singular; for example, abnormal noises and vibrations will definitely cause temperature changes ； 3. If the motor runs smoothly throughout the testing process without any abnormalities, the possibility that the drive unit is the cause is essentially ruled out ； 4. The coupling alignment needs to be rechecked; if no issues are found upon rechecking, the possibility that alignment problems were the cause can be ruled out ； 5. If the problem manifests gradually, it is advisable to measure the vibration intensity of the pump casing at different rotational speeds; issues with the pump’s design itself, such as insufficient foundation strength or inadequate support rigidity, may be to blame ； I hope it can be inspiring.
When driving the unit on-site, the operator opens all the valves on the pump’s inlet and outlet pipelines to their full open position.