Resonance in the water circuit of a cooling tower

During the start-up tests of a cooling-tower circuit pressure resonance took place. With the aid of a mathematical model this resonance was investigated and the results were analyzed. The elastic behaviour of leaking non-return valves appeared to be responsible for the onset of the resonance. The preventive function of a by-pass around each valve, was analyzed. In the final startup test the leakage flow was eliminated and a by-pass had been installed for safety reasons. The measures taken proved to be satisfactory for all operating conditions. (orig.)