Pressure oscillation and the damper function Pressure [Bar] Oscillation of the pump discharge pressure Time At certain low discharge pressure of the pump, there is no oscillation. With increase of the pressure, the oscillation starts. The frequency of the oscillation is about 3 Hz. The amplitude (p2p) is about 1 bar. Temperature of the damper [˚C] Pressure [Bar] Effect of the damper Damper on (with heating) Damper off (without heating) Oscillation is due to not enough heat load in the dummy load. JT valve of the chiller is active. Damper has no obvious effect on the damping of the oscillation. Test station connected with the large scale system From the large scale system To the large scale system P2 P1 Pressure measurement in the test station Time [s] In the test station, the pressure P1 before the JT expansion valve still oscillates with the same frequency as the discharge pressure of the pump. Much less amplitude (25mbar) After JT expansion, the pressure P2 has no oscillation. It is possibly dampened by the JT expansion valve and the capillary connected with the pressure sensors P1 and P2. PT1106 Suction side pressure before the chiller Time [s] The suction side pressure PT1106 before the chiller of the large scale system has no oscillation too. It seems the oscillation has no effect on the pressure drop measurement along the test section.