The pulsator is used to test pipes and containers made from thermoplastic polymer for resistance to alternating pressure stress. The test specimen is fi lled with water and subjected to pressure cycles by the pulsator. The number of test cycles can be adjusted. The test pressure is applied in a pressure cylinder. Within the cylinder, the piston rod is moved up and down by a servo drive. The form and amplitude of the pressure curve is adjusted in accordance with the thermo drive activation. Depending on the version, 1 to 8 individually adjustable test stations have been installed. The test stations can be cascaded.