The AR Valve of our SSV series 18, 19 and 20 is a reliable device that automatically protects centrifugal pumps against wear, total loss and damage that can result from running dry, from cavitation or from operating under low-load conditions, generally suitable for pressures up to 140 bar (SSV18) or up to 180 bar (SSV19). As soon as the main flow falls below the required minimum flow, the valve opens its bypass to the extent that the required pump minimum flow is discharged even if the main flow is zero. The pressure in the bypass is reduced via an inte­grated throttle line with a bypass non-return valve. The SSV series 10, 11 and 12 work with pressure reduction in the bypass by throttles only.