Pump for metering liquid additive for selective catalytic reduction device

The invention relates to a device (1) for the metered provision of a liquid, at least having at least one pump (2) for feeding the liquid, wherein the at least one pump (2) has a pump housing (3) with at least one inlet (4) and at least one outlet (5), wherein an eccentric (6) is arranged on the pump housing (3), and wherein a deformable diaphragm (7) is arranged between the pump housing (3) and the eccentric (6), wherein the deformable diaphragm (7) and the pump housing (3) bound at least one delivery path (8) from the at least one inlet (4) to the at least one outlet (5) and form at least one seal (9) of the delivery path (8), wherein the at least one seal (9) can be displaced, for the purposes of feeding, along the delivery path (8) with a delivery direction (27) from the at least one inlet (4) to the at least one outlet (5) by means of a movement of the eccentric (6), wherein a friction torque (13), which has to be overcome for the eccentric (6) to move, occurs within the at least one pump (2), and the friction torque (13) is greater than a maximum pressure torque (14) which can be generated by pressurised liquid in the delivery path (8), with the result that a movement of the eccentric (6) counter to the delivery direction (27) is prevented.