A pump arrangement (5) for use with a breast pump device comprises a pump element (51), an expression kit air conduit (55) designed to allow for air connection of an expression kit (2) of the device to the pump arrangement (5), a volume element (54) configured to store vacuum in the pump arrangement (5), and a storage switching mechanism (58) arranged between the expression kit air conduit (55) and the volume element (54), configured to switch between a position of direct connection of the expression kit air conduit (55) to the volume element (54) at a bypass position with respect to the pump element (51) and a position of disconnection of the expression kit air conduit (55) from the volume element (54). Through a direct exchange of vacuum between an expression kit (2) and the volume element (54), support of the functioning of the pump element (51) is realized.
