A liquid handling device having an upstream liquid handling structure connected to a downstream liquid handling structure by a conduit. The upstream and downstream liquid handling structures are sealed or sealable such that the conduit provides the only fluidic communication paths between the upstream and downstream liquid handling structure. The device is arranged such that a driving force causes liquid in the upstream liquid handling structure to at least partially fill the conduit to separate gas in the upstream liquid handling structure from gas in the downstream liquid handling structure. With the device set up such that the two gas volumes are separated by a liquid volume, gas pressures and liquid flow in the device can be controlled by control of the driving force. The device may be arranged for rotation about an axis of rotation to provide the driving force.
