A device providing gas-powered logic responsive to a sensor such as a gas discharging type level probe and actuating valving controlling flow of liquid to be dispensed; and adapted to valving either for a volatile, especially cryogenic liquid utilizing the liquid's vapor pressure from a free gas space in a storage vessel top region as a power source both for control function and for the liquid transfer through a valve to a receiver, or with use of a separate gas supply for powering the probe, logic and amplifier, valving which applies liquid transferring pressure to a free gas space of a source vessel or vents the same for liquid transfer cut off, for volatile or non-volatile liquid.