A central tire inflation system for maintaining tire inflation on a vehicle, the central tire inflation system comprising: a conduit forming a fluid flow path to place a vehicle air source in fluid communication with at least one vehicle tire; and a flow sensor in fluid communication with the conduit and the at least one vehicle tire; characterized in that: the flow sensor comprises at least two pressure sensors coupled to different ends of a narrowed orifice; the central tire inflation system further comprising: a temperature sensor; a mass flow sensor unit operably connected to the flow sensor and the temperature sensor, the mass flow sensor unit comprising: a calculator, the calculator to receive at least one flow signal generated from the at least two pressure sensors of the flow sensor and at least one temperature signal from the temperature sensor, wherein the calculator calculates a mass flow rate based on the at least one flow signal and the at least one temperature signal, and the calculator outputs a mass flow rate signal; a comparator, the comparator to receive the calculated mass flow rate form the calculator and compare the mass flow rate to a first flow rate threshold, wherein the comparator outputs an alarm signal when the mass flow rate violates the first flow rate threshold; a transmitter, the transmitter to emit the mass flow rate signal and the alarm signal; and a display, the display viewable by an operator and operably connected to the mass flow sensor unit, wherein the display receives the emitted mass flow rate signal and alarm signal and is configured to display the mass flow rate and to alarm when the alarm signal is received. a conduit forming a fluid flow path to place a vehicle air source in fluid communication with at least one vehicle tire; and a flow sensor in fluid communication with the conduit and the at least one vehicle tire; the flow sensor comprises at least two pressure sensors coupled to different ends of a narrowed orifice; the central tire inflation system further comprising: a temperature sensor; a mass flow sensor unit operably connected to the flow sensor and the temperature sensor, the mass flow sensor unit comprising: a calculator, the calculator to receive at least one flow signal generated from the at least two pressure sensors of the flow sensor and at least one temperature signal from the temperature sensor, wherein the calculator calculates a mass flow rate based on the at least one flow signal and the at least one temperature signal, and the calculator outputs a mass flow rate signal; a comparator, the comparator to receive the calculated mass flow rate form the calculator and compare the mass flow rate to a first flow rate threshold, wherein the comparator outputs an alarm signal when the mass flow rate violates the first flow rate threshold; a transmitter, the transmitter to emit the mass flow rate signal and the alarm signal; and a display, the display viewable by an operator and operably connected to the mass flow sensor unit, wherein the display receives the emitted mass flow rate signal and alarm signal and is configured to display the mass flow rate and to alarm when the alarm signal is received. a temperature sensor; a mass flow sensor unit operably connected to the flow sensor and the temperature sensor, the mass flow sensor unit comprising: a calculator, the calculator to receive at least one flow signal generated from the at least two pressure sensors of the flow sensor and at least one temperature signal from the temperature sensor, wherein the calculator calculates a mass flow rate based on the at least one flow signal and the at least one temperature signal, and the calculator outputs a mass flow rate signal; a comparator, the comparator to receive the calculated mass flow rate form the calculator and compare the mass flow rate to a first flow rate threshold, wherein the comparator outputs an alarm signal when the mass flow rate violates the first flow rate threshold; a transmitter, the transmitter to emit the mass flow rate signal and the alarm signal; and a calculator, the calculator to receive at least one flow signal generated from the at least two pressure sensors of the flow sensor and at least one temperature signal from the temperature sensor, wherein the calculator calculates a mass flow rate based on the at least one flow signal and the at least one temperature signal, and the calculator outputs a mass flow rate signal; a comparator, the comparator to receive the calculated mass flow rate form the calculator and compare the mass flow rate to a first flow rate threshold, wherein the comparator outputs an alarm signal when the mass flow rate violates the first flow rate threshold; a transmitter, the transmitter to emit the mass flow rate signal and the alarm signal; and a display, the display viewable by an operator and operably connected to the mass flow sensor unit, wherein the display receives the emitted mass flow rate signal and alarm signal and is configured to display the mass flow rate and to alarm when the alarm signal is received.