Abstract: A method of determining the predicted usage of gas from a gas cylinder and valve assembly. The method comprises determining, using a sensor assembly and at a time t, the mass of gas in the gas cylinder, the average flow rate of gas from the gas cylinder; and the time remaining until the quantity of gas in the gas cylinder reaches a predetermined level, the time remaining being determined, at time t, from the mass of gas in the gas cylinder, the average flow rate of gas from the gas cylinder, and a predetermined scaling factor selected in dependence upon the proportion of gas remaining in the gas cylinder. The average flow rate is determined based on previous measurements, and the amount of gas remaining in the gas cylinder.

Abstract: A method of determining the predicted usage of gas from a gas cylinder and valve assembly. The method comprises determining, using a sensor assembly and at a time t, the mass of gas in the gas cylinder, the average flow rate of gas from the gas cylinder; and the time remaining until the quantity of gas in the gas cylinder reaches a predetermined level, the time remaining being determined, at time t, from the mass of gas in the gas cylinder, the average flow rate of gas from the gas cylinder, and a predetermined scaling factor selected in dependence upon the proportion of gas remaining in the gas cylinder. The average flow rate is determined based on previous measurements, and the amount of gas remaining in the gas cylinder.

Abstract: There is provided a method of, and apparatus for, measuring the mass of a gas under pressure using a piezoelectric oscillator. The gas is contained within a pressure vessel (100) having a fixed internal volume (V) and the piezoelectric oscillator (202) is immersed in the gas within the pressure vessel (100). The method comprises: a) utilizing said piezoelectric oscillator (202) to measure the density of the gas within the high-pressure vessel (100); b) determining, from the density measurement and from the internal volume (V) of said pressure vessel, the mass of the gas within the pressure vessel (100). By providing such a method, the true contents (i.e. mass) of fluid in a pressure vessel such as a cylinder can be measured directly without the need to compensate for factors such as temperature or compressibility. This allows a determination of mass through direct derivation from the density of the gas in the cylinder, reducing the need for additional sensors or complex calculations to be performed.

Abstract: There is provided a pressure gauge for measuring the pressure of a gas. The pressure gauge comprises a housing connectable to the gas source and comprising an interior which is, in use, in communication with said gas. The pressure gauge further comprising a sensor assembly located within said housing and including a piezoelectric oscillator which, in use, is located in contact with said gas, said sensor assembly being arranged to measure the oscillation frequency of said piezoelectric oscillator in said gas and configured to determine, from the frequency measurement and the known temperature and known molecular weight of the gas, the pressure of the gas. By providing such an arrangement, an overpressure proof yet accurate pressure gauge can be provided. This is in contrast to conventional gauges which are damaged permanently by overpressure situations.

Abstract: There is provided a pressure gauge for measuring the pressure of a gas. The pressure gauge comprises a housing connectable to the gas source and comprising an interior which is, in use, in communication with said gas. The pressure gauge further comprising a sensor assembly located within said housing and including a piezoelectric oscillator which, in use, is located in contact with said gas, said sensor assembly being arranged to measure the oscillation frequency of said piezoelectric oscillator in said gas and configured to determine, from the frequency measurement and the known temperature and known molecular weight of the gas, the pressure of the gas. By providing such an arrangement, an overpressure proof yet accurate pressure gauge can be provided. This is in contrast to conventional gauges which are damaged permanently by overpressure situations.

Abstract: There is provided a method of and apparatus for, measuring the mass of a gas under pressure using a piezoelectric oscillator. The gas is contained within a pressure vessel (100) having a fixed internal volume (V) and the piezoelectric oscillator (202) is immersed in the gas within the pressure vessel (100). The method comprises: a) utilising said piezoelectric oscillator (202) to measure the density of the gas within the high-pressure vessel (100); b) determining, from the density measurement and from the internal volume (V) of said pressure vessel, the mass of the gas within the pressure vessel (100). By providing such a method, the true contents (i.e. mass) of fluid in a pressure vessel such as a cylinder can be measured directly without the need to compensate for factors such as temperature or compressibility. This allows a determination of mass through direct derivation from the density of the gas in the cylinder, reducing the need for additional sensors or complex calculations to be performed.