Abstract: There is provided a gas mixer arrangement comprising a first gas source for supplying a first gas; a second gas source for supplying a second gas different from said first gas; first and second flow regulation devices for regulating the respective flow of the first gas and second gases from the first and second gas sources; a mixer; and an outlet. The mixer is located downstream of the first and second flow regulation devices and arranged, in use, to mix the first and second gases to provide a mixed gas to the outlet.

Abstract: There is provided a method of automatically controlling the mass flow rate of a gas through an orifice through which, in use, choked flow is arranged to occur. The method uses an electronic valve located downstream of a gas source, a piezoelectric oscillator in contact with the gas upstream of the orifice and downstream of the electronic valve and a temperature sensor. The method comprises: a) driving the piezoelectric crystal oscillator at a resonant frequency b) measuring the resonant frequency of the piezoelectric oscillator c) measuring the temperature of the gas; and d) controlling the electronic valve in response to the resonant frequency of the piezoelectric oscillator and the temperature of the gas in order to regulate the mass flow rate of gas through said orifice.

Abstract: There is provided a gas mixer arrangement comprising a first gas source for supplying a first gas; a second gas source for supplying a second gas different from said first gas; a first valve for regulating the flow of the first gas; a second valve for regulating the flow of the second gas; a mixer located downstream of the first and second valves and arranged, in use, to mix the first and second gases to provide a mixed gas; a meter arranged to measure the average molecular weight of the mixed gas, comprising a high-frequency planar piezoelectric crystal oscillator in contact with the mixed gas and a sensor operable to determine atmospheric pressure; and a controller operable, in response to the measured average molecular weight of said mixed gas, to control at least one of said first and second valves in order to control the relative proportion of the first and second gases in said mixed gas.

Abstract: There is provided a sensor assembly (200) for measuring physical properties of a gas under pressure within a pressure vessel (100). The sensor assembly (200) comprises a housing and a piezoelectric oscillator (202) for immersion in the gas within the pressure vessel (100). The sensor assembly (200) is arranged, when immersed in said gas, to measure the density of the gas within the pressure vessel (100). The housing comprises a first chamber and a second chamber. The first chamber is in fluid communication with the second chamber and substantially encloses said piezoelectric oscillator. The second chamber is in fluid communication with the interior of the pressure vessel. By providing such an arrangement, the true contents (i.e. mass) of fluid in a pressure vessel such as a cylinder can be measured directly and accurately.

Abstract: There is provided a meter for measuring the molecular weight of a gas, the meter comprising a housing having an inlet and an interior for receiving said gas to be measured, a sensor assembly comprising a high-frequency planar piezoelectric crystal oscillator located within said housing so that, in use, the piezoelectric crystal oscillator is in contact with said gas, said sensor assembly being arranged: to drive the piezoelectric crystal oscillator such that the piezoelectric crystal oscillator resonates at a single resonant frequency; to measure said single resonant frequency of said piezoelectric crystal oscillator to determine the density of gas; and to determine from the density, determined or pre-determined pressure of the gas and determined or pre-determined temperature of the gas, the molecular weight of the gas.

Abstract: There is provided a meter for measuring the mass flow rate of a gas, the meter comprising a conduit through which the gas flows in use, the conduit having a flow restriction orifice through which choked flow occurs in use, the flow restriction orifice dividing the conduit into an upstream portion upstream of said orifice and a downstream portion downstream of said orifice, the meter further comprising a sensor assembly including a first piezoelectric crystal oscillator in said upstream portion such that said first piezoelectric oscillator is in contact with said gas when the meter in use, a second piezoelectric crystal oscillator in said downstream portion such that said second piezoelectric oscillator is in contact with said gas when the meter in use, said sensor assembly being arranged: to drive the first and second piezoelectric crystal oscillators such that each of the first and second piezoelectric crystal oscillators resonate at respective resonant frequencies; to measure the resonant frequency of the f

Abstract: There is provided a meter (200; 350) for measuring the mass flow rate of a gas. The meter comprises a conduit (206) through which the gas flows in use. The conduit has a flow restriction orifice (212) through which choked flow occurs in use. The flow restriction orifice divides the conduit into an upstream portion (214) upstream of said orifice and a downstream portion (216) downstream of said orifice. The meter further comprises a sensor assembly (204), the sensor assembly including a piezoelectric crystal oscillator (218) in said upstream portion such that said piezoelectric oscillator is in contact with said gas when the meter in use. The sensor assembly is arranged: to drive the piezoelectric crystal oscillator such that the piezoelectric crystal oscillator resonates at a resonant frequency; to measure said resonant frequency of said piezoelectric crystal oscillator; and to determine, from the resonant frequency, the mass flow rate through the orifice.

Abstract: There is provided a method of measuring the physical properties of a two-phase fluid using at least one piezoelectric oscillator immersed in the two-phase fluid, the two-phase fluid comprising a gas fraction and a liquid fraction, the method comprising: a) measuring the resonant frequency of the or each piezoelectric oscillator as a function of time; and b) determining, from the or each resonant frequency, at least one physical property of the two-phase fluid to characterize the two-phase fluid.

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 method of automatically controlling the mass flow rate of a gas through an orifice through which, in use, choked flow is arranged to occur. The method uses an electronic valve located downstream of a gas source, a piezoelectric oscillator in contact with the gas upstream of the orifice and downstream of the electronic valve and a temperature sensor. The method comprises: a) driving the piezoelectric crystal oscillator at a resonant frequency b) measuring the resonant frequency of the piezoelectric oscillator c) measuring the temperature of the gas; and d) controlling the electronic valve in response to the resonant frequency of the piezoelectric oscillator and the temperature of the gas in order to regulate the mass flow rate of gas through said orifice.

Abstract: There is provided a meter for measuring the flow rate of a gas along a conduit, the meter comprising a sensor assembly including a piezoelectric crystal oscillator comprising two planar tines in contact with, and extending into, said gas flow when the meter is in use, said sensor assembly being arranged: to measure the voltage generated by movement of the planar tines of said piezoelectric oscillator in the gas flow along the conduit; and to determine, from the generated voltage, the flow rate of gas along said conduit.

Abstract: There is provided a gas mixer arrangement comprising a first gas source for supplying a first gas; a second gas source for supplying a second gas different from said first gas; first and second flow regulation devices for regulating the respective flow of the first gas and second gases from the first and second gas sources; a mixer, and an outlet. The mixer is located downstream of the first and second flow regulation devices and arranged, in use, to mix the first and second gases to provide a mixed gas to the outlet.

Abstract: There is provided a sensor assembly (200) for measuring physical properties of a gas under pressure within a pressure vessel (100). The sensor assembly (200) comprises a housing and a piezoelectric oscillator (202) for immersion in the gas within the pressure vessel (100). The sensor assembly (200) is arranged, when immersed in said gas, to measure the density of the gas within the pressure vessel (100). The housing comprises a first chamber and a second chamber. The first chamber is in fluid communication with the second chamber and substantially encloses said piezoelectric oscillator. The second chamber is in fluid communication with the interior of the pressure vessel. By providing such an arrangement, the true contents (i.e. mass) of fluid in a pressure vessel such as a cylinder can be measured directly and accurately.

Abstract: There is provided a gas mixer arrangement comprising a first gas source for supplying a first gas; a second gas source for supplying a second gas different from said first gas; a first valve for regulating the flow of the first gas; a second valve for regulating the flow of the second gas; a mixer located downstream of the first and second valves and arranged, in use, to mix the first and second gases to provide a mixed gas; a meter arranged to measure the average molecular weight of the mixed gas, comprising a high-frequency planar piezoelectric crystal oscillator in contact with the mixed gas and a sensor operable to determine atmospheric pressure; and a controller operable, in response to the measured average molecular weight of said mixed gas, to control at least one of said first and second valves in order to control the relative proportion of the first and second gases in said mixed gas.

Abstract: There is provided a meter for measuring the mass flow rate of a gas, the meter comprising a conduit through which the gas flows in use, the conduit having a flow restriction orifice through which choked flow occurs in use, the flow restriction orifice dividing the conduit into an upstream portion upstream of said orifice and a downstream portion downstream of said orifice, the meter further comprising a sensor assembly including a first piezoelectric crystal oscillator in said upstream portion such that said first piezoelectric oscillator is in contact with said gas when the meter in use, a second piezoelectric crystal oscillator in said downstream portion such that said second piezoelectric oscillator is in contact with said gas when the meter in use, said sensor assembly being arranged: to drive the first and second piezoelectric crystal oscillators such that each of the first and second piezoelectric crystal oscillators resonate at respective resonant frequencies; to measure the resonant frequency of the f

Abstract: There is provided a method of measuring the physical properties of a two-phase fluid using at least one piezoelectric oscillator immersed in the two-phase fluid, the two-phase fluid comprising a gas fraction and a liquid fraction, the method comprising: a) measuring the resonant frequency of the or each piezoelectric oscillator as a function of time; and b) determining, from the or each resonant frequency, at least one physical property of the two-phase fluid to characterise the two-phase fluid.

Abstract: A gas storage container may be filled with gas under pressure by feeding cryogenic fluid comprising liquefied gas into the container through a first conduit arrangement in a nozzle inserted into a passageway through a fluid flow control unit mounted in an opening in said container; closing the container to the passage of gas into or out of said container; and allowing said cryogenic fluid to become gaseous within the closed container. The invention involves venting displaced air and/or gaseous cryogenic fluid from said container during the feeding step through a second conduit arrangement in the nozzle. In embodiments in which displaced air and/or gaseous cryogenic fluid flows through the second conduit arrangement around a length of the first conduit arrangement, heat transfer from the fluid flow control unit to said cryogenic fluid is suppressed thereby reducing the level of evaporation of the cryogenic fluid in the nozzle during fill.

Abstract: A system for providing a high purity acetylene comprising 100 ppm or less solvent to a point of use comprising a storage vessel that houses an acetylene feed steam comprising acetylene and solvent; a cooling system that maintains the storage vessel and provides the acetylene feed stream at a temperature ranging from 20° C. to ?50° C.; and a purifier in fluid communication with the storage vessel wherein the acetylene feed stream is introduced into the purifier at a temperature ranging from ?50° C. to 30° C. to remove at least a portion of the solvent contained therein and provide the high purity acetylene.

Abstract: At least one inner vessel is provided within a container for storing and/or dispensing gas under pressure to assist in filling the container with gas. The container comprises an outer vessel defining an interior space and a fluid flow control unit for controlling fluid flow into and out of the container. The inner vessel(s) defines a part of the interior space of container and is intended to hold cryogenic fluid in spaced relationship with respect to the outer vessel. Since the inner vessel is in fluid flow communication with the remaining part of the interior space, when the cryogenic fluid becomes gaseous, the container fills with gas. The inner vessel(s) has a mouth for receiving cryogenic fluid from the fluid flow control unit which is free of the fluid flow control unit.