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An apparatus and method for generating a low concentration of gas within a carrier gas flow employing one or more miniature one-piece cylinders filled under pressure with a pure gas, or a concentrated gas balanced with an inert gas or gas mixture. Released from the cylinder through a pierced or othe

An apparatus and method for generating a low concentration of gas within a carrier gas flow employing one or more miniature one-piece cylinders filled under pressure with a pure gas, or a concentrated gas balanced with an inert gas or gas mixture. Released from the cylinder through a pierced or other controlled opening, the flow of the gas is regulated by a pressure regulator and a micro orifice to be blended into a steady stream of diluent gas, typically ambient air, to form a desired gas concentration. No gas is generated if the pressure of the gas in the cylinder, which is monitored constantly by a pressure transducer, is below a predetermined level. The apparatus can be built into a portable device, or an automated docking station (or calibration station) for testing and calibrating gas detection and monitoring instruments, or into a fixed gas detection system for performing such functions.

대표청구항 ▼

What is claimed is: 1. An apparatus for providing calibration gas to a gas monitoring instrument, comprising: a calibration gas source comprising a miniature gas cylinder containing a calibration gas, and including a pierceable seal or open/close valve; an outlet for providing test gas to the monit

What is claimed is: 1. An apparatus for providing calibration gas to a gas monitoring instrument, comprising: a calibration gas source comprising a miniature gas cylinder containing a calibration gas, and including a pierceable seal or open/close valve; an outlet for providing test gas to the monitoring instrument; and a gas conduit for providing diluted cylinder gas to the outlet, the gas conduit comprising: a receptacle means for receiving the miniature gas cylinder in gas-tight manner, and including means for rupturing the seal or opening the valve; a manifold; pressure transducer means for determining pressure of the gas in the conduit; a valve for releasing the gas into the gas conduit; a micro orifice for providing a controlled flow of calibration gas in the conduit; means for diluting gas in the conduit with air; and control means for releasing test gas to the conduit upon determination of sufficient pressure in the manifold. 2. The apparatus of claim 1, wherein the gas dilution means comprises a tee fitting with a leg of the tee fitting connected to a source of air. 3. The apparatus of claim 2, wherein the source of air is atmospheric air, and a filter is disposed between the atmospheric air and the tee fitting. 4. The apparatus of claim 3, additionally comprising a pump in combination with the tee fitting to provide a controlled flow of diluted calibration gas to the outlet. 5. The apparatus of claim 1, wherein the means for diluting comprises a source of compressed air connected by a valve to the conduit. 6. The apparatus of claim 1, wherein the gas source comprises a plurality of miniature gas cylinders, each cylinder being received in a said receptacle means. 7. The apparatus of claim 6, wherein each gas cylinder is connected to a common manifold, with a valve disposed between each receptacle means and the common manifold. 8. The apparatus of claim 7, wherein a single pressure transducer is connected between the valves and the common manifold. 9. The apparatus of claim 8, wherein the transducer controls a single pressure switch controlling flow of gas to the manifold. 10. The apparatus of claim 7, wherein a pressure transducer is connected between each valve and the common manifold. 11. The apparatus of claim 1, wherein the miniature gas cylinder has a volume of about 10-100 ml. 12. The apparatus of claim 1, wherein the receptacle includes a regulator. 13. The apparatus of claim 1, wherein the receptacle includes venting means for excess gas pressure. 14. The apparatus of claim 1, wherein the gas source is a single cylinder containing a plurality of gases. 15. The apparatus of claim 1, wherein the micro orifice has a diameter between 0.5 and 50 μm. 16. The apparatus of claim 1, wherein the calibration gas in the cylinder has a concentration of at least 0.1% by volume, and is diluted with a gas or gas mixture with which the calibration gas does not react. 17. The apparatus of claim 1, wherein the calibration gas in the cylinder has a concentration of 1-100% by volume. 18. The apparatus of claim 17, wherein the concentration is at least 98% by volume. 19. A method for providing a calibration gas to a gas detection instrument, comprising the steps of: disposing in a receptacle a miniature gas cylinder containing a calibration gas, and opening a seal in the cylinder to permit gas to flow into a gas conduit; determining pressure of the gas in the conduit, and verifying that said pressure is at least a predetermined level; passing the gas which is at least at said predetermined pressure through a micro orifice to control the flow of the gas to a predetermined rate; diluting the gas flowing at said predetermined rate with a diluting gas flowing at a known rate; and passing the diluted gas to an instrument to be calibrated. 20. The method of claim 19, wherein the calibration gas in the miniature cylinder has a concentration of at least 0.1% by volume, and is diluted with a gas or gas mixture with which the calibration gas does not react. 21. The method of claim 19, wherein the calibration gas in the cylinder has a concentration of 1-100% by volume. 22. The method of claim 21, wherein the concentration is at least 98% by volume. 23. The method of claim 19, wherein the orifice has a diameter between 0.5 and 50 μm. 24. The method of claim 19, wherein the diluting gas is filtered ambient air.