Abstract: A constant flow gas regulator apparatus adapted to be mounted inside of a vessel containing gas under high pressure which comprises an elongated regulator body having at least one flat surface, a conduit through said body with one end thereof terminating in an opening in the flat surface and an elongated, radiused, resilient spring reed having one end thereof operably secured to the flat surface with a portion of the reed extending over the opening in the flat surface in spaced relation thereto, whereby a substantially constant gas flow is maintained as the gas pressure in the vessel fluctuates or decreases. The regulator apparatus is particularly useful for metering oxygen from a portable container.