Abstract: A flow meter for measuring mass flow is disclosed having two vibrating U-shaped tubes, a means for vibrating the tubes, and sensors for detecting the coriolis force couple which results from the vibration and the flow of the material to be measured through the meter. The U-shaped tubes include spaced apart inlet and outlet sections connected to a fixed member at one end, and having the sensors at the other end thereof. The fixed ends are more closely spaced together than are the other ends having the sensors for increasing the moment arms acted on by the coriolis force couple for more easily detecting twist of said U-shaped tubes. The U-shaped tubes also are arranged to have the same natural of frequency for longitudinal oscillations and for torsional oscillations.

Abstract: Disclosed is an apparatus and its method of operation for an oil well valve having a self adjusting liquid spring responsive to changes in pressure in the well annulus. The valve has a liquid spring contained in a spring chamber divided by a piston means which moves responsive to annulus pressure changes to operate the valve. The piston means includes a metering means to meter liquid from one side of the piston to the other as the volume of the liquid changes due to pressure and temperature changes. The piston means moves responsive to pressure changes in the well annulus which pressure changes are applied to the well annulus at a rate faster than the metering means may relieve the changes. A mechanical spring means in conjunction with the metering means returns the piston means to its original position after a predetermined time.