Abstract: An inner diameter plug for sealing a pipe near an open end of the pipe. The plug is capable of being reused within a range of pipe inner diameter tolerances and of providing effective fluid-tight sealing over a range of internal pressures. The plug can be hand tightened and provides self-gripping and self-sealing features.

Abstract: A flowmeter for liquids is provided having a through passageway for the flow to be measured with a fluid interaction chamber and feedback means to provide an oscillation of the flow. The frequency of this oscillation is linearly and proportionally related to volume rate of flow and is independent of all fluid properties in the turbulent range, i.e., the frequency for a given volume flow rate will be the same for any liquid as long as the flow is turbulent. Provisions are made for detecting this oscillation and a sensor is provided which is responsive to changes in the heat transfer rates to the surrounding media. Vent means is provided communicating with the feedback means for venting gaseous material from the feedback passageways so that the flowmeter can be mounted and operate properly in a vertical pipe section.