Flow rate measuring method and flowmeter, flow rate measuring section package used for them and flow rate measuring unit using them, and piping leakage inspection device using flowmeter

A piping leakage inspection apparatus which inspects a leakage of a liquid from a piping to be measured, comprising:

• an internal piping system comprising a connection end for communication with the piping to be measured, and a liquid discharge end;
• a tank for temporarily storing a pressurized liquid, which is connected to the internal piping system;
• and a pump and a flowmeter disposed in order in a path extending to the connection end from the tank for temporarily storing the pressurized liquid in the internal piping system, wherein the internal piping system is capable of forming a first path which transfers the liquid into the tank for temporarily storing the pressurized liquid from the piping to be measured through the connection end by the pump without passing the liquid through the flowmeter, a second path for pressure-feeding the liquid into the piping to be measured from the tank for temporarily storing the pressurized liquid through the flowmeter and the connection end by the pump, and a third path for transferring the liquid into the liquid discharge end from the tank for temporarily storing the pressurized liquid by the pump, and
• the leakage of the liquid from the piping to be measured is inspected based on a liquid flow rate detected by the flowmeter at a time when a liquid pressure of a part of the second path extending to the connection end from the pump is raised by the liquid pressure-feeding by the pump in a state in which the connection end is connected to the piping to be measured.