Inspection method

A method for inspecting withstand pressure of a liquid feeding device, the liquid feeding device including

• a first cylinder,
• a first plunger that reciprocates in the first cylinder,
• a fluid tank that is connected to an upstream side of the first cylinder and stores a fluid to be fed,
• a first check valve that is connected to an upstream side of the first cylinder and prevents a backflow of the liquid to be fed from the first cylinder to the fluid tank,
• a second check valve that is connected to a downstream side of the first cylinder and prevents a backflow of the liquid to be fed from a flow path on a downstream side to the first cylinder, and
• a pressure sensor that is connected to a downstream side of the second check valve,
• the method comprising:
• a suction step of suctioning a fluid from the fluid tank into the first cylinder by driving the first plunger in a suction direction;
• a first step of driving the first plunger in a discharge direction after the suction step;
• a second step of stopping the first plunger for a predetermined first time;
• a third step of driving the first plunger in the discharge direction;
• and
• a fourth step of estimating a leakage amount in a flow path on an upstream side of the second check valve based on a detection value of a pressure detected by the pressure sensor from start of the second step to end of the third step.