Flow passage adapter

A flow passage adapter configured to be attached to an inflow port of a flow rate measuring unit to introduce a measurement target fluid into the flow rate measuring unit, the flow passage adapter comprising:

• a flow passage which is disposed in a body of the flow passage adapter and through which the measurement target fluid is to flow;
• and
• a plurality of ribs disposed in the flow passage such that the measurement target fluid introduced into the flow passage collides with the plurality of ribs,
• the flow passage adapter being configured to be attached to the flow rate measuring unit such that the flow passage adapter covers the inflow port of the flow rate measuring unit,
• the inflow port of the flow rate measuring unit being a first inflow port,
• the flow passage includes an introduction flow passage for the measurement target fluid,
• the introduction flow passage having a second inflow port extending in a direction opposite to a flowing direction to the flow rate measuring unit,
• the introduction flow passage having a first opening at the second inflow port into which the measurement target fluid is to flow,
• the first opening opening toward a first direction,
• the introduction flow passage further having a second opening which opens toward a second direction different from the first direction, and
• in a state in which the flow passage adapter is attached to the flow rate measuring unit, the second opening of the introduction flow passage is closed with an outer wall forming a measurement flow passage of the flow rate measuring unit so as to form the introduction flow passage.