Flow rate adjusting device

A flow rate adjusting device comprising:

• an ultrasonic flow metering portion configured to measure a propagation time difference between ultrasonic waves transmitted by a pair of oscillators disposed at an upstream side and a downstream side of a straight tube-shaped measurement flow channel to obtain a flow rate of a fluid, the fluid flowing from an inflow port and being circulated through the measurement flow channel;
• a flow rate adjusting portion configured to adjust the flow rate of the fluid flowing out to an outflow port from the downstream side of the measurement flow channel;
• a control portion configured to control the flow rate adjusting portion in such a manner that the flow rate of the fluid measured by the ultrasonic flow metering portion matches a set value preliminarily set;
• a pressure measuring portion configured to measure a pressure of the fluid flowing into the upstream side of the measurement flow channel from the inflow port;
• and
• a storage portion configured to store information that associates the flow rate of the fluid obtained from the propagation time difference measured by the ultrasonic flow metering portion, the set value, and the pressure measured by the pressure measuring portion with each other when the control portion controls the flow rate adjusting portion.