A rate-of-change flow measurement device is provided including first pressure sensor, a position control valve with a valve position sensor, a second sensor position and a chamber comprising a part of the flow path of the device, and an isolation valve, arranged in this order along the flow path of the device. The device receives valve position data from the valve position sensor and pressure data from the pressure sensors, and calculates a volume of the chamber at least in part using the valve position data when a calibration of a device-under-test is performed by decreasing a pressure of the chamber or increasing the pressure of the chamber while opening the position control valve to maintain the pressure reading of the first pressure sensor constant to stay at a pressure set point.