A flow meter for measuring a flow rate of a fluid may include a cartridge containing certain components such as a flow sensor. The cartridge is removable from the flow meter such that it may be replaced with a new cartridge, allowing calibration of the flow meter while enabling the flow meter to continue to be operated with another cartridge in the place of the removed cartridge. The flow meter may be configured to direct fluid flow away from selected components of the flow meter.

There is provided a substrate processing method in a substrate processing apparatus including a gas supplier that vaporizes a raw material in a raw material container and supplies a raw material gas together with a carrier gas, including: calibrating a relational expression between a flow rate of the carrier gas and a flow rate of the raw material gas; and processing a substrate in a processing container by controlling the flow rate of the carrier gas based on the relational expression and supplying the raw material gas into the processing container, wherein, in the calibrating the relational expression, the relational expression is derived by allowing the carrier gas to continuously flow.

A flow meter for measuring a flow rate of a fluid may include a cartridge containing certain components such as a flow sensor. The cartridge is removable from the flow meter such that it may be replaced with a new cartridge, allowing calibration of the flow meter while enabling the flow meter to continue to be operated with another cartridge in the place of the removed cartridge. The flow meter may be configured to direct fluid flow away from selected components of the flow meter.