MFI series insertion mass flow meters are designed for gas monitoring and control in a large pipe line where installation of an in-line flow meter is either difficult or costly. The insertion meters are equipped with a self-sealed valve and hence provide a solution that only requires minimal interruption to the normal working circumstance. The suggested starting metering DN is 150 mm and above. All of the insertion meters have an accuracy of (1.5+0.5FS)% or better depending on the requests. The meters can work at an environment of -20 to 60 C and pressure up to 1.5 MPa. Applications include but not limited to oxygen, nitrogen, methane, and compressed air flow monitoring for manufacture process control.