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