Abstract:In order to solve the problem of poor linearity of laminar flow meter, a micro gaptype laminar flow meter is proposed. The measurement principle, structure design and parameter calculation of the laminar flow meter are introduced in this paper. A gaptype LFM with a designed flow range of 0~280 mL/min was tested, the used standard equipment was a standard piston device. In the test the combined uncertainty is 012% and the extended uncertainty is 024% (k=2). The test result shows that under the premise of not using any correction factor the maximum reference error of the tested device is -090%, which means that the LFM under test reaches the designed specification: accuracy of 10 class with a flow range of 10∶1. In addition, the tested LFM has a good linearity, and the value Remax de/l is 342 that is greater than the traditional required value of 2~25, which indicates that this structure design can effectively overcome the nonlinear influence caused by sudden expansion and sudden contraction.