Bridge unicellular orifice flowmeter, it contains a straight pipe, said straight pipe mounted orifice are respectively provided on both sides of a straight wall of the orifice of a measuring tube, the straight tube and a bridge pipe parallel connection, both lumen interconnected, and said straight tube and the two connection points of the bridge pipe are located at the outside of the two measuring tubes, and said bridge tube is installed on a hoist control valve. The simple structure, reasonable design to address the effects of the throttle reasons for the losses caused by the negative pressure of the coal mine gas drainage system, effectively improve the gas drainage; wide scope of application, easy to spread, with good social and economic benefits Our main producing mining "one through three anti products, mainly FBQ series of water-sealed explosion-proof, water-sealed explosion FHQ series of anti-tempering device FBFH series binoculars, FFQ series of anti back fire anti-back gas device, FFFQ anti-tempering anti backwater anti return air device the series differences FBQF type explosion-proof, FZQ series gas drainage piping slagging, FZQ-K-type gas drainage pipe fast slagging FKL series orifice plate and orifice flowmeter, automatic slagging APS-FY-type negative pressure drainage, CWG-FY-type negative pressure automatically turn on the water is the CWG-ZY type the barotropic automatically turn on the water is KDP21 type negative pressure row slag turn on the water, gas, gas water separator, quality assurance, service warm welcome people to inquire