The on the spot inspection of natural gas orifice meter is adopting the transitivity calibration method taking Venturi nozzle as calibration scale.
天然气孔板流量计的现场检定，采用以文丘里音速喷嘴作为标准表的传递型校准法。
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This article discusses the method and accuracy for header differential steel nozzle fillet magnetic particle inspection, and shows the actual dissection result that the author did on products.