Experimental study of vortex flow sensors , the test line The device consists of eight standard diameter of DN = 50 ~ 150mm sensor string , the parallel combination with the detection of large-diameter sensor (DN = 80 ~ 300mm) comparisons. Test line parallel diagonal direction , its purpose is to save raw materials and reduce the cost, but also just to meet the requirements of various calibres sensor front straight segment ( according to national standards or regulations ZBN12005-1989 JJG643-1994) before the standard sensor straight pipe segment grew and 50DN; being straight pipe before detection sensor longer than 20DN; so resistance losses to a minimum.