Now, for the disadvantages: rangeability, or turndown is limited to about 1:5 for reasonable accuracy; the fluid should be clean and non-condensing; pressure drop can be significant for some systems, such as fans or blowers (limiting dP to ~ 5 IWC); flange tubing can leak, plug or corrode more easily than pipe; orifices can be eroded with time; the slow responsiveness of the diaphragm and fill mea