This standard provides the specification and installation of bend meters used as primary elements in the measurement of clear, single phase, incompressible fluid flow. Accuracy of this measuring device depends upon the sharpness of bend and the velocity of flow, elimination of entrapped air in the upstream which is an essential condition, and on periodic calibration as no reliable data exists on the influence of roughness of pipe and the Reynolds number of Row for the coefficient of discharge of the meter. This device is not recommended for use in very sharp bends
with R/d ( radius of curvature to diameter of pipe ) ratio less than 1.25
and velocity less than 1 m/s.
IS 9115-1979 history
1979IS 9115-1979 Method for estimating incompressible fluid flow in closed pipes using bend gauges