USGS Standard Orifice Fitting, Galvanized

The proper placement of the orifice is essential for an accurate stage record. The orifice should be located where the height of water above it represents the stage in the river. If it is partly buried in sand or mud, the recorded stage will be greater than that in the river. An orifice preferably should not be installed in swift currents. If this is unavoidable, it must be kept at right angles to the direction of flow. A recommended mounting for swift-flow conditions is for the orifice to be mounted flush with the wall of the mounting structure. Care should also be taken to keep the orifice out of highly turbulent flow. Fits on 2" pipe.