Not only is the orifice plate placed much too close to an elbow, the elbow happens to be on the
upstream side of the orifice plate, where disturbances have the greatest effect! The saving grace
of this installation is that it is not used for critical monitoring or control: it is simply a manual
indication of air flow rate where accuracy is not terribly important. Nevertheless, it is sad to see
how an orifice meter installation could have been so easily improved with just a simple re-location
of the orifice plate along the piping length