One problem that Palmer-Bowlus Flume's have is the collection of sediment upsteam of the throat ramp.  When flows contain dense sediments, these sediments can deposit out upstream of the throat ramp.  For this reason, care should be taken when applying the Palmer-Bowlus Flume to industrial applications where sand, gravel, powdercoating shot, glass, or metal shavings may be present.  Over time these sediments can build up to the point where they affect the accuracy of the flume.