Bill Ory of Bill Ory Engineering had been enlisted to advise on problems experienced with a Texas plant's induced fan oil cooling system. Bill started by building an AFT Fathom model of the cooling system consisting of 130' of 1-1/2" sch40 steel pipe, numerous bends and valves and the oil cooler. While the model verified the design should deliver the required cooling water flow of approximately 45 gpm, field data in conjunction with calibrating the model to this data indicated the cooler was only receiving about 14 gpm. Inspection revealed the problem to be caused by biological fouling in the supply piping.

When asked to quantify the extent of fouling by the plant operators, Bill provided two real world comparisons; one, what additional length of 1-1/2" pipe would cause this reduction of flow and two, what equivalent size of tubing at the original length would have the same effect. In the first example the line length of 1-1/2", clean pipe would have to increase from the actual 130' to 8,850' to cause this magnitude of flow reduction. Alternatively, the supply line would have to be reduced from a 1-1/2" pipe to 16 BWG tubing between 5/8" and 3/4" OD. These examples provided those with less hydraulics knowledge than Bill a real world indication of the magnitude of the fouling present.

This is an example of one of the many benefits of piping system modeling. Once developed, modifying the model to make investigations likes this is both easy and quick, and since AFT Fathom accurately models the interdependencies of all the components, the system wide effect of changing any variable is automatically captured.