LFOM Entrance Tank Mathcad Code Documentation

Mathcad Code

The mathcad code can be found here, the code with refernces inserted is also available here. You will need to have mathcad installed on your computer in order to open the file.

Variable Description Table available here.

Challenge Questions

1. How do we determine the number of riser pipes necessary for the plant, currently the code assumes only one riser pipe is necessay?

One constraint on the number of riser pipes is the price variation of PVC pipe as the diameter increases, if the wide diameter price is too high then it would be beneficial to incorporate 2 small er diameter riser pipes. Attached is a price comparison for PVC pipe of varying diameters, link to LFOM PVC Price Comparisons.

Another constraint on the number of riser pipes is the rapid mix design. Curently the alum is dropped directly into the riser pipe as a means of rapid mix and this system performs optimally with one riser pipe.

1. What are the pressures that regulate the dill size used in creation of the orifices and how do we determine the drill size?

Previously trial and error has provided a value of 5 orifices in the initial row is optimal, why? Currently a new method involving integration of the sutro weir equation over various heights is being explored. Discussion of the question is available atLFOM drill size determination

1. How are the riser pipe lengths calculated, should they include the protion of the pipe that is inserted into the pipe fitting?

The discussion of that question is available at Linear Orifice Flow Meter Calculation of Total Riser Pipe Height