I converted some of my structured text routines to CLX Add-ons. If anyone is interested I would be happy to share. They are tried and true routines that I've used for years. Both are used for calculating flow through an orifice plate. Gas Routine: It follows AGA7 but does not include a calculation for a live NX19 z factor (if you don't know what that is then you probably don't need the add-on). I've compared it to TotalFlow's and Fisher ROC's and while I wouldn't use it for custody transfer it's very good for plant or system balancing. If you understand gas measurement then you'll understand the required inputs. Personally I map the input values to the tag with structured text and then lock the routine with a password so someone doesn't screw something up. Inputs: Atmospheric Pressure, Pressure Base, Temperature Base, Pipe ID, Plate Bore, Inches of Water, Flowing Pressure (PSIG), Flowing Temperature (°F), Specific Gravity, Z factor, Cp/Cv, Nitrogen Mol %, CO2 Mol%. You can set the last two to zero if you aren't correcting for btu Outputs: SCFH, MSCFD, MMSCFD, and #/Hr as well as Beta Ratio and the factors used to calculate flow through an orifice (Fr, Fgr, Fpb, etc) Liquid Routine: This is a much simpler routine. The result is extremely accurate if you feed it good data. The routine requires you to know, or at least guess accurately , what the flowing specific gravity of the fluid is as well as the specific gravity at 60°F. For processes that have widely varying temperature (for instance a hot oil heater. On cold startup the oil is 60 - 100° but when running it can be as much as 350 - 600°. The specific gravity of the oil varies significantly between the two conditions) I use a function generator (10 x and y data points) set up with specific gravity for the range of operating conditions. Neither routine requires the user to input factors. Inputs: Pipe ID, Plate Bore, Flowing Temperature, Specific gravity@ 60°F, Specific gravity@ flowing temperature °F, inches of water differential. Outputs: GPM, BPH, and #/HR (plus all of the intermediate calcs like Beta ratio, etc)
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