3 replies to this topic

[Bill B]

I have been doing a bunch of RV piping calcs, and have been using an entrance "Crane" factor of .5 as a velocity head. I have encountered more than a few situations wherein my inlet dP is slightly higher than 3% with the RV connected directly to the protected vessel. So to solve this I am needing to replace the valves with smaller ones, and add a second nozzle/RV.

So I am wondering if there is data available that shows the velocity head to be < .5 for specifically designed nozzles and the like.

[latexman]

K = 0.5 is for a sharp-edged flush inlet. Look at page A-29 in Crane (25th Pringting - 1991) for a table on rounded-edge flush inlets.

[Bill B]

Thanks, that is what I was looking for. Don't know how I missed it! Now the interesting part - determining how much the welds are rounded.

[latexman]

Look at the vessel drawing and specification. What was specified? Did you get what was asked for? Inspect the joint. If credit is going to be taken for rounded-edge flush inlets, I'd recommend the vessel records say that, even if you have to modify the nozzle and vessel documentation. The management of change procedure is a good vehicle for this.