Elevation Calculation in Sizing Mainline

Steve,

Please see my interpretation (attached for your review) of what you are explaining.

I have:

• My meter with a spot elevation of 100' next to it
• My valve with a spot elevation of 80'  next to it
• My heads with a liberal amount of 120' spots, just to make sure the system is picking the furthest head and the appropriate spot elevation at that point

I sized my laterals and made sure to pick "Use Spot Elevations". I then sized my mainline making sure to pick the "Use Spot Elevations" option there as well.

Running a Valve Schedule, I can pick the Elevation option and see that for this valve i have a Head elevation of 40' (difference of 120' and 80' spots) and I have a valve elevation of -20 (difference of 80' and 100' spots).

If you were to run the Critical analysis, you should see the mainline calculation breakdown, including the spot elevation numbers. And if you were to use the edit equipment tool and click the valve, you should be able to click on the analysis button there and see the breakdown with respective elevation loss for the heads.

Please let me know if I am missing anything and we can go from there!

Jake,

This was a user error (again). The laterals were sized without having the "Use Spot Elevations" clicked. This is a real eye opener for me from a QC perspective. When I see that the critical analysis shows a gain from pressure due to being lower in elevation than the meter, it would be easy to assume that there is enough pressure to run the system. But if the laterals were not run using spots, it is providing faulty information that is not detectable through the Critical Analysis Report. - This makes me a little uncomfortable. Maybe a notification similar to the "Some valves are not connected. They are shown in yellow. Continue?" . That would be helpful. 

Suggestion: If the user clicks the box to use spot elevations to calculate mainline size, the program should check the valves served by that mainline. If the pressure change due to elevation change for the valve was calculated as 0, the program could provide an alert such as "Some of the valves served by this mainline may not have been calculated using spot elevations. They are highlighted in yellow. Would you like to continue?"

This would make me feel more comfortable. Don't you want to make me feel more comfortable?

Seaweed,

You always give great thoughts, and you know I want you to be the most comfortable ;).

I like the idea of somehow making it more visible to the user when sizing laterals that they may have forgotten to check the "Use Spot Elevations" option.

I will tell you that this is exactly why you should be using the Valve Schedule as a QC tool as well. You will see at a glance for every valve on that project, that was sized/not sized, to what their elevation values are. If you see a valve that shows a 0 elevation, you know it wasn't sized using spot elevations. Further, you could then use LOCATEVALVE to jump over to that valve, resize that lateral and then resize your mainline.

I will, however, talk this idea over with the team and see what we can come up with. Thanks for your suggestions!

Cheers,

We do run the valve schedule when we're done, but when we're in the design process, we use the table that pops up when one sizes the mainline. My point is that sometimes unintentional misleading information may be worse than none at all. For instance, in this situation the table shows more than enough pressure since it's gaining so much head as it goes down hill to the valve. But there may not be enough pressure to operate the system as the water goes from the valves up hill to support the emission device(s). Speaking of that. Do the pressure readings only go to the pipe transition point when serving a drip system? It doesn't appear to be reading the spot elevations beyond that as the emitter tubing continues to climb the slope. And I know, If I'm climbing higher than my CV holds I should be using another  transition point with a swing check valve, but even at that I'm climbing 8.5' (Techline HCVXR) which takes another 3.7 psi to serve. - I hope that my idea of an alert catches on. It can be just as important as a valve not being connected. And I don't think that it's reasonable to run a valve schedule before one sizes the mainline. It's not our workflow now anyway. I always appreciate your suggestions Jake!

Seaweed,

Thanks for the phone conversation earlier today. I talked with Jeremiah about what could possibly be done with including a message alerting the user that certain valves may not have been sized while using spot elevations. As usual, he has a great idea that might make this all be a thing of the past...what if the system simply sized the laterals or mainline using spot elevations automatically if it finds spot elevations in the plan?? That way the possibility of a user forgetting to check the "Use Spot Elevations" option will be removed from the equation. 

Past this, there may also be a way to put a little "Used spot elevations" indicator next to the elevation column in the Valve Schedule, so you could do a quick glance and see that all valves have been sized as desired.

Let me know your thoughts and I will get something marked down in our wishlist vault ;)

Well Jake, of course Jeremiah will find a logical solution. I like the idea a lot. How would this help though if the laterals were sized prior to adding spot elevations such as the drawing that I'm working on now. We didn't know that the pressure (or lack of it) would prove to be so challenging at first. We had the laterals already designed and sized (without spots).

I still like the idea of somehow coding the valve with data representing the pipe sizing with spots or not. And then posting an alert if the user is sizing the main using spots and the worst case valve was not sized using spots.

But no matter what, I'm quite aware of the issue now. Too bad for those that don't and make the mistake that's not detected until after construction. The heads (or other emission device) does not operate. If it's gotten that far, the solution will be to add a pump. If known sooner, many options would be available like they are to us now (since we know about this potential ________). I don't know what word to use. Issue? Flaw in reporting due to omission? Lack of user knowledge? Whatever the word, it's not good.

Our workflow now will include resizing all of the laterals then mains using spot elevations before running a critical report. I suppose we'll have to use the valve schedule more often too. I consider these work-arounds though until the wizards add the alert pop-up. :)

Thanks to you and Jeremiah. - Seaweed