Piping System Flow Problem

[WT-09]

I have modeled a hydronic supply system with the centrifugal pump. My problem is as follows:
pipe's flow value drops to 0 after the tee fitting. The pipe before the tee has a correct value, but the one after the tee and all the following ones indicate 0 GPM. Everything is connected and in the system.
What am I missing here?

[kyle.bernhardt]

Extremely difficult to tell from your brief description. Screen captures or examples files are the best way to communicate the issue.

This typically results when you have a defined flow in a way that cannot be resolved by our flow engine. Keep in mind that the definition of flow extends beyond the actual flow values, but into the Connectors within your Pipe network, and their Flow Direction and Flow Configuration parameters.

I wrote some blog posts on this a while back, search "go with the flow" on the Inside the System blog.

Cheers,
Kyle B

[DaveDH]

We've had a similar problem, not only with pipe fittings but with duct fittings as well. We still don't know why fittings sometimes drop flow values.

However, recently, we tried using the auto-layout and auto-sizing for a medium sized duct system with about 20 vav's. We were able to get it to work, eventually, by tracking down the errors in the system one by one . . . things like FPM, making sure connectors were right, and specifying other things that I can't remember off the top of my head. We knew the flow accross fittings was propagating because, in the end, we had a working system. I think the reason is that we took the time to track down all the numbers and factors that make up a system. This sounds time consuming and tedious . . . however, it took about two hours for myself and a mech engineer to generate a solid layout from scratch in one shot, instead of the mech engineer sketching out a layout on paper, then me putting it into Revit and printing it out for him to look at and resketch some more etc. Also, we a have system with numbers that the engineer can extract and use. And the next time it will be faster since we know what to look for.

So I guess my point is that the issue goes beyond just the fittings and everything being connected. . . it's making sure everything is complete. Try the auto-layout and auto-size features and look into the errors that turn up and try to fix them . . . and as the errors get ironed out, I think the fittings will start working like they should.


Dave

[kyle.bernhardt]

One other thing to add here, the use of Duct System Family Color Fills is immensely useful in understand the flow state in your duct Systems.

This way you can visually understand where you have defined and undefined flows in your systems.

If you want to see that in action, go open up the Urban House MEP dataset I posted to Inside the System a couple years back. You are free to poach the settings from that file into your project using Transfer Project Standards.

Cheers,
Kyle B

[martinnman911528]

Well, there are several schemes have been designed to infer the valve adjustment for measuring flow discharge line. These require that the flow downstream from the tee recycling to be subtracted from the minimum flow requirements. Recycle valve opens in proportion to the difference, if positive.

Submersible Well Pumps

[williamfritz86623902]

Common types of pump used for applications are reciprocating positive displacement pumps, particularly plunger pumps, which are capable of handling applications easily. These pumps are very thorough and are great for several industries, even the cosmetic to give you an idea of one in particular.

[kyleadam]

Tether floats hang freely from the side of the pump. As the water raises so does the float which triggers a switch that activates the pump.Before you install your sump pump, you'll need to decide if you want a cast iron sump pump or a plastic one. Balance out whether or not the money saved on a plastic pump is worth the risk of a flooded basement.