Hello!
When adding new heads/nozzles to the design I am prompted with setting the Design Pressure for the given equipment. How do I know which one to select when I am not using pressure compensating heads? For my project we are using a 2" water meter with 50 static PSI at the hose bib.
I was using 35 for the PSI, but was worried it might be 40 PSI instead. When I made that change the zones had higher GPMs, which made me redesign the system.
What's the best way to figure out the correct PSI from the beginning? Thank you!
Grant,
It seems that you have added the Source Pressure correctly, assuming that 50psi is what you will have when tapping into the mainline.
When you are adding the equipment to your project, the design pressure you are setting is going to be for what you anticipate your heads to operate at. Typically you are thinking about what your last (furthest) head will need to operate. So, in your case it sounds like setting to 35psi would be fine (assuming you want those heads to run at 35psi). The system will then calculate and add up the rest of the friction and fitting losses through the laterals and valves to get what each valve will need (past the head operating pressure).
Once you have sized your laterals and mainline, you can always check your residual pressure to ensure you have enough left over as a buffer for any other concerns you want to account for.
If you have further questions or if I have misunderstood what you are after just let us know!
Jake,
Thanks for the help with my last question. I have another one.
After sizing the lateral and mainline is there a place where I can see the actual head pressure for specific heads in a zone? That way I can double check that I am using the right design pressure for the heads.
The last program I was using it showed the actual head pressure for each head. Is there something like this in this program? Thanks!
Grant,
To ensure you are using the right pressure for the heads, it would be wise to assume the need of pressure regulating heads in your design. In fact, it is a frequent requirement to implement pressure regulating equipment in certain jurisdictions.
As to where you can see how you have set things up- If you run a Valve Schedule, you will see a few numbers that will give you a snap shot at how each valve is set up. Design pressure, which is what the equipment will operate at. PSI shows what the pressure required at the valve is, and PSI @ POC which is pressure required back at the start of the system.
As Tom pointed out, you can use the Edit Equipment button and click any section of pipe to see the pressure requirement at that given point. Remember that this will be the design pressure of the head and the friction loss for that pipe segment based on total flow coming through that pipe.
We just need to remember that all the system is doing is working from the furthest head, back to the valve (just like you would be doing manually). The system is not pushing water out to the heads when designing (other than when using a System Monitor).
I am happy to chat with you about any of this further if you would like. Feel free to shoot us an email at
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