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QualityTime, Sorry I forgot to mention that I'm in a subbie doing piping job for the contractors. We just provide budget for our client the contractor to estimate the cost impact of different designs.

Budgeting. In fact, some of project are won by the contractors based on their preliminary design, because compared to the consultant engineer's design, the contractor's design is cheaper. (for example, water-cooled is changed to air-cooled; water-based changed to refrigerant; etc) I know the...

Thanks QualityTime, Thank you for explaining what's system curve. Gosh I should have asked earlier, instead of staring at it a whole morning.

Hi QualityTime, moideen, Sorry gents, my question must have caused confusion and data is cockeyed. That's partly because that project I looked at was at a preliminary stage. This is the doc I've received from my client. There's no schematic available. The only schematic available for the...

Thanks QualityTime, 1. Yes I should include it in calculations. I got puzzled this morning because I was trying to fit velocity head into bernoulli principle, where the water already has a velocity/momentum. And I couldn't. Now I think velocity head is, when the pump starts up, what pushes...

moideen, Thank you for recommending mcquay software. I've downloaded their free Pipe Alator excel sheet. It's very handy. And the sheet's got custom formula, which is a new useful trick for me.

Thanks QualityTime, I can't figure out. But velocity head difference is not huge compared to friction loss. I think as an amateur I'll just leave it out of consideration. Yet another question... if we have a close-loop system served by a pump with 4" discharge running at 400 gpm (10.1 fps)...

Thanks QualityTime, If I have a close-loop system with X ft friction loss, and the pump has a 6" suction and a 4" discharge running at 400 gpm, which calculation is right? 1. Total Dynamic Head = X + 0.31 ft - 1.58 ft (my bet) or 2. Total Dynamic Head = X + 1.58 ft - 0.31 ft

QualityTime, Thanks! I think I've got a rough idea how to estimate friction loss now. You also mentioned "difference in velocity head between the pump suction nozzle size and the pump discharge nozzle size". I don't understand how pressure head transfer into velocity head. I've found some...

Please assume the flow rate has been balanced to be as below (just in case longer run doesn't make the bigger friction loss)

Thank you QualityTime, LittleInch, So when we calculate the total friction, we only need to consider the run with highest friction loss? For example, to get the total friction loss of below, I only need to add up the friction loss in the blue path?

QualityTime,moideen,LittleInch, Yeah thank you very much. I'm digesting what you said. I think I understand most of your info, except what LittleInch means by "design for that as the pressure loss and then add up the flows from all the units". I'll draw up something and try to clarify that...

QualityTime, Yup now I got that static lift is 0 because it's a close loop system. But I've got questions about how to calculate pipe friction loss of the whole system. In below sketch, which is the right way to calculate friction loss? 1. loss in Chiller plant + 50 ft/100 ft x 4.67 + loss at...

QualityTime, Thanks a lot. I'll study it after work. Gosh, now I need a break from work to breathe.

QualityTime, I'm just trying not to ask something stupid that already has its answer in the tech data.

QualityTime, I'm still trying to digest the tech data you gave me. It surely is a lot of info for me to dig into... Thanks a lot.

QualityTime, By the way, this design is done by the contractor. So if it's really a boo boo, you've got another one in your example pool. Although I reckon you don't need any more...

EnergyProfessional, Thanks for the info. That surely sounds a good point for me to start.

Talking about contractor doing the design, I've seen some cases where contractor took on the task because they know cost better. Sometimes their design may achieve some saving in construction cost (maybe not in running cost, I don't know). One case was the consulting engineer got a design with...

QualityTime, Yeah surely possible. This happens as often as I think, because I'm struggling with errors by the consultants in drawings & specs all the times. And I'm not sure how much pain my errors are causing downstream... Thank you so much for sharing your knowledge and experience sir...