pump head vs pipe pressure in high rise building 5

[carlanox]

Hi all,

I am a new engineer, just started to work. I have a debate regarding the pressure in the chiller closed loop system.
So here is the case:
1. Building height is 110m, as in the vertical pipe height
2. We are using 3 pumps in parallel (2 running and 1 backup) with each pump has 40m head, located in the first floor

So what is the pressure reading on the first floor when
a. no pump is running
b. 1 pump is running
c. 2 pumps are running

and here is what i think.
a. since height is 110m so pressure reading in the bottom is 11 bar, assuming 10m is 1 bar
b. with 40m head pump, the pressure will be 11 bar (gravity) + 4 bar (from the pump head) so total is 15 bar
c. depending on the pump curve, it will be 11 bar + 4 bar + 2 bar assuming 50% for the pump series effect so total will be 17 bar

please advice on my answers. thank you

 

[ProcessHVAC]

Most of your questions have been answered, but just out of curiosity, why an open tank? Can't think of any advantages

 

[milena0208]

I think the option would be "water heater expansion tank" , water cooling in this case.

But it if get damaged, a open tank will never fail, at last if the refill valve do not close, overflow is the only problem.

 

[carlanox]

but just out of curiosity, why an open tank? Can't think of any advantages

what is wrong with open tank? it is used to top up water in case there is space or air in the system

 

[moideen]

The discharge head pressures of GBTorpenhow and SAK9 are said to be 13 and 15 bars, respectively. I believe the correct digit is 13. Also, GBTorpenhow said there were 14 bars when two pumps worked parallelly; he added 1 bar. Why put more pressure on Will the pressure be the same if only one pump is used or if two pumps are used together?

The problem with the world is that intelligent people are full of doubts, while stupid ones are full of confidence.
-Charles Bukowski-

 

[GBTorpenhow]

The discharge head pressures of GBTorpenhow and SAK9 are said to be 13 and 15 bars, respectively. I believe the correct digit is 13. Also, GBTorpenhow said there were 14 bars when two pumps worked parallelly; he added 1 bar. Why put more pressure on Will the pressure be the same if only one pump is used or if two pumps are used together?

It's a closed loop, so with two pumps running, the increased flow gives more system resistance so the pump developed head increases. See the diagram linked in OP's 9 Nov post above.

The numbers stated are illustrative only, the pump curve and system curve have apparently since been provided so the operating points with one and two pumps running can be determined if desired.