Close loop charging 3

[saeedplc]

Hi dear experts,

Dears i am very new to mechanic knowledge and my below question maybe seem very simple to answer but are very tough for me to get.

Could you please let me know what pressure amount shold a close secondary loop of a chilled water be filled to? For instance a loop can be charged up to 2 or 3 bar or everything. What determine the right pressure?
Should the loop be precharged with water when the valves of the equipments are open or close or in working condition?

designer of the system has mentioned duty point of the pump as 130m3 1.7bar.
The duty point is when the equipments are in their full flow or their working conditions?

Regards,

 

[saeedplc]

Thank you for the response
So as an example if the highest point above the pump is 5 meter the pressure for charging the loop should be almost 0.5 bar plus some safety margine. That means about 1 bar
Am i right?

Another question is there any book i can refer to be good at similar subject such as close loops, expansion tank, pumps and etc?

Thanks a lot

 

[1503-44]

You really only need to know two elevations to get 1 distance. Top of pipe and gage, but the pump CL makes a good reference. If your gage was the top of pipe, you'd only need to read it.

Top of Pipe to pump CL, PCL = 5m above pump centerline
Gage to pump CL, GCL = 0.5m above pump centerline
if Gage is above the pump centerline, note that GCL is (+)
Charge pressure barg = (PCL - GCL)/10.34 = (5 - 0.5)/10.34 = 4.5/10.34 = 0.435 Barg

if Gage is below the pump centerline, note that GCL is (-)
Charge Pressure barg = (PCL - -GCL)/10.34 = (PCL + GCL)/10.34 = (5 + 0.5)/10.34 = 5.5/10.34 = 0.532 Barg

Add the fluids (water) vapour pressure, Pv, to the pressure calculated above.
At 20°C Pv is around almost nothing. At 100°C Pv is 1 Bar





A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[saeedplc]

Thank a lot for your valuable response

Could you please answer the second question according to your experience? It is very important to me.

 

[1503-44]

I have a 1983 edition of "pumps & Pump Systems" American Society of Plumbing Engineers. I dont know if there is a newer edition. Its great for general pump system design focusing on building water supply from city water sources, well pumps and tanks, lifting to rooftop tanks, pipe flow, etc. Also very good section on vfd controlled systems. A great all around reference.

I also have the 1992 edition of "Pumps and Pumping Operations". N. Cheremisinoff & P. Cheremisinoff, Preston Hall. Its got more focus on pump technical details, bearings, seal types, optional features and other pump design specifics, and addresses a much wider range of system types, where the other focuses mostly on plumbing and water supply.

Old books, but still excellent for learning the basics and general system design references..

A black swan to a turkey is a white swan to the butcher ... and to Boeing.