System Working Pressure in Chilled Water System

Pump head can be 1 bar but system working presssure can be 5 bar.

Every 27 in w.c / 2'-3" = 1 psi , Convert your pump head to bar, Then calculate all frictional losses of your pipeline add them to your pump head yo get the system working pressure or the cutoff pressure of the booster pumps/pressurization unit,

I am still confused, Pump head is = total frictional losses in the longest circuit of chilled water line. If I add, friction losses in pump head that means system working pressure will be just double of pump head. Am I right?

Can you explain me with example,

Total friction in longest circuit 174.4 feet = 5.21 Bar

Pump head with 10 % safety 191.8 feet = 5.73 bar

Total system working pressure = 5.73 + 5.21 = 10.94 Bar. Is it right.

"I'm a design engineer working in the UAE"?

Who employs you?
If it was me I'd want my money back.

Is this a homework question or just interest?

How to you expect me to comment on 11 bar when you are the designer and you are the engineer? To me TonyS is right.

Frankly you have no previous working experience of working on a pressure boosting system. can you imagine what can happen to anyone opening the "muslim shower" at the wash rooms to wash his ass!! He will have both his balls blown off.

To site my industrial application examples: My pump head was 1.5 bar, my machine requirements were dictated at 3~3.5 bar, my system pressure was 4 bar. It caters the machine part while water Prvs installed on low pressure mains to wash rooms and utilities to stay below 0.6 bar. Each engineering and designing takes over 800 man hours before final selection of Boosting Vessels/Pumps.Sorry I cannot comment on your system.

Suggest you discuss this further with your Supplier. When they sell this system they have a team of engineers to do all the engineering and selection.

"Rule #75".

(Thanks Lynlynch)

When the system is fully charged, the maximum pressure will be at the pump discharge. This will include 1) the vertical height of the water loop, 2) any additional pressure into a bladder tank or the like, 3) pressure drop through control valves, 4) pump pressure needed to overcome pipe friction, and 5) a safety factor.

After the system is charged, the circulating pump head consists of (3), (4), and (5); the other items cancel each other. However, initial charging of the system may require a higher pressure temporary pump to overcome the vertical height and to pressurize the bladder tank.

The pressure drop through control valves should be on the order of 5-10 psid. Pipe friction loss should be similar, and certainly not as much as 170 feet.

Perhaps you should contract the services of a consulting engineer who specializes in this field, and thereby limit the damages of the inevitable lawsuit.

Hi Mr. Aziz,

System working pressure is estimated 25 percent higher than the pump head. The pump curves show that at peak level, that is the best efficiency. For further information, you can search ebara or grundfos.

(MOHD YUSOF)

Since it seems that the Chilled water circuit is a closed circuit and is going to be pressurised, the pump will be considered as a circulating pump capable of creating enough head pressure to overcome the Chiller's heatexchange friction loss (Stated by the maker and ~ 0.5bar at least), plus all the pipework and valves friction losses at the specified flow volume required for the chiller ... All this is to guaranty the necessary flow for the chiller and does not increase the overall pressure of the system (more details required to explain fully...): For your question, the system pressure is the pressure at which the closed circuit has been charged prior to starting the pump, and this must be nough to fill the whole system to the highest point, draining the air from the circuit. Then remains the expansion vessel necessary for such a system, which will be pressurised at a higher pressure than the highest point in the building. The system pressure should not exceed the chiller's recommended maximum pressure or the lowest rated item in the circuit. To work this value accurately, you need more details and knowledge. The supplier can usually help if you supply all the required data.