Expansion Tank Location
Expansion Tank Location
(OP)
Where is the best location of expansion tank for chilled water system if the building is multi story around 100 meters high?
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RE: Expansion Tank Location
RE: Expansion Tank Location
RE: Expansion Tank Location
I totally agree with imok2 that the correct location for an expansion tank is at the suction of the pump... however in a tall building the tank will be much smaller is located at the top of the system. How much smaller (and if it is worth it) will be determined by sizing both scenarios.
Having said that, you need a place at the top of the system to locate the tank.
RE: Expansion Tank Location
I suggest you to read the excellent article Understanding Expansion Tanks by Steven T. Taylor appeared in March 2003 edition of ASHRAE Journal.
RE: Expansion Tank Location
RE: Expansion Tank Location
RE: Expansion Tank Location
RE: Expansion Tank Location
The pump suction pressure equals the static head available at the pump suction - the frictional losses in the suction piping at the given flowrate. Now, start from the pump suction and trace back the suction line. At every position, the static head decreases as the elevational difference is reduced and even the frictional losses get reduced (as the pipe length is shortened).
So, at some point, the difference becomes zero (in the absence of an expansion tank and if you ignore temperature effect on the fluid) and this is your low pressure point. Most probably, this point will be where the suction pipe takes a downward turn towards the pump.
Generally, when we design a pump for closed system, the static head is considered to be zero and only dynamic head +pressure drop across equipment is calculated. This may indicate that, as the length of pipe increases, the pressure drop increases and so, the pressure will be the lowest at the pump suction. This is a wrong assumption as the pump pushes the fluid against a static head in the discharge leg and suction static head supplements the pump.
Hope I tried to answer your question.
RE: Expansion Tank Location