expansion tank placement

[kdashc]

Where are expansion tanks typically placed in a closed system? hot side or cold side? any one have good rules of thumb for placement of diaphragm expansion tanks in a system containing a pump, heat source, and heat exchanger?
thank you.

 

[vpl]

hot side

see for example:

http://www.ap600.westinghousenuclear.com/images/NSSS_diagram.jpg

Patricia Lougheed

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[kdashc]

I've seen some references saying the cold side since it has a lower pressur and installing on hot side shortens life of diaphram expansion tank???

vpl? do you know reasonings for the above placement?

 

[vpl]

In the system shown in the drawing, I believe the reason is to maintain a constant pressure in the system. And, tbh, the expansion tank shown is not a diaphragm expansion tank.

Unfortunately the agency website -- that shows all the various permutations where expansion tanks are used -- is currently off-line for maintenance. So I can't readily find other examples.

I'll poke around, but it'll be a bit. I'm kind of busy today.

Patricia Lougheed

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[ione]

Installing the expansion tank on the supply side at the lowest pressure point should reduce the size of the expansion tank. Take a look to the link below to collect further useful information

http://www.taylor-engineering.com/d...nderstanding Expansion Tanks-Taylor Proof.pdf

 

[kdashc]

anythoughts on the relation to the pump? ie discharge or suction side?

 

[micalbrch]

That depends upon the pump. A simple sketch of your closed system would definitely help. Hot side makes the tank more expensive. That's for sure. But gas (with or without diaphragm) expands at higher temperature. That must be considered, too. So, I guess there is no answer for all possible systems but it must be checked what the best installation point for your system with your pump is.

 

[CH5OH]

the size of the expansion tank is defined by the amount of expansion required.this depends on max and min temperature and the volume of the liquid:
high level-low level expansion tank=volume liquid on maximum temperature-volume liquid on minimum temperature

if the suction of the pump is connected to the bottom of the tank (liquid header) the system can be vented on the highest points (after the pump, simply by running some small diameter pipes to the top of the expansion tank.

when connected in such way (liquid header)the pressure requirements for the header tank (or elevated height in case of atmospheric tank) is the lowest.