I need Expansion Volume

[iminsincere]

Input Data

1) System total hot water volume = 1,300 cu. meters (Including pipeliens & boilers)
2) Boiler Design Pressure = 200 psig
3) System Pressure = 10 bars (145 psig)
4) Water Inlet to Boiler = 140 deg. C
5) Water Outlet from Boiler = 155 deg. C

What will the total volume Expansion to Desing Expansion Vessel?

[Brian_UK]

I don't know, what is the correct answer please?

[Yuri B.]

(wrong forum wrong name?) Only it seems to me water at 155 C should have a much greater (absolute) pressure. Who would agree?

[Entropie]

You have to look onto a pressure / saturation temperature chart for water to find the correct answer. If the system pressure is to low the water will start to boil. The system pressure has to be choosen therefore with some safety margin, because you may experience pressure losses due to hydraulic friction.

[Yuri B.]

The poster was not quizzing the forum, he seems to have needed an expansion tank for the system he described and whether somebody can hint in the direction of some - however rough - a calculation formula.
I am interested in so much as ignorant on that subject too - just wanted to check my intuition prior to finding a pressure/temp table for water.