Steam Condenser

ashutoshd

I am a 2nd year mech engg student. I have a basic doubt in condensers. The steam from turbine exhaust enters the condenser & gets condensed during which its specific volume decreases resulting in formation of partial vacuum. Now according to rankine cycle the process in a condenser is a isobaric & isothermal one(shown by a horizontal straight line coinciding with lower isobar in T-S diag) so if pressure remains constant how is vacuum formed during condensation? I mean shouldnt the pressure decrease too?
This could be a silly question but i have scouted the web but couldnt find any page dealing with this in detail apart from cursory explanation. Any urls explaining this in detail are welcome.

russ_watters

Why do you think a vacuum forms?

ashutoshd

I read it in some books and many places on the net that a partial vacuum is created by virtue of great difference in specific volumes of steam & the condensed water. Is it wrong?