1. Maximum pressure attainable by any liquid is saturation vapor pressure. Saturation vapor pressure is the pressure exerted by vapor above the surface of liquid when the air has become saturated.

2. Initially when vapor is being injected at a uniform rate the pressure inside the chamber will increase.

3. But after a certain limit air inside vessel will become saturated and then if we add more vapor to air it will condense.

4. At that point pressure will stop increasing and will become constant as pressure has reached the value of saturated vapor pressure.

So, pressure will increase first and then will become constant.