A transparent rigid container is filled with 2 gallons of wa

A transparent rigid container is filled with 2 gallons of water. Initially the pressure is measured to be 10.2 psig, using a gage attached to the container. The local atmospheric pressure is 14.8 psia. It is observed that the liquid water in the container occupies two percent of the container volume. The water in the container is heated. Determine the reading on the pressure gage in psig when all the liquid has just turned to vapor (all saturated vapor). Show this process on a sketch of a T-v diagram

Solution

The density of cold water is 62.4 lb/ft3  

The density of the saturated vapor is 1/50 of the density of the water.

Calculate the density of the vapor and its specific volume.

The density (mass/volume) of water vapor is 0.804 g/l

Look at the saturation table for water/steam and find the temperature-and-pressure that has that density (or specific volume, depending on the table you are using)

Subtract 14.8 from this saturation pressure, which will be absolute, to find the gauge pressure.