|MadSci Network: Engineering|
Dear Mark: I can think of only one reason for your observations based on your description of the turbine operation. The gauge which reads the pressure (or vacuum) in the condensor must not be an absolute gauge, but one which reads the pressure difference between the atmosphere outside and the pressure inside the condensor. So when the atmospheric pressure goes down the gauge inside reading the vacuum reads less because the difference in pressure between the vacuum and the atmosphere has decreased. To avoid this confusion you would have to make a corrction for the change in atmospheric pressure. Since the atmospheric pressure gauge reads the true absolute pressure, you should subtract 1000 from the atmospheric pressure reading; and then subtract that number from the reading of the condensor gauge to get the true pressure in the condensor. I hope this clarifies things for you. R. Bersin.
Try the links in the MadSci Library for more information on Engineering.