Abstract: The present application provides a method of evaluating valve tightness in a turbine by a data acquisition system. The method may include the steps of receiving a number of operating parameters from a number of sensors, opening a first valve and closing a second valve, closing the first valve, determining a pressure decay time between the first valve and the second valve, determining a stable value of pressure between the first valve and the second valve, comparing the pressure decay time and the stable value of pressure to predetermined values, and altering one or more of the operating parameters and/or initiating repair procedures if the pressure decay time and/or the stable value of pressure is increasing and/or exceeds the predetermined values.