of the packing within the mid span packing 18 may be obtained in various ways specifically the measured pressure at the time of the test can be compared to the design pressure to guide an assumption about the amount of n 2 flow the measured pressure during an n 2 inference test can be used to ensure that the test itself is not affecting the sealing surfaces of the turbine the measured pressure ratio between the hp section 12 and the mid span packing 18 over time can be used to monitor changes in the seal clearances in the packing 18 or a constant measured pressure during a time period with a change in ip section efficiency could indicate internal damage that may be opening other leakage flow paths between the hp and ip sections thus the present arrangement can help diagnose performance shortfalls on new units as well as indicate degradation on in service units validation teams can use these pressure readings to conduct more accurate analyses design teams can use the data to verify their assumptions and the commercial team may use the data to remedy any performance shortfalls and to guarantee as well as to identify any areas in an existing unit that may be suited for an upgrade.