A step change from 15 to 31 psi in actual pressure results in the measured response from a pressure-indicating element shown in Figure.

(a) Assuming second-order dynamics calculate all important parameters and write an approximate transfer function in the form, where R? is the instrument output deviation (mm), P? is the actual pressure deviation (psi).

(b) Write an equivalent differential equation model in terms of actual (not deviation) variables.

K R'(s) P') 2 + 2rs + 1 12.7 11.2 R (mm) 2.3 Time (s)