Fig. \ref{633123}(a) demonstrates the performance of the transfer function models in predicting 10 days testing dataset. For greater clarity, the chart is further enhanced in (b). In (a), the shutdown, start-up and transition mode to DLE are accurately predicted by both the first and second-order systems. The accuracy is contributed from the linear operation of the input and output of the valve. Signal spikes also estimated close to the actual operation. With the percentage opening zoomed in to 2 decimal places, it can be observed that the second-order transfer function shows a closer estimation of the actual data than the first- order transfer function. The highest order indicates greater accuracy due to the addition of s 2 in the function for higher resolution estimation. The trend of the actual signal is not precisely estimated into 2 decimal places in (b), but the trend in (a) is adequate to prove model’s ability in representing the pilot gas fuel valve operation.