A control system in which the flows of fuel and air are precisely measured and adjusted so as to always be in the correct proportions is called ______ control.

• A. Proportional
• B. Proportional-Integral
• C. Metering
• D. Regulating

Answer: (C)

The concept here is metering control. In this approach, the flows of fuel and air are measured precisely and adjusted to stay in the correct proportions, ensuring the combustion process receives the right air–fuel ratio for efficiency and safety. Metering emphasizes the act of measuring and regulating the exact amounts flowing through the system, so the ratio remains as intended even as operating conditions change.

This is different from proportional control, which adjusts output based on error at a given moment but doesn’t inherently enforce the correct air–fuel proportion between two streams. Proportional–Integral adds accumulation of past error to correct steady-state discrepancies, but again, it’s a generic control strategy rather than the specific practice of metering the two flows to maintain the proper ratio. Regulating is a broader term for maintaining a variable near a set point without implying the precise measurement and simultaneous adjustment of both fuel and air flows. Thus, the best fit for maintaining exact proportions of fuel and air is metering control.