Which of the following statements describes...

🔍 Key Concepts

• Pneumatic symbols for a pressure-reducing valve versus a relief (safety) valve • How control air is produced from 30 bar start air and delivered at about 7 bar to the air control reservoir • The relationship between devices B, C, E, F, and the gauge D in this "Control Air Pressure‑Reducing Unit"

💭 Think About

• Trace the air path from the 30 bar start air reservoir through the components to the 7 bar control air reservoir. Where in that path is the actual pressure drop achieved? • Compare the symbol and connections of device C to the symbol and connections of device F. Which one looks like a safety/relief valve open to vent, and which one is clearly in the main flow line? • Ask yourself whether device C serves a special function just for ancillary services, or if it is clearly part of the main pressure-reduction train feeding the control air reservoir.

✅ Before You Answer

• Verify which component(s) are directly in the main flow line between the 30 bar source and the 7 bar outlet. • Check which component is connected so that it will vent to atmosphere only when pressure gets too high (typical of a relief/safety valve). • Confirm whether devices B and C appear identical and parallel, suggesting the same function (e.g., duty/standby), or whether one is clearly a pilot or modifier of the other.

Which of the following statements describes the function of the device labeled "C" shown in the illustration? Illustration MO-0115

The regulator, or pressure reducer, drops the supply pressure to the desired operating level.

Constant pressure is maintained at device "B" while device "C" is used only to modify the output signal.

The regulator reduces the pressure of the supply air to provide ancillary main engine services.

The device is a relief valve with feedback to prevent excessive pressure from damaging system components.

🔍 Key Concepts

💭 Think About

✅ Before You Answer