Which of the following are major components of the air supply circuit?
- Drain valve
- Safety valve
- Air dryer
- All of the above ✓
Answer: D. All of the above
All three listed parts—the drain valve, the safety valve, and the air dryer—are major components of the air supply circuit.
Why this is the answer
The handbook treats each of these as part of the air supply side. It describes the safety valve as protecting the reservoirs from overpressure if the governor fails to unload the compressor. It says drain valves are fitted to all reservoirs so water and sludge can be removed before they contaminate valves. It also describes an air dryer with a purge port that ejects contaminants and notes the safety valve is often installed at the dryer. Because all three appear as air-supply components, the all-of-the-above choice fits.
Why the other answers are wrong
- A. Drain valve — A drain valve is one air-supply component, but choosing it alone leaves out the safety valve and air dryer.
- B. Safety valve — A safety valve is one air-supply component, but choosing it alone leaves out the drain valve and air dryer.
- C. Air dryer — An air dryer is one air-supply component, but choosing it alone leaves out the drain valve and safety valve.
Remember it
Think of the supply side as three jobs: dry the air, release excess pressure, and drain the tanks.