Oilers/Plant Tenders (HHC) Civil Service Practice Exam

When is a gasoline-driven air compressor considered to be unloaded?

1. When it is not connected to power

2. When the inlet valves on the air compressor are held in the open position

3. When the pressure gauge shows zero

4. When the compressor is in standby mode

The correct answer is: When the inlet valves on the air compressor are held in the open position

A gasoline-driven air compressor is considered to be unloaded when the inlet valves are held in the open position. This allows air to flow freely through the compressor without building up pressure in the system. In this state, the compressor is not working against any pressure resistance, which is important for protecting the machinery and ensuring that it can operate efficiently. When the inlet valves are held open, the compressor can run without generating compressed air, making it a key operational mode during various maintenance activities or when the system needs to be tested. This scenario is essential for understanding how air compressors function and the significance of unloading for regular maintenance and safety protocols. The other options do not accurately describe the unloaded state. For example, not being connected to power would simply mean the compressor is off, while a zero pressure gauge indicates there's no air in the system but does not specify the operational state of the compressor itself. Additionally, standby mode typically refers to a state where the compressor is ready to operate but not actively compressing air, which does not precisely align with the definition of being unloaded.