Question 13 QMED03 - Oiler

The Correct Answer is C ### Why Option C is Correct: **C) hydrostatic pressure of the expanding liquid** Overfilling a refrigerant container means that the container holds too much liquid and not enough vapor space (headspace). When the temperature of the liquid increases (even slightly), the liquid refrigerant begins to expand significantly. Since liquids are nearly incompressible, and the rigid walls of the container prevent volume increase, this expansion rapidly generates enormous internal pressure. This immense pressure, resulting from the force exerted by the expanding liquid volume against the container walls, is known as hydrostatic pressure (pressure exerted by a fluid at rest) and is the direct cause of catastrophic failure (explosion) in an overfilled container. ### Why Other Options Are Incorrect: **A) discharge pressure from the recovery cylinder** This option is nonsensical. The "discharge pressure" refers to pressure leaving a component (like a compressor). The cylinder itself holds the pressure; it doesn't generate "discharge pressure" causing the dangerous internal pressure. **B) vapor pressure of the refrigerant at saturation temperature** Vapor pressure exists in the headspace above the liquid (the vapor zone) and is determined by the temperature of the liquid refrigerant. While vapor pressure increases with temperature, it is the *liquid* expansion (hydrostatic pressure) that causes the dangerous, destructive pressures. Vapor pressure alone, even at elevated temperatures, is orders of magnitude lower than the pressure generated by liquid expansion in a nearly full container. If there is sufficient vapor space, the pressure will remain safely within the limits defined by the vapor pressure curve. **D) discharge pressure of the recovery compressor** The recovery compressor's discharge pressure is relevant only during the filling process. Once the filling stops and the compressor is disconnected, the pressure inside the container is independent of the compressor. The dangerous pressure spike occurs later when the overfilled liquid heats up and expands.