Charge Factor

WARNING: This page is about a different car, the 2016 Volkswagen Beetle, 2015 Volkswagen Beetle, 2014 Volkswagen Beetle, and 2013 Volkswagen Beetle. However, it is still accessible from the selected car via links, so may be relevant.

A vessel must have space for vapor as well as liquid. As the temperature rises, the liquid expands. The space filled with vapor decreases. At a certain point, there will only be liquid in the vessel. Beyond this, even a slight increase in temperature causes high pressure to build up in the vessel as the liquid tries to continue expanding even though there is not enough space for it. The forces that result are strong enough to rupture the vessel. To prevent a vessel from being overfilled, the regulations regarding compresses gasses specify how many kilograms of refrigerant that may be added to a vessel per liter of interior volume. The product of multiplying this charge factor by the internal volume of the vessel is the permissible capacity. The figure for refrigerant used in vehicles is 1.15 kg/liter.