The metering device typically an orifice (small hole) is used to restrict the
flow of the liquid from the condenser coil. As the liquid passes through the
orifice it loses pressure and becomes a much cooler liquid. Part of the liquid
flashes into a gas as it passes through the orifice and therefore there is a
gas/liquid (20/80) leaving the orifice. This is the liquid that enters the
evaporator coil.