A glycol proportioning station that provides a deicing mixture of glycol
and water to tank trucks that in turn spray the deicing mixture onto
aircraft. The invention includes a remote control that is positioned where
the truck is loaded and which runs in parallel with the controls on the
main unit of the system. The proportioning system operates with an economy
of parts by employing constant flow rates of both water and glycol. The
desired percentage of glycol in the effluent is obtained by initially
setting the position of one or more modulating valves provided on each of
separate water and glycol lines and then employing a refractometer
feedback loop to modulate the flow in one or both of the input lines. A
static mixer positioned along the effluent line upstream of the in-line
refractometer provides a uniform glycol-water mixture. The system provides
other novel features such as a "last fill" option that prevents the system
from freezing when it is not being used.
