2
O Control
The LI-6400XT controls chamber humidity
by automatically varying the flow rate to
null-balance at the chamber humidity level you
specify in software; the input flow rate can also
be held constant. Flow rate is controlled by
pump speed in the standard system. With the
6400-01 CO
Injector System, pump speed
is constant and flow rate to the chamber is
controlled by redirecting excess flow. This
“shunt regulation” allows flow to be controlled
smoothly and quickly across a broad range.
2
Whether the controller in the 6400-01 is used
or not, air supplied to the chamber may be dry
or moist. Supplying the chamber with moist air
allows higher flow rates to be used to balance
low transpiration rates, which provides more
stable control and more accurate measurements.
Inaccuracies and time delays due to water sorption
on the air lines between
the console and
the
sensor head are
eliminated by
measuring the
reference
and sample water vapor
concentrations in the sensor head