Cirrus DESIGN SR22 Pilot Operating Handbook page 326

Section 9 Cirrus Design
Supplements SR22 / SR22T
• The empennage proportioning unit distributes fluid to the LH
and RH horizontal panels.
In addition to distributing fluid to the porous panels and propeller
slinger ring, the proportioning units provide an additional, distinct
pressure drop to the supply lines such that a specific flow rate is
provided to each protected surface. Small, flap-type check valves
positioned on the outlet of each proportioning unit port prevent the
back-flow of fluid from the associated panel.
Porous Panels
The proportioned fluid enters the leading edge panels through the inlet
fitting(s) on the inboard end of the wing panels, and outboard end of
the horizontal panels. The outer surface of the panels is perforated
with very small openings to distribute the deicing fluid along their
entire length. The panels contain a porous membrane whose pores
are nearly 100 times smaller than the openings of the outer surface.
The leading edge panel serves as a reservoir as fluid entering the
panel fills the cavity behind the porous membrane then overcomes this
resistance to be distributed by the openings in the external surface.
The inlet fitting of the Inboard wing porous panel also supplies fluid to
the porous stall strip through an additional capillary tube which further
proportions the fluid to provide a specific flow rate to the stall strip.
Each panel incorporates a vent opposite the inlet which provides a
relatively large opening to release air from within the panel. A check
valve prevents air from entering the panel through the vent which
slows the "leak-down" of the panel during periods of inactivity.
Propeller Slinger Ring
Deicing fluid protects the propeller by a slinger ring mounted to the
spinner backing plate where the fluid is distributed by centrifugal
action onto grooved rubber boots fitted to the root end of the propeller
blades.
System Control
System operation is controlled by two switches located on the bolster
panel. The first switch controls system operation through ON and OFF
positions, the second switch controls the system mode (flow rate)
through NORMAL and HIGH positions.
16 of 20 P/N 13772-115
Revision 10: 09-20-12