EDS APPLICATION NOTES
for various emergency oxygen back-up bypassing methods
The most common emergency bypassing method,
particularly for the EDS unit, is with the standard
issue F-2 oxygen mask kit. The pilot simply
unplugs the 4 mm. service line from the equipment
to be bypassed and mates it to the union on the F-2
mask kit. The flow indicator shows positive
oxygen flow for the duration of the cylinder's
capacity. The on/off valve on the cylinder then
controls the flow of oxygen.
The second most common method uses a self-
sealing "Y" with the F-2 mask where the pilot
would simply connect the 4 mm. inlet tube of the F-
2 to the "Y" for emergency service. This provides
the best and easiest to use back-up system for single
pilot applications. In addition, an option for adding
a delivery device for a future passenger is provided.
The third most common emergency bypassing
method is with the A-4 flowmeter/regulator control
unit that couples the outlets of the EDS unit and the
A-4 unit together into one standard cannula. This
allows the pilot to simply throw an on/off switch to
bypass the EDS unit, then having the ability to
adjust the flowmeter for the altitude to economize
on oxygen usage.
Because many pilots fly with passengers only part of
the time, the A-3 flowmeter/regulator and an
Oxymizer® cannula can be used for the passenger
instead of a second EDS unit. This of course will
use more oxygen than each using an EDS, but will
prove acceptable as it is less expensive and can be
up-graded to an EDS in the future.
This figure (below) shows the most popular back-up
bypass arrangement for the dual EDS systems. The
second set of "Y" split kit connecting the EDS units
and the F-2 mask kits are the self-sealing type. The
auxiliary opening will stay sealed until the 4 mm.
inlet tubing of the F-2 mask kit is plugged in for
emergency service.
Oxymizer is a trade mark of Chad Theruputics, inc.
The EDS has proven to be a very reliable oxygen delivery
device used by many in various types of aviation and has
no means inside itself to provide a by pass of oxygen in
the event of a total failure. Therefore, here are a few
oxygen bypassing methods implemented for that
comforting peace of mind.
