Specially-charged, high-pressure, disposable,
compressed air cylinders were fired under water
in a protective steel chamber in order to obtain
flow curves and volumes as well as to test the
integrity of the actuating mechanism. High-
speed motion picture photography was used to
record any leakage or any failure of the assem-
bly. These types of cylinders are being evaluated
for use in purging and ventilating the hoods in
order to extend their useful duration.

Human Testing:

The feasibility of utilizing rebreathing tech-
niques, for short durations, was demonstrated by
use of an LB-1 infra-red CO, analyzer and by
continuously monitoring carbon dioxide accumu-
lation of subjects wearing various size plastic
hoods during rest and maximal work. The infra-
red protective capability of the clear and metal-
ized hood was evaluated by exposing human
subjects wearing the hoods to infra-red radiation
and measuring skin and interior and exterior
hood temperatures. These tests were carried out
with the subject’s protected head exposed to
radiation from four 250-watt industrial infra-
red lamps located at various distances from the

Fraure 2.—Subject wearing the clear, polyimide, smoke
hood is exposed to a natural gas flame.

Fravure 8.—Subject wearing the coated, silver, metalized
smoke hood emerges from a smoke-filled fuselage
into a gas-fed flame directed at his face.

face. Voltage to the lamps was controlled by a
variac and monitored by watt meters to assure
operation at the lamp rating.

Thirty-six gauge copper constantan type ther-
mocouples with an ice bath reference junction
were taped to the forehead, cheek, interior and
exterior of the hood. Skin and hood tempera-
tures were recorded on a Leeds and Northrop
Speedimax W Recorder calibrated to a range of
80 to 280°F. A thermocouple stepping relay
allowed recording of each of the four tempera-
ture positions at 7.5-second intervals.

Subjective evaluations of the hood have been
made by human subjects inserting their hood-
protected heads into natural gas flames as shown
in Figure 2. In addition, several tests have been
carried out in an obsolete Constellation aircraft
fuselage of 3,000 cubic feet volume in which
168,000-cubic-foot volume irritant smoke gre-
nades were fired. The subject donned the hood
after the grenade was fired and remained in this
environment for two to three minutes, then lo-
cated the exit and emerged to the exterior





Optical transmission as measured by the Beck-
nan spectrophotometer is not representative of
he human visibility capabilities of the hoods,
vut is, however, useful for comparison of metaliz-
ng systems. Thermal transmission measure-
aents indicated that the coated silver film had
ignificant superiority to the other coatings in
1eat reflectivity. After ten minutes exposure of
, silver metalizing system, the thermal differen-
ial measurements indicated a 92°F temperature
Ag of an inch from the inside or non-coated side
vith a 295°F temperature measured at a similar
listance from the exterior or coated side.

Disposable gas cylinders 414 x 11% inches were
tharged to 2000 psi with compressed air. Test
iring of these cylinders through very small fixed
wifices produced a very high initial flow curve
‘ollowed by a reduced flow as the pressure was
‘educed. This type of curve is desirable since
he initial high flow would tend to purge the

165
160
155
150

145

ee

140

°F

135

130

125

120

TEMPERATURE

Ws
OUTSIDE HOOD
110
105

100

00

00

95

000

hood and the subsequent lower flow provide sup-
plementary ventilation. In these initial tests,
the approximate nine liters total volume of the
cylinder was released in one minute. Attempts
are being made to increase both the volume and
flow duration of a hood ventilating system, and
at the same time minimize size and weight.

Human Testing:

Preliminary monitoring of the CO accumula-
tion indicated an accumulation and plateau of
6-8% COs after eight minutes of rebreathing at
rest. The shape of the curve indicated that the
seal around the neck began to develop significant
leakage in 4-6 minutes in response to the elevated
tidal and minute volumes of hyperventilation.
This was reduced to 24% to 3 minutes by maximal
work on a bicycle ergometer. The 2 mil. polyi-
mide film has sufficient rigidity so that it does
not exhibit a tendency to be drawn up against

TEMPERATURE °F

00

FOREHEAD TEMPERATURE °F

90 4

TIME

or

Ficure 5.—Hood and skin temperatures of subjects wearing

infra-red sources positioned twenty-two inches from the front surface of the hood. N

5

5 6

IN| MINUTES

the silver metalized polyimide hood and exposed to four
=i.



through a sheet of flame directed at his head and
face, as shown in Figure 8. In order to assure
mobility, these ‘subjects were not instrumented.
Tests were conducted to determine the reduction
of visibility induced by wearing the coated and
uncoated hoods under low level emergency light-
ing. Six random numbers of varying contrast
with their backgrounds were viewed by subjects
at the current interior emergency lighting stand-
ard level of .05 foot candles. The numbers were
chosen with contrast ratios such that some num-
bers were not perceived and/or were barely per-
ceived by the unobstructed eye at the .05 foot
candle levels of illumination. The clear, amber-
colored, polyimide hood was donned and the
illumination increased to a point where the sub-
ject perceived the same group of numbers as
observed at the .05 foot candles illumination
level without the hood. This was repeated with
the metallic coated hood. Between each test

subjects were re-adapted to illumination levels
approximating standard cabin lighting levels.
All measurements and light settings were made
using a Photo Research Spectra Milli-Candela
Photometer.

II. Results.
Material:

Emissivity values for the twenty-one metalized
samples of polyimide film were as follows:
coated gold—0.020-0.033; coated aluminum—
0.033-0.120; coated silver—0.008-0.025. The
thinner thicknesses of metal have the higher
emissivity values. The infra-red reflectance of
non-metalized polyimide film is approximately
25%. In these experiments with metalized polyi-
mide films, the IR reflectances were as follows:
coated gold—82.4 to 90.4%; coated aluminum—
76.2 to 90.2% and 90.3 to 90.9% for coated silver.

1657
teoF
155
isob .
.
. .
t4asb . . . ee °
. . : ° .
14ob ° ° . °3 e
+ ° 3 e ote
e oe e
135 3° ee ee 2.
w e . 3 r
© 3 : 3 so 8 fe : :
L Hy
& es es 2te ef °
ir ° . * 8 °
wast 3
= °
# vob 3 OUTSIDE HOOD TEMPERATURE °F
° °
TS g 8 88 e28 e2e 25 22
og ac 2° 8 g°8 808 858 ace fs
trok 8 ° ° °
° ° °
105+ 8
oe FOREHEAD TEMPERATURE °F
tooF 3
asp ge
sol L 4 L n it 4 i 4 1 4 1 nm 1 1 1 4 1 nm it 1 5
° 1 2 3 4 8 6 7 8 ry 10
TIME IN MINUTES

Ficure 4.—Hood and skin temperatures of subjects wearing the clear, polyimide hood and exposed to four infra-red
sources positioned twenty-two inches from the front surface of the hood. N = 12.

4


V. Discussion.

Phillips and Cope made a study of 1,140 con-
ecutive burn case hospital admissions with 106
‘atal cases and were surprised to find that shock
ecounted for only 20% of the deaths. Respira-
ory tract damage, with or without superimposed
espiratory tract. infection, was responsible for
early half of the burn fatalities. Where facial
yurns were incurred, 78% developed respiratory
lifficulties due to inhalation of flame. According
o Connell?, if the lower respiratory tree is
yurned; ie., trachea, main bronchi, and secondary
yronchi, death is almost inevitable.

The hoods do not provide protection from
yurns to the body. Clothing, however, provides
some degree of protection to high radiant tem-
oeratures for a few minutes depending upon the
sharacteristics of the weave and orientation of
she fibers1 As the temperature increases, there
s, however, danger of ignition. Survivors of
he Salt Lake City accident related that they
sulled suit coats, top coats and even shirts up
over their heads to provide protection from high
cadiant heat levels. One survivor, using this
nethod but standing with his back to the fire
focus and awaiting his chance to evacuate, re-
seived burns to one ear which protruded from
under his coat. Exclusive of burns to the head
and neck, male survivors of this accident most
frequently received severe burns to the hands
and area between the trouser cuff and shoes.
These are areas to which clothing provides little
or no protection from the effects of exposure to
radiant, convective and conductive heat.

Although full-body protection of passengers
has been considered, it does not appear to be
practical since the time required for donning

such a protective garment would probably delay
evacuation to such an’ extent as to be more detri-
mental than no protection whatsoever. In addi-
tion, the added complexity, passenger training
requirements and storage make this proposal even
less plausible.

The very light and compact polyimide hood
may prove to have potential usage for short
duration emergency protection in home, forestry
and industrial fires. However, additional test-
ing and design refinements should be carried
out with regard to. each specified proposed
application.

Prior to any specification for operational use
in aircraft, further studies are necessary. The
FAA is actively pursuing these avenues.

Vv. Summary.

1, Development of a polyimide smoke hood
designed to provide short duration protection
from the effects of inhalation of smoke, toxic
gases and flame is described. Additional protec-
tion is afforded the eyes from the temporary
blinding effect of irritant smoke.

2. The hood provides a barrier to direct flame
contact with the exposed face and head.

3. A. system for metalizing polyimide film
with a thin transparent layer of metal capable
of up to 90% infra-red reflectance was developed.

4, Duration of the usefulness of the hood may
be extended by a self-contained supply of un-
contaminated breathing air in order to purge
and provide supplementary ventilation of the
hood.

5. Prior to any specification for operational
use in aircraft, further studies are necessary.
The FAA is actively pursuing these avenues.

REFERENCES

1. Buertyer, K. Effects of Ewtreme Heat on Man,
JAMA 144782; 1950.

2, Connett, J. F. Research in Burns, Proceedings of
the First International Congress on Research in
Burns, Bethesda, Maryland, Sept. 19, 1960.

3. Herne, D, ALPA Cleveland Fire Test Results, Pre-
sented at the Thirteenth ALPA Air Safety Forum,
Oct. 4, 1966.

4. Marcy, J. F. A Study of Air Transport Passenger
Cabin Fires and Materials, Federal Aviation Agency
Report No. FAA ADS~44, Dec. 1965.

5. PHILLIPS, A, W. and, 0. Core, Research in Burns,
Proceedings of the First International Congress on
Research in Burns, Bethesda, Maryland, Sept. 1960.

6. Rorve, R. A. A Study of United States Air Carrier
Accidents Involving Fire 1955-1964, Civil Aeronautics
Board, Bureau of Safety Report No. BOSP-7-6-3.



AM 67-4

A PROTECTIVE PASSENGER SMOKE HOOD

Ernest B. McFadden, M.S.
Civil Aeromedical Institute

H. I. Reynolds, B.Ch.
G. T. Schjeldahl Company

and

Gorden E. Funkhouser, B.A.
Civil Aeromedical Institute

Approved by Released by
°
tle (USdge€ uo
J. Roserr Diz, M.D. P. V. Sixcer, M.D.
Cuter, Crvin AEROMEDICAL Feperan Arr Surcron
InsTITUTE
April 1967

FEDERAL AVIATION ADMINISTRATION
Office of Aviation Medicine



the respiratory passages and occlude breathing.
However, at the same time, it is flexible enough
to be responsive to changes in volume imposed
by inspiration and expiration.

Subjects wearing the clear, uncoated, amber-
colored, polyimide hoods and the coated silver
polyimide hood were exposed to eight minutes
of infra-red radiation with the filament of the
infra-red lamps located 22 inches from the front
surface of the hood. Forehead skin temperatures
and exterior hood temperatures are shown in
Figures 4 and 5. Using the clear hood, skin
temperatures of 115-117°F approached the limits
of voluntary tolerance. Skin temperatures of
subjects wearing the coated silver hood and ex-
posed to the same heat flux as the clear hood,

the front surface of the hood. Although exterio
surface temperatures occasionally exceeded re
corder calibration temperatures, the forehea:
skin temperature averaged approximately 106°F
Figure 6. Infra-red sources providing highe
levels of heat flux will be required to exten
these evaluations of tolerance.

Reduction in visibility induced by the clea
and metalized hoods at low levels of illuminati
is shown in Table 1,

Taste 1, Increase in illumination required to make se
lected targets equivalent in conspicuity while wear
ing the clear and metalized hoods as when viewer
by the unobscured eye at .05 foot candles of illumi
nation. N=it

FOOT CANDLES OF ILLUMINATION

exhibited maximum skin temperature of 100°F. Silver
The heat sources were moved to a point where Unobseured Amber Clear — Metalized
the filaments of the lamps were 6.5 inches from Bye Hood Hood
the front surface of the hood. This places the RANGE 0.05-0.05 063-100 60-4.30
lamp lens within one or two inches of contacting © MEAN 0.05 076 2.02
2807 3 3 3 3 3, ; $ 3 $
e e. oe
. .
L .
270 . . . . - 3s °
° e . .
260 /- e ° °
. .
. . eof ke . .
250 . . ° e? . ° ° .
. . . e ° . . ° e
oe e ° e
240 . ; . . 3
. .
& 230F s . °
° .
. .
Ww
Ww 220F
> \
& 210f OUTSIDE HOOD TEMPERATURE °F \
w .
a 200 | °
=
w
F oush
of
8
g ° 8 ° 8 8
L ° 8 8 8 goo 80 g 80
108 ae gis 25 88s Eek Bee bos a
wor ,, 8°°
83
95 L FOREHEAD TEMPERATURE °F
go 2 1. 1 4 Lo 4 1 mn 1 4 4 in rT 4 1 1 1 1 i 4 J
t 2 3 4 5 6 7 8 9 10

TIME IN MINUTES

Hieure 6.—Hood and skin temperatures of subjects wearing the same hood as shown in Figure 5 but with the infra-
red sources positioned 6.5 inches from the front surface of the hood. N = 11.

6


of which were equipped with modern interiors,
indicate that smoke density approaches saturation
in two to two-and-one-half minutes.? Tempera-
ture rise approaching intolerable levels (480°F)
occurred in these experiments at the fifth and
sixth minutes followed characteristically by a
flash fire with temperatures soaring to in excess
of 1600°F in one or two minutes as shown in
Figure 1. Smoke density and temperature meas-
urements in other tests indicate stratification
and localization, with flash fires reported to
travel through the fuselage at a rate of 68 feet
per minute.*

Current regulations require the airlines to
demonstrate that all passengers can be evacuated
in two minutes using one-half of the aircraft
exits. In the Salt Lake City accident, fire broke
out almost instantly after impact. Evacuation,
however, could not be initiated until the aircraft
came to rest, following a skid of some 2900 feet
which consumed some forty seconds to one min-
ute of the required evacuation time. Thus, the
two-minute evacuation time was cut nearly in
half. It is interesting to note that forty-three
(48), or one-half of the eighty-five (85) pas-
sengers aboard, failed to evacuate the aircraft
and became fatalities. If passengers in this type
of accident could have been protected from the
immobilizing and incapacitating effects of in-
halation of smoke, toxic gases, and flame, for
only one to two additional minutes of evacuation
time prior to the development of intolerable
temperatures, it is probable that a very signifi-
cant increase in survival could have been attained.

II. Methods.

A number of approaches to providing pas-
sengers respiratory protection was considered.
In this relation, the following primary and sec-
ondary design criteria were formulated.
Primary Design Criteria:

1. Simplicity in design and operation.

2. Omnidirectional visibility and donning.

3. Provide protection from smoke inhalation
for a limited duration (214 to 8 minutes).

4. Device should not melt or burst into flame
when worn on face or head.

5. Light-weight and compact in size.

Secondary Design Criteria:

1. Prevent inhalation of flames and respiratory
damage.

2. Protect the face and hair from direct con-
tact with flames.

3. Esthetic considerations—prevention of dis-
figuring facial burns.

4, Extend passenger escape time by maintain-
ing passenger mobility and continuation of evac-
uation.

5. Provide protection from convective and
radiant heat.

Material Testing:

A bag or hood type of device was constructed
of Kapton, a relatively new du Pont high téem-
perature polyimide film. Normal volume of the
hood was calculated to approximate 18.5 liters
exclusive of the volume occupied by the wearer’s
head. Kapton was selected due to its non-melting
character when exposed to extreme heat and be-
cause it is transparent and non-flammable. Kap-
ton, reportedly, does not begin to char until
temperatures exceed 1472°F. Other desirable
features of polyimide film for this application
include high tensile strength and folding endur-
ance, low shrinkage, insolubility in organic sol-
vents and inertness to fungi.

Since polyimide film has no melting point, ex-
perimental hoods cannot be fabricated by em-
ploying conventional heat-sealing techniques.
Experimental transparent hoods were fabricated
under contract by the G. T. Schjeldahl Company,
utilizing special techniques and high temperature
adhesives. A second group of experimental
hoods was fabricated by the same company em-
ploying a reflective but transparent metalizing
coating. Twenty-one samples of polyimide film
were successively coated with varying thicknesses
of gold, silver and aluminum, with and without
a protective coating over the metal. These sam-
ples were evaluated for infra-red reflectance and
emissivity plus heat and optical transmission.
Infra-red emissivity was measured by a Lion
Emissometer and infra-red reflectance by a
Perkin Elmer Spectrophotometer at wave lengths
from three to fifteen microns. Optical transmis-
sion was measured on a Beckman DKZA Spec-
trophotometer over the wave length range from
3500 to 7000 Angstroms. Thermal transmission
was measured by locating thermocouples equi-
distant (approximately %¢’’) from both sides
and measuring air temperatures using a common
infra-red lamp as the emitting heat source.


A PROTECTIVE PASSENGER SMOKE HOOD

Ernest B. McFadden, M.S.,
Civil Aeromedical Institute

H. I. Reynolds, B.Ch., G. T. Schjeldahl Company

and

Gorden E. Funkhouser, B.A.,
Civil Aeromedical Institute

I. Introduction.

Investigation of recent jet transport aircraft
accidents has indicated that inhalation of smoke
is a significant factor in the incapacitation of
passengers and their subsequent failure to evacu-
ate the aircraft prior to its consumption by fire.
Unfortunately, the immobilization and collapse
of even one strategically-located passenger or

crew member can have a very deleterious effect
upon passenger evacuation flow. A recent study
of United States air carrier accidents involving
fire concludes that fire deaths and injuries can
be reduced by aircraft crashworthiness design
evacuation provisions and procedures, plus air-
port firefighting and rescue provisions.© Recent

burn tests of obsolete instrumented aircraft, some

Smoke = Heat Smoke Heat
WOO 20 76" FROM CEILING
fat it
9oF Gist M
et = \ *
z 1 * 20" FROM
Z sot Giet i* CEILING
9° «
« = 1
we7of @l4ar ! REAR CABIN
u ! (BOTTOM)
| o !
6oF wi2t-
3 2 '
& 50- Sior y! MAIN CABIN
a w 1 (HEAD HIGH)
2 if
40h w BE
Esl ni |
<a 30+ @ 6 1 veces, CENTER CABIN
bt w weet 8" (SEAT)
x [4 h
© 20 a 4
5 z 1
2 !
toh = 2 1
ol ° 1 nl 1 Nn 4 n Nn 1 n 1 n n 1
o 1 2 3 4 & 6 7 8 9 10 HW 12 13 14

TIME IN MINUTES

Ficure 1.—Smoke and temperature data from Test Number 1 of the ALPA aircraft fire tests replotted on the same
time base in order to demonstrate the sequential occurrence of smoke and heat,

1



ACKNOWLEDGEMENTS

The authors wish gratefully to acknowledge the technical assistance of
James M. Simpson and John G. Blethrow. In addition, the authors wish
to recognize the cooperation of the subjects who endured considerable thermal
discomfort in order to contribute to the evaluation of the protective capability
of this device.

Qualified requestors may obtain Aviation Medical Reports from Defense Documentation
Center, The general public may purchase from Clearinghouse for Federal Scientific and
‘Technical Information, U.S. Dept. of Commerce, Springfield, Va. 22151