even in copious quantities, is not an effective method of
preventing the breathing hose from sticking shut. It is an
effective irritant when inhaled, however.

One problem that resurfaced in phase 2 was the in-
cidence of broken nose clip clamps. This was no surprise,
as the apparatus procured for the study were collected
prior to the recall of the OXY-SR 60B SCSR’s.

Two deployed apparatus had inhalation check valves
that resonated during inhalation, causing higher inhala-
tion pressures, The same phenomenon occurred on base-
line units, This occurred only at one particular inhalation
flow rate drawn by the BMS. The phenomenon was re-
producible with human subjects but occurred only at that
same flow rate. It is unlikely that this phenomenon would
adversely affect an emergency escape.

The Wilcoxon rank-sum test (table 7) for average in-
haled O, indicates a lower mean value for the new units
than for deployed units. As can be seen from the O,
graph (fig. 2), however, the average inhaled O, values are
all close. In any case, higher O, concentration in deployed
units is not worrisome if the differences are, indeed, real.

Fifteen deployed units were successfully tested in
phase 2.

Tn phase 3, another unit with a broken nose clip clamp
was found, indicating that all users have not responded to
the manufacturer’s recall. Three deployed and one new
apparatus had inhalation check valves that resonated dur-
ing inhalation as indicated on the graphs as the greater-
than-normal inhalation pressures. As before, these pres-
sures would be only intermittent on human subjects and
would present no problem to the user.

Also, in phase 3, more complaints were received about
crimped breathing hoses. After opening 150 Draeger
SCSR’s collected from MSHA inspectors, it was discovered
that the crimp problem was more widespread and that
some crimps were difficult to undo. As a result, Draeger
retrofitted all of its apparatus with new hoses in 1991.

As can be seen in the inhaled CO, chart (fig. 7), one
deployed apparatus had much higher levels of CO, than
the others. In an effort to explain this, the data of other
apparatus tested on the BMS that day were reviewed and
it was found that the apparatus had normal CO, values, so
it is unlikely that the BMS put too much CO, into the
circuit, The apparatus was stored on a mantrip, as were
many others that had normal levels of CO,. It may be that
a manufacturing error resulted in the apparatus containing
less chemical than intended. The average inhaled CO,
level exceeded 4 pet after 66 min. This is high for the
Draeger OXY-SR 60B but physiologically tolerable and
no higher than the average of the CSE AU-9A1. In the
future, apparatus with such abnormal characteristics will
be disassembled in an attempt to explain their behavior.

15

This apparatus also had high inhalation pressures due to
‘Twenty-one deployed units were successfully tested in
phase 3.

MSA

In phase 1, it was found that many human subjects
cough during the first several breaths from MSA SCSR’s.
Although the exact cause is not certain, there are several
possibilities:

1. Talcum powder in the breathing circuit, used to keep
the rubber parts from sticking together.

2. Potassium superoxide (KO,) dust that was not fully
vacuumed out of the breathing circuit at the time of
manufacture.

3. KO, dust that escaped the filters of the chemical
bed resulting from shock and vibration sustained during
normal use.

While one case can be attributed to cause 3, most cases
were attributed to causes 1 and 2 if there was no damage
to the filters or beds. In any case, MSA has applied warn-
ing stickers to its apparatus advising that, should cough-
ing occur, the apparatus is not defective and should not
be removed.

Several early apparatus produced for the Bureau and
MSHA, and used by MSHA inspectors, were found to
have internal component frames that were dislocated
from their shock mounts and were in danger of falling out
of the lower case halves, This would have made the units
difficult to use. The condition was caused by one or more
severe drops; however, no damage to the outer case was
visible. This problem was resolved in commercially avail-
able models.

Fourteen deployed units were successfully tested in
phase 1.

In phase 2, the only problem found with an MSA SCSR
was one unit with a chlorate candle that failed to fire,
necessitating a manual start. Inspection of the unit at
MSA revealed a missing spring in the firing mechanism,
This was a quality assurance problem and was reported to
NIOSH.

The Wilcoxon rank-sum test (table 7) on both inhala-
tion and exhalation pressures indicates lower mean values
for baseline (new) units than for deployed units. As can
be seen on the breathing pressures graph (fig. 3), the
differences are slight. Since the Wilcoxon rank-sum test
for breathing pressures in phase 3 (table 8) does not show
a significant difference between new and deployed units,
increasing resistance does not seem to be a trend.


BREATHING PRESSURE,

DRY-BULB TEMP, °C AV INHALED 0 2, pet INHALED CO 2, pet DURATION, min

mm H, 0

120

110

100

90

80

70

7
6
5

45

40

35

30

25

BTM50g [Go Fogo g 0M

810 12 14 16 18
INDIVIDUAL UNITS

20 22

Key
Deployed unit
© New unit
4 Treadmill
key

5 Average
= Minimum
© Average, new unit
© Minimum, new unit
4 Minimum, treadmill

KEY
5 Deployed u
© New unit
‘© Treadmill

KEY
5 Deployed unit
© Newunit
4 Treadmill

KEY

3 Exhalation
= Inhalation
© Exhalation, new unit
© Inhalation, new unit
‘4 Exhalation, treadmill
‘4 Inhalation, treadmill

Figure 5.—PASS units, phase 2


UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT

°C degree Celsius min minute

h hour mmH,0 millimeter of water (pressure)
kg kilogram m/s meter per second

L liter pet percent

L/min _ liter per minute



16

Eleven deployed units were successfully tested in
phase 2.

In phase 3, the apparatus tested on a human subject
was accidentally run at a workload 30 pct higher than de-
sired; the test was graphed but should not be compared
with the other tests. Eleven deployed units were success-
fully tested in phase 3.

OCENCO

In phase 1, an Ocenco SCSR used in an actual escape
in the Greenwich Collicries mine fire of 1984 was found
to have its check valves reversed. This was considered
to be a quality assurance problem and was resolved by
NIOSH, MSHA, and the manufacturer.

The major problems with the Ocenco SCSR are its
stiff demand valve and its strong outer case. The pressure
required to elicit 30 L/min of O, from some of the de-
mand valves can reach -200 mm H,O, compared with ap-
proximately -40 mm H,O for the CSE demand valve. At
high O, use rates (higher than the usual constant flow rate
of 1.8 L/min), the demand valve is needed. Unless aware
of the high activation pressure, the user is likely to think
that the apparatus is malfunctioning. When 12 Ocenco
SCSR’s were used in the Greenwich Collieries mine fire,
5 testimonies indicated that the users felt that they could
not get enough air. In response, the users removed the
mouthpiece or nose clip, breathed around the mouthpiece,
or slowed down. Training would remedy this problem to
some degree, but the best solution is to replace this
demand valve with one that is not as stiff.

The strength of the clear, outer case of the Ocenco
SCSR enables it to withstand shock better than its internal
components. During the Greenwich Collicries mine fire,
12 of 17 units used for escape evidenced internal damage
sufficiently severe that, if damage occurred before use (the
likely case), the apparatus should have been removed from
service. LiOH from the scrubber was found in the breath-
ing circuits of five of the damaged units, All damage to
these apparatus was evident, but apparently not recognized
by the miners, the mine operators, or the mine inspectors.
Improved training in inspection procedures is obviously
necessary.

Another problem is the tight-fitting case halves, which
are extremely difficult to open without proper training. It
is recommended that training include special mention of
the opening procedure.

Thirty-eight deployed units were successfully tested in
phase 1.

In phase 2, three of five Ocenco SCSR’s from the
Greenwich Collieries #2 Mine failed their inspection cri-
teria and were returned to the mine and traded for appa-
ratus that passed their inspection criteria. One apparatus
had a shifted bottle band. Another had a cracked case.

A third had a shifted bottle band and a piece of loose rub-
ber in the case. A fourth had a very scratched case but
passed its inspection criteria. This apparatus was found
to contain enough LiOH in its breathing bag and hose to
cause severe coughing. Some LiOH had even escaped the
breathing circuit and could be seen through the scratched
case upon close inspection. It is not believed, however,
that a user would have detected this even under laboratory
conditions and certainly not under routine mining condi-
tions. This type of problem—an apparatus that passes its
inspection criteria but is unusable—is of primary concern
in the long-term field evaluation. As a result, the manu-
facturer has added an inspection criterion that reads as
follows:

"Inspect the apparatus for indications of high force
impacts. If the view through the case is obstructed such
that a proper examination cannot be performed (c.g, scuff
marks, stickers, paint) the unit must be removed from
service."

Two of the Ocenco SCSR’s had O, flow rates below the
required minimum of 1.5 L/min. The measured rates
were 1.44 and 1.48 L/min; shortfalls of these amounts
would have minimal effect on use.

As the flow rate from a normal regulator diminishes
during a test, the demand valve is activated more often.
The more the demand valve is activated, the higher the in-
halation pressure becomes because of the nature of the
stiff demand valve. The variation in regulator performance
with diminishing O, flow over time is evidenced by the
wide range of values for inhalation pressures that can be
seen in the graphs. Also contributing to this wide range of
values is the variation in stiffness of the demand valves,

Twenty-nine deployed units were successfully tested in
phase 2.

In phase 3, an apparatus with a missing cylinder neck
clamp was found. This would not have compromised a
successful emergency escape.

On the phase 3 graph for CO, (fig. 9), there are two
apparatus with higher-than-average values. High CO, val-
ues can be attributed to natural variation in the efficiency
of the CO,-absorption chemical, environmental impact, or
incorrectly high CO, add-rate during testing. The appara-
tus were not close in serial number (60627 and 68218), but
were from the same mine and had the same deployment
history: first carried in and out of the mine daily for
28 months, and then stored underground for 10 months.
The other units from that mine had different deployment
histories. The apparatus were tested 5 days apart, with
other apparatus tested between, before, and after that all
behaved normally, which tends to diminish the possibility
of an incorrectly high CO, add-rate while testing. The
values of the other monitored parameters were normal.
The fact that both apparatus had the same deployment
history leads one to believe that the environment or their


18

mine escape purposes. No problems have arisen involving
subtle performance degradation due to the mining en-
vironment. Manufacturing defects or improper design
were found, such as the CSE butrsting regulators and
missing mouthpiece; the Draeger broken clamps and
crimped hoses; the MSA defective starter candle and
coughing problems; the Ocenco reversed check valves,
burning Kel-F valve seat, and scratched outer case hiding
internal damage; and the PASS missing check valve, incor-
rectly set regulator, unpredictable high CO, levels, and

still-mysterious low O, levels. All of the defects. were
detected immediately upon attempting to don the appa-
ratus except for those of the PASS SCSR, which is being
removed from service. The discovery of a defective ap-
paratus gives the user the opportunity to use another one,
since usually extra SCSR’s are stored. Even with this op-
tion, however, these problems evidence the need for con-
tinued monitoring, preferably by the Government, whose
independence is important.

INT.BU.OF MINES,PGH.,PA 29501


BREATHING PRESSURE,

AV INHALED 0, , pet INHALED CO, , pet DURATION, min

TEMP, °C

mm H,0

120

110

100

100

80
70

50
40
30

50

35

30

25

KEY
5 Deployed unit
© New unit
4 Treadmill

KEY
Average
Minimum
Average, new unit
Minimum, new unit
Minimum, treadmill

KEY

2 Deployed unit
New unit
Treadmill

po

KEY
Dry bulb
Wet bulb
Dry bulb, new unit
Wet bulb, new unit
Dry bulb, treadmit

peoma

KEY
Exhalation
Inhalation
Exhalation, new unit
Inhalation, new unit
Exhalation, treadmill
Inhalation, treadmill

16 20 24 28 32 36 40 44

INDIVIDUAL UNITS

Figure 9.—Ocenco units, phase 3


BREATHING PRESSURE,

AV INHALED O, , pet INHALED CO, , pot DURATION, min

DRY-BULB TEMP, °C

mm HO

120

110

100

80

70

60

vio sa

°
100
90
80
70
60
50
40
30
20

50

45

40

35

30

5

L

a 0 °
o ° °
o
o °
TM— rr
°
oo °
°
oo .
. .
ee
. =a
oo °
o
a °
°
°
oo ? ° °
o o ° °

25 %_ 900 go

5 6 7 8 9 10111213
INDIVIDUAL UNITS:

15 16

KEY

2 Deployed unit

© Newunit

a
.
°
°
a

o
°
a

°
a

>rpeona

KEY
Average
Minimum

Average, new unit
Minimum, new unit
Minimum, treadmill

KEY
Deployed unit
‘New unit
Treadmill

KEY
Deployed unit
New unit
Treadmill

KEY

Exhalation
Inhalation
Exhalation, new unit
Inhalation, new unit
Exhalation, treadmill
Inhalation, treadmill

Figui

1.—CSE units, phase 2


INTRODUCTION

On June 21, 1981, coal mine operators in the United
States were required to make available to each under-
ground coal miner a self-contained self-rescuer (SCSR).
The regulations (30 CFR 75.1714) require that each per-
son in an underground coal mine wear, carry, or have
immediate access to a device that provides respiratory
protection with an O, source for at least 1h, as rated by
the certifying agency, the National Institute for Occupa-
tional Safety and Health (NIOSH). To ensure the safety
of miners using these apparatus in an emergency, the
US. Bureau of Mines and the U.S. Mine Safety and
Health Administration (MSHA) are conducting a long-
term, in-mine evaluation of SCSR’s now deployed in

underground coal mines. In this study, MSHA’s respon-
sibility is to identify the participating mines and to procure
from those mines the SCSR’s to be tested. The Bureau
replaces the SCSR’s to be tested with new apparatus and
tests the SCSR’s in its laboratories. The objective of this
long-term program is to evaluate the in-mine, operational
durability of SCSR’s. Of utmost concern is the successful
performance of any SCSR that passes its manufacturer's
inspection criteria. The Bureau is interested only in appa-
ratus that pass their inspection criteria. Such apparatus
are relied upon to function successfully in an emergency.
Apparatus that fail inspection criteria are expected to be
removed from service.

EXPERIMENTAL PROCEDURE

This program involves testing approximately 100 SCSR’s
in each phase of the study. This report describes findings
over the first 8 years of deployment, in which more than
300 apparatus were tested in 3 phases. Testing was con-
ducted using a breathing and metabolic simulator (BMS)
and human subjects on a treadmill.

The SCSR’s tested were manufactured by CSE Corp.;
Draegerwerk AG; Mine Safety Appliances Co., Inc,
(MSA); Ocenco, Inc.; and Portable Air Supply Systems
Corp. (PASS) and were sampled according to market
share (table 1). The sampling was modified to ensure that
at least 10 SCSR’s from each manufacturer were sampled
for each phase of the program.

Table 1.—Self-contained self-rescuers received for evaluation

Estimated Quantity inspected

Apparatus market share, Phase Phase Phase
pet 1 2 3
CSE AU-9A1.......++ 20 26 7 24
Draeger OXY-SR 60B .. 21 21 7 23
MSA 60-min SCSR .... 4 15 12 12
Ocenco EBA 6.5 . . 54 440 38 47
PASS 700... t 10 21 i)
Total .. 6.250% . 100 116 = 105 106

Apparatus were not tested if they failed to pass in-
spection criteria or had a manufacturing defect or design
deficiency that prevented testing.

MSHA selected the participating mines with regard
to type of mining operation, seam height, and SCSR de-
ployment mode to obtain a representative cross section
of U.S. mines.

The researchers planned to conduct 90 pct of the tests
using the BMS and 10 pet using human subjects. During
phase 1 (1983-84) the old BMS was replaced with a newer
design. For a period, no BMS was available, so human-
subject testing was relied upon exclusively. Approximately
half the apparatus were tested on the BMS in phase 1 and
the remainder were tested on five human subjects, whose
weights are given in table 2, Phases 2 and 3 were conduct-
ed according to the target of 90 pct BMS tests and 10 pet
human-subject tests.

Table 2._Weights of human
subjects for treadmill
tests, phase 1
Subject Weight, kg

64
82
64
93
80

The human-subject test consisted of the treadmill equiv-
alent of the 1-h man test 4 from 30 CFR 11. The BMS
test consisted of the average metabolic work rate exhibited
by the S0th-percentile miner weighing 87 kg while per-
forming the 1-h man test 4. The metabolic workload (vol-
umes at standard pressure and temperature, dry (STPD))
is given in table 3. The breath waveform shape of the first
BMS was a sine wave.

In phase 2, during 1985 and 1986, two human subjects
were used in the treadmill tests. The subjects walked on


SELF-CONTAINED SELF-RESCUER FIELD EVALUATION:
RESULTS FROM 1982-90

By Nicholas Kyriazi' and John P. Shubilla?

ABSTRACT

A joint effort by the U.S. Bureau of Mines and the U.S. Mine Safety and Health Administration
(MSHA) was undertaken to determine how well self-contained self-rescuers (SCSR’s), deployed in
accordance with Federal regulations (30 CFR 75.1714), survived the underground environment with
regard to both impact damage and aging, This report presents findings regarding laboratory-tested
SCSR’s from 1982 through 1990, The SCSR’s were tested on human subjects and on a breathing and
metabolic simulator (BMS). These results indicate that most of the apparatus, if they pass their in-
spection criteria, perform as expected except for units with manufacturing defects or design deficiencies.
However, when the apparatus are carried in and out of the mine daily and stored at the working section,
they may suffer abuse. Physical signs of abuse, unless extremely obvious, are frequently not detected
by the miners or mine operators. This poses a potential danger to a user in an emergency. Recom-
mendations include improved training in inspection procedures.

‘Biomedical engineer.
ineering technician,
Pittsburgh Research Center, U.S. Bureau of Mines, Pittsburgh, PA.


14

In phase 2, regulators from several SCSR’s blew apart
when their cylinder valves were opened. One incident oc-
curred at an MSHA district office; two more regulator
bursts occurred in the Bureau laboratory where the tests
were conducted; another occurred at NIOSH. CSE’s re-
sponse to NIOSH was to recall and retrofit the SCSR’s
with a modified regulator.

The human-subject tests in phase 2 were terminated
arbitrarily shortly after 60 min for the benefit of the
human subjects. Those durations are not shown in the
graphs since the apparatus were not expended at termi-
nation as were the ones tested on the BMS.

One human subject experienced breathing pressures
that became so high that he was barely able to complete
the test. Afterward, the subject was exhausted and be-
came lightheaded. The apparatus was taken to CSE and
dismantled. No defect could be found in the apparatus,
but the recorded high pressures, which reached 210 mm
H,0 on exhalation and 280 mm H,0 on inhalation, cannot
be denied. High ventilation rates may have caused the
high pressures. The human subject is, perhaps, a CO, re-
actor, who responds to the inhalation of CO, with exces-
sively increased ventilation. Since the CSE AU-9A1 has
the highest values of inhaled CO, of any of the apparatus,
this would explain why he experienced no similar problem
with the others.

As in the first phase of this study, a few apparatus were
sent that should have been removed from service because
of obvious damage. Some rattled when handled. Usually,
this rattling indicated that the plastic regulator clamps
were broken.

One unit was missing a lead seal and had a paper seal
that had curled away from the case, revealing the remnants
of an old paper seal. When it was opened, the mouthpiece
was found to be missing. This unit was put into service in
June 1982, was checked by CSE in December 1982 as part
of a recall of all its SCSR’s, and was collected for this
study in November 1984. As a result of this finding, 10
more units were procured from the same mine and were
inspected. No further problems were discovered. In addi-
tion to the missing mouthpiece, this apparatus had a con-
stant O, flow rate of 1.47 L/min, which is less than the
required 15 L/min. The expiration date for the unit had
passed between the time it was collected and tested. This
is not sufficient reason to excuse the apparatus, but, in
any case, a low flow rate on the constant-flow regulator is
easily made up through increased use of the demand valve.
All of the other CSE SCSR’s had O, flow rates above the
required minimum. Eleven deployed units were success-
fully tested in phase 2.

In phase 3, two units that had been procured for the
study before the recall involving replacement of defective
regulators vented their O, bottles when the cylinder valves
were opened,

One apparatus that had legally expired 18 months be-
fore it was received was tested in phase 3 for informational
purposes only. This apparatus had large and small dents
in the outer case, and one of its paper seals was broken.
This apparatus had CO, levels higher than any other,
with average inhaled values exceeding 4 pct for the last
20 min beginning at 55 min. According to the manufac-
turer, if the CO, absorbent, lithium hydroxide (LiOH),
absorbs moisture, its efficiency is lessened. If that was the
case with this particular apparatus, removing an expired
unit from service can be seen as important. Twenty-two
deployed units were successfully tested in phase 3,

DRAEGER

Tn a study of Draeger SCSR’s carried by MSHA in-
spectors, two units had broken clamps around the flow-
splitting valve housing at the interface of the breathing bag
and breathing hose. During the simulated escape test in
which these were discovered, one unit’s breathing hose
separated from its breathing bag, rendering the unit un-
usable. The other unit held together. Draeger recalled its
apparatus to replace this clamp as well as the nose clip
clamp, which had also been found to experience some
breakage.

One other discovery was that a significant percentage
of the Draeger SCSR’s had breathing hoses that were
crimped where they were folded for packaging, Uncrimp-
ing the hose is usually simple but should be mentioned in
the training procedure. Draeger has added this instruction
to its manual.

Inspection of 13 units that had been subjected to ex-
plosive forces in the Clinchfield Coal Co.’s McClure #1
Mine disaster in 1983 showed that even apparatus with sig-
nificant damage performed normally and could have been
used for an escape.

There have been two cases in which Draeger SCSR’s
were sent in from various MSHA districts with reports that
they failed to function properly. Upon testing, the appa-
ratus were found to function normally, implying improper
use. Improved training procedures may prevent such oc-
currences. Twenty-one deployed units were successfully
tested in phase 1.

In phase 2, one apparatus from the McClure #1 Mine
had sufficient talcum powder in the breathing hose to
cause mild irritation and to make the test subject want to
spit. This raises concern that some users may choose to
abandon the apparatus. Another apparatus, from the
Ranger Fuel Corp.’s Beckley #2 Mine, had a severely
crimped breathing hose that could not be uncrimped. In
addition, talcum powder was visible below the crimp in
the hose. A frayed waist strap indicated that the apparatus
had been carried frequently. All other inspection criteria
were met. It seems that the presence of talcum powder,


RESULTS AND

Experience with each brand of apparatus is discussed
separately for all phases. The numerical results of phase 1
have been published previously‘ and will not be repeated
here. The major conclusion for phase 1 was that SCSR’s
that pass their inspection criteria can be expected to func-
tion successfully except for those that have quality control
problems. In phase 1, apparatus were sent for evaluation
that were obviously damaged and should have been remov-
ed from service. No performance degradation was experi-
enced that could be attributed to exposure to the mining
environment,

For phases 2 and 3, the parameters monitored were
averaged over the entire test duration and are presented
graphically (figs. 1-9) for each apparatus by parameter.
The values for deployed units tested on the BMS are
compared with the values for new units tested on the BMS
and with deployed units tested on human subjects on a
treadmill. Missing data points are indicative of equipment
malfunction or other anomaly that invalidated the data.

The Wilcoxon rank-sum test was performed for each
monitored parameter to determine whether or not the
deployed units behaved differently from new units. This
method tests the hypothesis that the two samples are from
populations with the same mean. The values from both
samples are ranked in ascending order of magnitude. If
the sum of the ranks of the smaller sample (T) (in this

‘Kyriazi, N., J. G. Kovac, J. Shubilla, W. Duerr, and J. Kravitz. Self-
Contained Seif-Rescuer Field Evaluation: First-Year Results of 5-Year
Study. BuMines RI 9081, 1986, 12 pp.

DISCUSSION

case, new units) falls within an acceptable range for the
given sample sizes, then there is not sufficient evidence at
the specified probability level to say that the means of the
two samples differ. The rank-sum test does not rely upon
the assumptions that either the baseline or deployed data
are normal distributions or that they have identical var-
jances, as does the t-test for two populations of inde-
pendent samples. One limitation of the Wilcoxon rank-
sum test is that it does not distinguish between large and
small differences in values. The results of the two-sided,
P = 0.05 Wilcoxon rank-sum tests are presented in tables
7 and 8, The probability of T, the rank sum of the base-
line units, falling outside the given range is 0.05 if the
populations have the same mean.

CSE

In phase 1, one SCSR was rejected because of damage
(no intact lead seal and rattling of internal components),
‘When it was opened, its components fell out. This unit
should have been removed from service. If there is inter-
nal damage to a CSE apparatus, it may rattle when shak-
en, or the O, bottle gauge may have shifted, making it
hard to read.

When a CSE SCSR is dropped on the lower case latch,
the case bottom is pushed in, which can puncture the
breathing bag. Although this can be easily seen, some-
times it is not recognized. Improved training in inspection
procedures could correct this situation.

Twenty-five deployed units were successfully tested in
phase 1.

Table 7.—Wilcoxon rank-sum test results, phase 2

AV AV Dry-bulb Inhalation Exhalation
Apparatus Duration inhaled CO, _inhaled O, temp pressure pressure
Range T Range T Range T Range 7 Range 71 Range T
15-41 25 14-38 3 18-41 20 (15-41 2 15-41 20 «1540 0-32
19-57, 28 (18-54 43 «1957 15 1957) «37: 19-57 54012-4544
10-35 18 933 7 933 "1 10-35 17 10-35 8 1035 8
16-65 32 04 94 16-68 4H 3004 70 30-04 62 3004 «64
13-50 23 1350 57 13-53 4 1353 6 1353 171350 —'19
T ‘Sum of the ranks of the smaller sample (new units).
Table 8.—Wilcoxon rank-sum test results, phase 3
Av Av ‘Wet-bulb Dry-bulb Inhalation Exhalation
Apparatus! Duration inhaled CO, —_inhaled O, temp temp pressure pressure
Range T Range 1 Range T Range 1 Range 1 ange T Range T
2472 620 «23-469 «41 14-5841 13-53 440145537) 24-72 4424-72. 49
2472 72 24-76 62 24-76 62 2369 26 1458 38 17-55 30 2476 a“
nee 1956 33) 2456 3422-53 4302456 2724-56 362456 2824-56 26
Ocenco 1560361560 «42S 15-60 «639145815 15-60 2515-60 25145839

T Sum of the ranks of the smaller sample (new

nite).
PASS not tested in phase 3,


RI} 9401 REPORT OF INVESTIGATIONS/1992,

Self-Contained Self-Rescuer Field Evaluation:
Results From 1982-90

By Nicholas Kyriazi and John P. Shubilla

UNITED STATES DEPARTMENT OF THE INTERIOR

BUREAU OF MINES


BREATHING PRESSURE,

INHALED co,, pet DURATION, min

AV INHALED 0, , pet

DRY-BULB TEMP, °C

mm H, 0

120

110

100

40

35

°
0 2 °
.
5
. °
.
o oo 2°
s =e wepoe
mm ee
o
nooo
°
2 °
5 o
a
o o e 6
5 ooo Fa go

4

5 6 7 8 9 101112
INDIVIDUAL UNITS

13

14°15

peoma

a
°
a

o
°
a

prpeoma

KEY

Deployed unit
New unit

Minimum, new unit
Minimum, treadmill

KEY

Deployed unit
New unit
Treadmill

KEY
Deployed unit
New unit
Treadmill

KEY

Exhalation
Inhalation
Exhalation, new unit
Inhalation, new unit
Exhalation, treadmill
Inhalation, treadmill

Figure 3.—MSA units, phase 2


110
s
& 100
Z KEY
Ss % J 2 Deployed unit
54 a © New unit
= 20 oo? oo ° Treadmill
2 So oe
70 o o °
o
60
s Kl
° EY
8 5 Average
a = Minimum
2 © Average, new unit
= © Minimum, new unit
Zz 4 Minimum, treadmill
90
z o og o@
o o oo
= eof %o 0 a oof,
6 70 ° q KEY
2 6 J 2 Deployed unit
© Newunit
3 50 & Treadmill
= 40
< 30
20
50 —
48 e a
3
° 2 2, 5 oy
y ° 2 a 5 .
Fo oe ° KEY
2. a © Deployed unit
a 30 © New unit
3 4 Treadmill
E 25
20 1
150 T
8 100 a
2 i a |
a ° J KEY
°
a re ce
° . ee inhalation
Z E +00 . © Exhalation, new unit
z= 150+ © Inhalation, new unit
s ‘4 Exhalation, treadmill
g -200F ‘& Inhalation, treadmill
250 roar
o 2 4 #6 6 10 12 14 16 18 20
INDIVIDUAL UNITS

Figure 2.—Draeger units, phase 2


the treadmill at whatever speed resulted in an O, con-
sumption rate of 1.35 L/min (STPD). Their weights and
speeds are listed in table 4. Keeping the O, consumption
tate constant for the different human subjects and the
same as that of the BMS made the data from each human
subject and the BMS more comparable. When different
human subjects perform the same activity (1-h man test 4
in phase 1), O, consumption rates vary with weight, physi-
cal condition, and genetic differences.

Table 3.—-BMS metabolic workload for phase 1

©, consumption rate . ~Umin.. 1.35
CO, production rate «U/min,, 1.30
Ventilation rate . . sU/min., 31.9
Tidal volume ~ Lperbreath., 1.21
Resplratory frequency breaths permin.. 26.5.
Peak respiratory flow rate .........46 L/min.. 100
BMS —_Breathing and metabolic simulator.

Table 4.~Weights and speeds of

human subjects for treadmill
tests, phase 2
Subject — Weight, kg Speed, m/s

64 18
82 16

The new BMS was used in phase 2, Although the met-
abolic workload and breath waveform shape (sine wave)
were the same as in the first phase, the difference in de-
sign between the two BMS’s makes the data between
them incomparable. See Bureau IC 910° for detailed de-
scriptions of the designs of the old manual Reimers BMS
and the new DEEC Inc. automated BMS.

In phase 3, during 1987 and 1988, the breath waveform
used in the BMS testing was more humanlike, with lower
peak flow rates than a sine wave generates for the same
ventilation rate, In addition, while the same O, consump-
tion rate was used, the other parameters of the metabolic
workload were somewhat different, more closely resem-
bling the human subjects (table 5), The human-subject
testing procedure was not changed from that used in
phase 2, The weights and speeds of the six human sub-
jects are listed in table 6.

In all phases of the study, the parameters monitored
were CO,, O,, temperature, and breathing pressures in

*Kyriazi, N. Development of an Automated Breathing and Metabolic
Simulator. BuMines IC 9110, 1986, 17 pp.

both the BMS and treadmill testing. In the BMS testing,
however, average inhaled levels of CO, and O, were meas-
ured as well as minimum levels of CO,, whereas only
minimum levels of CO, and maximum levels of O, were
measured in the treadmill testing, Average inhaled gas
levels reflect the overall quantity of gas inhaled, including
the effect of apparatus dead space, whereas minimum
values of CO,, for example, reflect only the best perform-
ance of the scrubber. The BMS measures average inhaled
values by summing electronically (new BMS) or mechani-
cally (old BMS) all of the inhaled CO, and O, from the
beginning to the end of each inhalation, as described in
RI 9110. Maximum inhaled dry-bulb gas temperature was
measured in phases 1 and 2, whereas end-of-inhalation,
dry- and wet-bulb gas temperatures were measured in
phase 3, In all phases, peak inhalation and exhalation
breathing pressures were measured.

Table 5.-BMS metabolic workload for phase 3

©, consumption rate L/min. 1.35

CO, production rate .Umin.. 1.10
Ventilation rate L/min.. 30.0
Tidal volume . Lperbreath.. 1.68
Respiratory frequency breaths permin.. 17.9
Peak respiratory flow rat
Inhalation »Umin.. 89
Exhalation «L/min... 1
BMS —_ Breathing and metabolic simulator,
Table 6.—Welghts and speeds of
human subjects for treadmill
tests, phase 3
Subject Weight, kg Speed, m/s
A. . 88 1.56
B 90 174
Cc 96 1,65
D 86 1,70
E 7 1,79
F 92 1.74

In phase 1, the termination criteria were a collapsed
breathing bag indicating an exhausted O, source, or aver-
age inhaled gas concentrations of 24 pet CO, or <15 pet
O,, In subsequent phases, the levels of gas concentrations
were dropped as termination criteria upon consideration
that the only positive signal a user would have in actual
use would be an empty breathing bag.


handling had some effect on the CO,-absorbent bed. It
is not known what type of environmental treatment
would reduce the efficiency of the LiOH bed. In any case,
the apparatus had durations of 99 and 104 min, by which
time the average inhaled CO, had reached approximately
4 pet. This would hardly have been noticed by a user, es-
pecially for the brief period of exposure.

In May 1990, a new unit experienced ignition of the
Kel-F plastic (homopolymer of chloro-trifluoroethylene)
valve seat in the O, cylinder valve when the valve was
opened. A strong smell of chlorine and/or fluorine ema-
nated from the breathing hose; this would have prevented
the apparatus from being used in an emergency. Whether
the ignition occurred because of hydrocarbon contamina-
tion in the valve or a Kel-F plastic shaving, industry
experience suggests the susceptibility of Kel-F plastic to
ignition in 100 pct O, atmospheres. Other manufacturers
have switched valve seat material from Kel-F plastic to
Vespel polyimide resin with no further reported problems.
NIOSH has been notified of the incident. Forty-five
deployed units were successfully tested in phase 3.

PASS

In phase 1, two of the PASS SCSR’s, for reasons still
unknown, underwent a decrease in O, concentration to be-
low 15 pet, requiring termination of the tests. When these
units were later refilled with O, at PASS’s facility, the O,
flow rates were found to be in compliance with specifica-
tion, Since other apparatus were successfully tested imme-
diately after their failures, malfunctioning measurement
equipment was ruled out. One possible explanation is that
the constant-flow regulators were initially clogged with
particulate matter that later freed itself. Since these in-
cidents could not be repeated nor the causes determined,
they were not pursued beyond reporting them to NIOSH.

One SCSR, during treadmill testing, permitted high
inhaled CO, concentrations during the first several
breaths. It was found that the inhalation check valve was
missing. This was considered to be a quality assurance
problem and has been handled by NIOSH. Six deployed
units were successfully tested in phase 1.

In phase 2, one unusual occurrence involved a PASS
SCSR with an extraordinarily long duration (114 min),

7

This is not to say that a user could have worn the unit that
long, since both average and minimum inhaled CO, had
reached 15 pet before that time. It is believed that the
constant-flow regulator was not releasing its required
3 L/min of O, over the first 60 min of use. Since only
135 L/min STPD was removed from the apparatus on
the simulator test, nothing unusual was noticed until the
apparatus performed longer than the usual time. After
60 min, even normal apparatus are permitted to have flow
rates less than 3 L/min, so this postulation could not
be positively determined.

Tn phase 2, all of the baseline (new) units had average
and minimum inhaled CO, levels higher
than those of the deployed units (fig. 5). The dry-bulb
temperatures for the baselines were also much lower than
those of the deployed units, indicating that the soda-lime
beds were less reactive, permitting more CO, to pass
through the beds unabsorbed and, thus, producing less
heat. There are several possible explanations for this
behavior. Since the baseline units were tested as a batch,
close in time to each other, approximately 9 months be-
fore the deployed units were tested, it is possible that too
much CO, was injected into the units. To test that theory,
more new units were tested in 1990. They had even higher
levels of CO,, It was noticed that the baseline units had
much higher serial numbers than the deployed units. The
deployed unit serial numbers ranged from 317 to 2689.
The baseline unit serial numbers ranged from 3110 to
3308. More units of lower serial number were tested and
both good and bad results regarding CO, breakthrough
were recorded. MSHA obtained two units from different
mines and one from storage at its facility. The two from
the mines did well but the one from storage had high CO,
levels, A direct correlation was found, with one discrep-
ancy, between CO, breakthrough time and canister weight.
No other correlation has been determined as of this
writing,

One unit was rejected because of a cylinder gauge that
was not visible. Nineteen deployed units were successfully
tested in phase 2.

No PASS SCSR’s were tested in phase 3 since few re-
main in use and the manufacturer has ceased operations.
The PASS SCSR is no longer considered approved by
MSHA and NIOSH.

CONCLUSIONS

A number of quality control problems were discovered
in the long-term field evaluation. These problems were
teported to NIOSH, MSHA, and the breathing apparatus
manufacturers. In each case, action has been taken to
solve the problems.

Certain SCSR’s collected during the study were dam-
aged by daily in-mine use and should have been removed

from service. The damage was generally apparent and
visible and should have been detected if the SCSR’s had
been properly inspected. Improved inspection training is
recommended.

The results of this study suggest that the large majority
of SCSR’s that pass their inspection criteria can be relied
upon to provide a safe level of life support capability for


CONTENTS

Abstract .....
Introduction
Experimental pri
Results and discussion .
CSE...
Draeger .
MSA ..
Ocenco .
PASS .
Conclusions

ILLUSTRATIONS

. CSE units, phase 2 ...
Draeger units, phase 2 .
MSA units, phase 2 ..
Ocenco units, phase 2 .
PASS units, phase 2. .
CSE units, phase 3 ..
Draeger units, phase 3 .
MSA units, phase 3 ..
Ocenco units, phase 3...

PENIAWEYNE

TABLES

. Self-contained self-rescuers received for evaluation .....
Weights of human subjects for treadmill tests, phase 1

BMS metabolic workload for phase 1.............
Weights and speeds of human subjects for treadmill tests, phase 2 .
BMS metabolic workload for phase 3 .............0eee eee
Weights and speeds of human subjects for treadmill tests, phase 3 .
Wilcoxon rank-sum test results, phase 2 .

Wilcoxon rank-sum test results, phase 3 . .

SPN AwAYNE

RRYLWWUNN


10

BREATHING PRESSURE,

3

3

100

80

INHALED CO,, pct DURATION, min

AV INHALED O,, pet
88

Bg? gpaog pe a F Sek 4,
eae
Pe8 oo ®onoooo og gD FOGg % 9%
Pee eee
o 2 4 6 8 10 12 14 16 18 20 22 24 26

L . . °
o
[5 a4 °
oo o a ° a
a o 7, a
o o °
a 3
r o °
o o o
e2 0 og g o °
a o 97555", oo yf
= 8 J
=e s8 8 . eee ele
Ce Seid Beir A 2
fo
o
b o Oo o o a °°
a a a
a 5 3 a
o ° °
a 0 a

INDIVIDUAL UNITS

peoaa

peoan

KEY
Deployed unit
New unit
Treadmill

KEY

Average
Minimum
Average, new unit
Minimum, new unit
Minimum, treadmill

KEY
Deployed unit
‘New unit
Treadmill

KEY

Dry bulb

Wet bulb

Dry bulb, new unit
Wet bulb, new unit
Dry bulb, treadmill

KEY
Exhalation
Inhalation
Exhalation, new unit
Inhalation, new unit
Exhalation, treadmill
Inhalation, treadr

Figure 6.—CSE units, phase 3


BREATHING PRESSURE,

120

110

100

DURATION, min

INHALED CO,, pct
eegxseesso-

&

AV INHALED Op , pet

83s

45

40

TEMP, °C

mm H, 0
8

5
° q
ooo °
. 4
o ® °
°
°
8
4. 1 1 t
0
ofa °
go") Got, one gy 2 ry
os . a 3 co
prepi ties
°
o 8 °
a7 o ° °
i) o o *
a
oo 5 g ee ©
o o e °
. a
o a
. .
. . . .
. . ee
=. ar
a
"as "50955559000
i i er
123 4 5 6 7 8 9 1011121314151617

INDIVIDUAL UNITS.

KEY

Deployed unit
© New unit
‘4 Treadmit!

peoaa

peoma o

preoma

KEY
‘Average

Minimum
‘Average, new unit
Minimum, new unit
Minimum, treadmit

KEY
Deployed unit
New unit
Treadmill

KEY

Dry bulb

‘Wet bulb

Dry bulb, new unit
Wet bulb, new unit
Dry bulb, treadmill

KEY

Exhalation
Inhalation
Exhalation, new unit
Inhalation, new unit
Exhalation, treadmill
Inhalation, treadmill

Figure 8.—MSA units, phase 3


Library of Congress Cataloging in Publication Data:

Kyriazi, Nicholas.
Self-contained self-rescuer field evaluation : results from 1982-90 / by Nicholas
Kyriazi and John P. Shubilla.

P. cm. — (Report of investigations / United States Department of the
Interior, Bureau of Mines; 9401)

Supt. of Docs. no.: 1 28.23:9401.
1. Self-contained self-rescuer (Mine rescue equipment)—Testing. I. Shubilla,

John P. Il. Title. Il. Series: Report of investigations (United States, Bureau of
Mines); 9401.

TN23.U43 = [TN297] 622 s—de20  [622’.89] 91-33351 CIP



Report of Investigations 9401

Self-Contained Self-Rescuer Field Evaluation:
Results From 1982-90

By Nicholas Kyriazi and John P. Shubilla

UNITED STATES DEPARTMENT OF THE INTERIOR
Manuel Lujan, Jr., Secretary

BUREAU OF MINES
TS Ary, Director


BREATHING PRESSURE,

DRY-BULB TEMP, °C AV INHALED 0, , pet INHALED CO, , pet DURATION, min

mm H, 0

120

110

o 5
100 0

5, "42p 8” 8 88 c KEY
sor oe o no °? B Deployed unit

s © New unit

sof | & Treadmi
7oF
80 reer

Minimum

Average, new unit
Minimum, new unit
Minimum, treadmill

100 re
90 4
80 o a 4
70 ° .
[. oo ? KEY
a
ha 2 ao” Fe 7] @ Deployed unit
50 °° 4 oo Newunit
a
wf ° Treadmill
5
30 fo
> bd a9 to
* roiit roar
50 aa
45 2 coo,o oo 4
5 a 5 By
4ofo 0 of o PTF Be oo
o, ae KEY
35 3 Deployed unit
© New unit
30 4 Treadmit
25 4
20 bata
150 eT Tot
100 Fo o q
sof 228n8%oFo89 FopnotO8, SB Q0000,
° KEY
5 Exhalation
“ a,"
SOF an" ee = Inhalation
+100 Fa La} © Exhalation, new unit
“180 © Inhalation, new unit
4 Exhalation, treadmill
-200 & Inhalation, treadmill
-250
o2468

1012 1416 18 20 22 24 26 28 30 32 34

INDIVIDUAL UNITS

Figure 4.—Ocenco units, phase 2



AV INHALED 0, , pct INHALED CO, , pet DURATION, min

TEMP, °C

BREATHING PRESSURE,
mm H,0

120 s 1

110
100 4
Key
obo 3 Deployed unit
o o 2 4 © Newunit
8 8 Po
80F o o o o oo ° & Treadmill
p"se0 7 Jo .
70 o 68 a
60 1.
7 4 — T
6
5 4
4 ] KEY
3 3 Average
= Minimum
2 7 © Average, new unit
. ae © Minimum, new unit
Peo ge Sob geo ogg eG gd oy 2044 & Minimum, treadmil
. . °
oLitigieretst, sestas®
100 Pr ae
90
80
70 KEY
60 Deployed unit
50 © New unit
‘Treadmill
40
30 4
20 A ‘aan
50 pt 4
6 o ee
° fo ° KEY
4ofo o 8 a a2 0
5 2.00? Dry bulb
35 8 5 = Wet bulb
© Dry bulb, new unit
30 © Wet bulb, new unit
. . 4 Dry bulb, treadmill
28 8 . 4
. .
20 i re 1
150 -——+ 1 4
100
KEY
Exhalation
Inhalation

Exhalation, new unit
Inhalation, new unit
Exhalation, treadmill
Inhalation, treadmill

0 2 4 6 8 10 12 14 16 18 20 22 24 26
INDIVIDUAL UNITS

Figure 7.—Draeger units, phi