UNITED STATES BUREAU OF MINES

UNITED STATES DEPARTMENT OF THE INTERIOR

RI 9635 REPORT OF INVESTIGATIONS/1996

Self-Contained Self-Rescuer Field Evaluation: 

Fifth-Phase Results

By Nicholas Kyriazi and John P. Shubilla
U.S. Department of the Interior

Mission Statement

As the Nation’s principal conservation agency, the Department of the

Interior has responsibility for most of our nationally-owned public

lands and natural resources. This includes fostering sound use of our

land and water resources; protecting our fish, wildlife, and biological

diversity; preserving the environmental and cultural values of our

national parks and historical places; and providing for the enjoyment

of life through outdoor recreation. The Department assesses our

energy and mineral resources and works to ensure that their

development is in the best interests of all our people by encouraging

stewardship and citizen participation in their care. The Department

also has a major responsibility for American Indian reservation

communities and for people who live in island territories under U.S.

administration.
Report of Investigations 9635

Self-Contained Self-Rescuer Field Evaluation:

Fifth-Phase Results

By Nicholas Kyriazi and John P. Shubilla 

UNITED STATES DEPARTMENT OF THE INTERIOR

Bruce Babbitt, Secretary

BUREAU OF MINES

Rhea Lydia Graham, Director
International Standard Serial Number

ISSN 1066-5552
CONTENTS

Page

Abstract ...................................................................................... 1

Introduction .................................................................................... 2

Experimental procedure ............................................................................ 2

Test results and discussion .......................................................................... 4

CSE AU-9A1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

CSE SR-100 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Draeger OXY-SR 60B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

MSA Portal-Pack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Ocenco EBA 6.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

ILLUSTRATIONS

1. Breathing and metabolic simulator (BMS) at the Pittsburgh Research Center, Bruceton, PA ....................... 2

2. Cased and uncased CSE AU-9A1 self-rescuer ........................................................ 3

3. Cased and uncased CSE SR-100 self-rescuer ......................................................... 3

4. Cased and uncased Draeger OXY-SR 60B self-rescuer .................................................. 3

5. Cased and uncased MSA Portal-Pack self-rescuer ..................................................... 3

6. Cased and uncased Ocenco EBA 6.5 self-rescuer ...................................................... 3

7. CSE AU-9A1 test results ....................................................................... 5

8. CSE SR-100 test results . ....................................................................... 6

9. Draeger OXY-SR 60B test results ................................................................. 7

10. MSA Portal-Pack test results .................................................................... 8

11. Ocenco EBA 6.5 test results ..................................................................... 9

TABLES

1. Self-contained self-rescuers received for evaluation .................................................... 2

2. BMS metabolic workload ...................................................................... 4

3. Human subject workloads in treadmill tests .......................................................... 4

4. Wilcoxon rank-sum test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

5. CSE AU-9A1 CO breakthrough times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2

6. CSE SR-100 CO breakthrough times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2 

7. Draeger OXY-SR 60B CO breakthrough times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2

8. MSA Portal-Pack CO breakthrough times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2

9. Ocenco EBA 6.5 CO breakthrough times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2
UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT

h hour mL/min milliliter per minute

kg kilogram mm H O millimeter of water (pressure) 2

L liter ppm part per million

L/min liter per minute psi pound (force) per square inch

min minute % percent

mg/m milligram per cubic meter 3

 Mention of any company name or product does not constitute endorsement by the U.S. Department of Energy Pittsburgh Research

Center.

Visit our Mining Health and Safety Research site on the Internet, accessible via http://www.usbm.gov.
Biomedical engineer. 1

Engineering technician. 2

Pittsburgh Research Center, U.S. Department of Energy, Pittsburgh, PA.

This work originated under the U.S. Bureau of Mines prior to transferring to the U.S. Department of Energy on April 4, 1996. 3

SELF-CONTAINED SELF-RESCUER FIELD EVALUATION: 

FIFTH-PHASE RESULTS

By Nicholas Kyriazi and John P. Shubilla 1 2

ABSTRACT

A joint effort by the Pittsburgh Research Center (PRC) and the Mine Safety and Health Administration (MSHA) 3

was undertaken to determine how well self-contained self-rescuers (SCSR's), deployed in accordance with Federal

regulations (30 CFR 75.1714), held up in the underground environment with regard to both physical damage and

aging. This report presents findings regarding laboratory-tested SCSR's in the fifth phase of testing from mid-1993

to early 1996. The SCSR's were tested on human subjects and on a breathing and metabolic simulator (BMS) at

PRC. These results indicate that most of the apparatus, if they pass their inspection criteria, perform satisfactorily.
2

 Figure 1.—Breathing and metabolic simulator (BMS) at the Pittsburgh

Research Center, Bruceton, PA.

INTRODUCTION

On June 21, 1981, U.S. coal mine operators were required by

Federal law to make available to each underground coal miner a

self-contained self-rescuer (SCSR). The regulations at 30 CFR

75.1714 require that each person 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 1 h, as rated 2

by the certifying agencies—the National Institute for

Occupational Safety and Health (NIOSH) and the Mine Safety

and Health Administration (MSHA). The Pittsburgh Research

Center (PRC) is working jointly with MSHA in a long-term

evaluation of SCSR's now deployed in U.S. underground coal

mines. This work is in support of PRC’s Disaster Prevention

research program to improve safety for underground mine

workers. In this joint study, MSHA's responsibility is to locate

mines willing to participate and to procure from those mines the

SCSR's to be tested. PRC replaces those SCSR's with new

apparatus and tests the deployed SCSR's in its laboratories. The

objective of this long-term project is to evaluate the in-mine

operational durability of SCSR's. Of utmost concern is the

successful performance of any SCSR that passes its inspection

criteria. PRC is interested only in apparatus that pass their

inspection criteria. Such apparatus must function successfully to

enable a miner to escape safely during a mine emergency.

Apparatus that fail inspection criteria are expected to be removed

from service.

This study involves testing approximately 100 SCSR's in each

phase. This report describes findings in the fifth phase of testing

occurring from mid-1993 to early 1996. Previous reports

describe phases 1 through 4 (1-3). Testing was con- ducted 4

using a breathing and metabolic simulator (BMS) (figure 1) and

human subjects on a treadmill.

EXPERIMENTAL PROCEDURE

The SCSR's tested were manufactured by CSE Corp. (AU-9A1 manufacturers in the design of new apparatus. Ninety percent of

and SR-100), Draegerwerk AG (OXY-SR 60B), Mine Safety the apparatus were tested on the BMS; 10%, on human subjects.

Appliances Co., Inc. (MSA), (Portal-Pack) and Ocenco, Inc. One MSA Portal-Pack test was discarded because of instrument

(EBA 6.5). The SCSR’s were sampled according to estimated problems.

market share (table 1). These devices are pictured in figures 2

through 6. Some of the first-generation SCSR’s are no longer

being used underground (MSA 60-min SCSR and PASS 700);

others are being phased out (CSE AU-9A1 and Draeger OXY-SR

60B). The service life of the CSE AU-9A1 expired during this

phase, so that we were able to obtain only part of our target

number of units for testing. We included apparatus being phased

out because information that we ob- tain about these 15-year-old

apparatus may help the

 Italic numbers in parentheses refer to items in the list of references at the 4

end of this report.

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

Apparatus Quantity tested

CSE AU-9A1 .............................. 7

CSE SR-100 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Draeger OXY-SR 60B . . . . . . . . . . . . . . . . . . . . . . . 20

MSA Portal-Pack . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Ocenco EBA 6.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
3

Figure 2.—Cased and uncased CSE AU-9A1 self-rescuer.

Figure 3.—Cased and uncased CSE SR-100 self-rescuer.

Figure 4.—Cased and uncased Draeger OXY-SR 60B self-rescuer.

Figure 5.—Cased and uncased MSA Portal-Pack self-rescuer.

Figure 6.—Cased and uncased Ocenco EBA 6.5 self-rescuer.

The O 2 constant-flow rate is checked on compressed-O2

apparatus; the NIOSH-required flow is 1.5 L/min at ambient

temperature and pressure (at NIOSH in Morgantown, WV), dry

(ATPD).

All apparatus are checked for breathing circuit leak-tightness

after opening. The leak test used is that recom-mended for the

CSE AU-9A1 by the manufacturer; this test is identical to that

required by Draeger for its BG-174 rescue breathing apparatus. It

is performed to determine how well the apparatus isolates the user

from the environment, which is assumed to be irrespirable.

Passing the test, however, is not a requirement of the regulations.

The test permits a decay in breathing circuit pressure from &70 to

&60 mm H O in 1 min. This is equivalent to a leak rate of 2

approximately 1 mL/min (all volumes at standard temperature and

pressure, dry, unless otherwise stated) given an internal volume for

both the apparatus and test stand of 1 L. To give this some

perspective, an in-leakage rate of 1 mL/min in a 10% CO

atmosphere during a peak inhalation flow rate of 89 L/min, which

occurs in the BMS workload, would result in a 1-ppm

concentration of CO in the inhalation gas stream. The 8-h

threshold limit value for CO is 50 ppm. The Draeger/CSE leak

test, therefore, can be considered very conservative.
4

MSHA selected the participating mines with regard to type of The stressors monitored were inhaled levels of CO and O ,

mining operation and SCSR deployment mode in order to obtain end-of-breath inhalation wet- and dry-bulb temperatures, and

a representative cross section of U.S. mines. De-ployment modes inhalation and exhalation peak breathing pressures in both the

sampled were— BMS and treadmill testing. In the treadmill testing, minimum

C Permanently stored (42%); inhaled levels of CO and maximum inhaled levels of O were

C Single-shift, carried and stored (24%); measured. In the BMS testing, however, average inhaled levels of

C Stored on a mining machine (rubber-tired coal shuttle, both CO and O were measured. Average inhaled gas levels

locomotive, or man-trip) (21%); and include the effect of apparatus dead space, whereas minimum

C Single-shift, belt-worn (13%). values of CO , for example, are only the lowest level of gas

Mine types sampled were conventional (28%), continuous (64%), concentration during inhalation. The BMS measures average

and longwall (8%). inhaled values by electronically summing all of the CO and O of

The BMS test consisted of the average metabolic work rate each inhalation cycle, weighted by the instantaneous flow rate.

exhibited by the 50th-percentile miner weighing 87 kg while The BMS also measures minimum inhaled CO levels.

performing the 1-h man test 4 as described in 42 CFR 84. The Tests on the BMS were terminated upon exhaustion of

BMS metabolic workload is presented in table 2. The CO the O supply as indicated by negative pressures reaching 2

production rate was increased to 1.30 L/min from 1.10 L/min in -200 mm H O coinciding with an empty breathing bag. Treadmill

the previous several phases. This was done to reflect the finding tests were terminated in the same manner or if inhaled minimum

that our new set of human test subjects had higher such rates than CO levels reached 4%, if maximum O levels fell below 15%, or

our previous test subjects. In the treadmill testing, the subjects if the test subject stopped because of subjectively high breathing

walked at whatever speed and grade resulted in an O pressures or temperatures. 2

consumption rate of 1.35 L/min. The CO production rate, 2

ventilation rate, and respiratory frequency varied among human

test subjects; these are listed in table 3.

Table 2.—BMS metabolic workload

O consumption rate ....................... L/min . . 2 1.35

CO production rate ........................ L/min . . 2 1.30

Ventilation rate ............................ L/min . . 30.0

Tidal volume . . . . . . . . . . . . . . . . . . . . . . . . . L per breath . . 1.68

Respiratory frequency .............. breaths per min . . 17.9

Peak respiratory flow rate:

Inhalation ............................. L/min . . 89.0

Exhalation ............................ L/min . . 71.0

2 2

2 2

2 2

2

2 2

2

2

2

2 2

Table 3.—Human subject workloads in treadmill tests

 Subject VCO , V , RF, 2

L/min L/min breaths per min

e

A ............... 1.25 31 26

B ............... 1.18 22 10

C.............. 1.35 25 10

D.............. 1.15 30 9

VCO = CO production rate. 2 2

V = Ventilation rate. e

RF = Respiratory frequency. 

TEST RESULTS AND DISCUSSION

Experience with each model of apparatus is discussed Missing data points for wet-bulb temperature indicate equip-ment

separately. The minute-average values of the monitored stressors malfunction.

were averaged over the entire test duration and are presented The Wilcoxon rank-sum test was performed for each monitored

graphically (figures 7 through 11) for each apparatus by stressor. stressor to determine whether the deployed units behaved

The values for new units tested on the BMS can be compared with differently from new units. It tests the hypothesis that the two

the values for deployed units tested on the BMS and, to some samples are from populations with the same mean. The values

extent, with deployed units tested on human subjects on a from both samples are ranked in ascending order of magnitude. If

treadmill, which are plotted afterward. Because human subjects the sum of the ranks of the smaller sample (T) (in this case, new

may differ from each other and from the BMS in terms of VCO , units) falls within the acceptable range for the given sample sizes, 2

V , and respiratory frequency, all of which affect apparatus then there is not sufficient evidence at the specified probability e

duration as well as all of the monitored stressors, these tests cannot level (P ' 0.05, two-sided) to say that the means of the two

be considered equivalent to the BMS tests even though the O samples differ. The rank-sum test does not rely upon the 2

consumption rate is the same. assumptions that either the new- or deployed-unit 
5

Figure 7.—CSE AU-9A1 test results.
6

Figure 8.—CSE SR-100 test results.
7

Figure 9.—Draeger OXY-SR 60B test results.
8

Figure 10.—MSA Portal-Pack test results.
9

Figure 11.—Ocenco EBA 6.5 test results.
10

data are normal distributions or that they have identical variances, treadmill tests than in the BMS tests. These could be caused by

as does the t-test for two populations of independent samples. One higher bed resistances or higher peak flow rates in the human test

limitation of the Wilcoxon rank-sum test is that it does not subjects than in the BMS. At the end of the first treadmill test,

distinguish between large and small differences in values. The human subject A was experiencing minimum inhaled CO levels

results of the two-sided, P ' 0.05, Wilcoxon rank-sum tests are of 3.6%, with unmeasured average inhaled levels even higher.

presented in table 4. The probability of T, the rank sum of the new Higher ventilation rates caused by the elevated CO levels is a

units, falling outside the given range is 0.05 if the populations have reasonable explanation for these high breathing pressures. The

the same mean. second treadmill test pressures were even higher, but these occurred

CSE AU-9A1 rates are higher than those of the BMS or the chemical bed had

Three of seven deployed apparatus passed the leak-tightness than-average pressures, which cannot be attributed to higher

test, and all three new units passed. ventilation rates. The apparatus for BMS test 15 had been carried

The Wilcoxon rank-sum tests for the inhalation and ex-halation into the mine and set on a mining machine daily, but six others

peak pressures showed higher values for new than deployed units were as well. This does not mean, however, that all units deployed

(table 4). If this is the result of settling of the chemical absorbent, in a certain way were subjected to equivalent shock and vibration.

the inhaled CO values might be expected to be higher due to air This particular unit may have suffered greater environmental 2

channeling, and they are (table 4 and figure 7), but not statistically impact than the others, or it may have been different in

significantly higher. manufacture. The inhalation pressure reached our normal negativeAll of the apparatus tested on the BMS, new and deployed, pressure termination limit of &200 mm H O at 58 min.

reached 4% CO (average inhaled) before the O supply was Termination was called, instead, when the bag was flat. 2 2

expended (table 5); one occurred before 60 min. They were

permitted to continue until the O supply was expended. The one 2 DRAEGER OXY-SR 60B

apparatus tested on a human subject (subject B) reached 4%

(minimum inhaled) just as the O supply became expended. This Eighteen of nineteen deployed and two of three new units 2

better performance can be explained by the fact that subject B had passed the leak-tightness test.

a VCO of only 1.18 L/min compared with the 1.30 L/min of the The Wilcoxon rank-sum tests showed that both the wet- and 2

BMS. The CO -absorbent canister is simply undersized compared dry-bulb temperatures of new units border on being sig-nificantly 2

with the O supply. The result of high inhaled levels of CO will lower than deployed units. Two of the tests of deployed apparatus 2 2

be increased ventilation rates in most users. (units 14 and 18) showed wet-bulb temperatures much higher than

The O gauge of one unit read 500 psi when empty. Such an the others. One treadmill test also showed a wet-bulb temperature 2

incident would have no negative consequences unless an escaping as high. These imply increased humidity resulting from the various

user decided to remain in an area with an irrespirable atmosphere chemical processes occurring within the bed and its interaction with

longer than necessary for some reason based on the gauge reading. the user. Regardless of the cause and whether or not it resulted

CSE SR-100 minimal: the inhaled wet-bulb temperatures never exceeded the

Seventeen of twenty deployed and three of four new apparatus Five deployed units reached 4% CO before the O supply was

passed the leak-tightness test. expended; all occurred before 60 min. One of these was on a

The Wilcoxon rank-sum test for average inhaled CO showed treadmill test; the others, the BMS (table 7). One new unit tested 2

a statistically significant difference between new and deployed on the BMS also experienced CO breakthrough.

units, with deployed units having higher values than new ones Although the Wilcoxon rank-sum test showed that deployed

(table 4). Table 6 shows that 16 of 20 units ex-perienced CO apparatus, as a group, did not differ with regard to CO levels, the 2

breakthrough before expenditure of the O supply; 10 of these third BMS-tested deployed unit had much higher CO levels than 2

occurred before 60 min. Of the new units, two of four experienced other deployed units, as can be seen in figure 9. Average inhaled

premature breakthrough, but only by several minutes, and neither CO levels reached 4% at 47 min and 14% at 60 min. 

before 60 min. As mentioned above, the result of high inhaled

levels of CO will be increased ventilation rates in most users. 2

Increased ventilation rates will result in higher breathing pressures

experienced by the user. Breathing pressures in the SR-100

increase rapidly toward end of life, even in new apparatus.

Elevated CO levels will ac-celerate this rise. The termination of 2

one treadmill test (human subject C) at 55 min was for high

breathing pressures (%250 to &360 mm H O) even though there 2

was sufficient volume in the breathing bag to permit continued use.

This occurred with minimum inhaled CO levels of only 0.6%. 2

Figure 8 shows higher breathing pressures in the human subject

2

2

with low CO levels. Either the test subject’s normal peak flow 2

greater-than-average resistance. BMS test 15 also exhibited greater2

from damage while deployed, the impact on a user would be

human tolerance level in any of the tests.

2 2

2

2

2

2
11
12

Table 5.—CSE AU-9A1 CO breakthrough times, minutes 2

Type of unit and test method CO Final 2

breakthrough termination

Deployed: BMS . . . . . . . . . . . . . . . . 61 89

69 96

66 84

74 91

57 68

60 88

Deployed: Human subject on

 treadmill . . . . . . . . . . . . . . . . . . . . . 84 84

New: BMS . . . . . . . . . . . . . . . . . . . . 75 84

70 93

75 91

Table 6.—CSE SR-100 CO breakthrough times, minutes 2

Type of unit and test method CO breakthrough 2

Final

termination

Deployed: BMS . . . . . . . . . . . . . 23 68

61 62

60 67

65 66

59 64

44 73

47 68

48 72

46 66

31 70

60 67

62 64

70 73

58 68

28 68

35 68

New: BMS . . . . . . . . . . . . . . . . . 64 65

63 66

Table 7.—Draeger OXY-SR 60B CO breakthrough 2

 times, minutes

Type of unit and test method CO Final 2

breakthrough termination

Deployed: BMS . . . . . . . . . . . . . . . . 51 65

55 66

47 68

53 64

Deployed: Human subject on

 treadmill . . . . . . . . . . . . . . . . . . . . . 51 51

New: BMS . . . . . . . . . . . . . . . . . . . . 66 70

This unit was carried and stored daily, as were most of the other

deployed units.

As with CO levels, the Wilcoxon rank-sum test showed that 2

deployed apparatus, as a group, did not differ from new units with

regard to exhalation pressures. However, figure 9 shows units 13

and 14 having higher exhalation pressures than other deployed

units. The pressures were normal (around 50 mm H O) up to 2

50 min, then increased sharply. By the end of the test at 70 min,

unit 13 reached 170 mm H O; unit 14 reached 430 mm H O at 2 2

73 min. Unit 14 would have challenged a wearer by the end. The

second treadmill test had a similar exhaled pressure average. All

three of these apparatus were the only ones with serial numbers in

the 32,000 range. Whether or not the higher breathing resistances

were the result of damage suffered during deployment or of

manufacture or both, the user would have been impaired, if at all,

only at the end of the apparatus’ service life. In the case of the

apparatus with the highest pressures, the user would have been

inclined 

to either modify his/her breathing or slow down to decrease peak

flow rates in order to continue use until the complete expenditure

of the O supply. 2

MSA PORTAL-PACK

Six of eight deployed and two of three new apparatus tested for

leaks passed.

The Wilcoxon rank-sum tests showed that new units had

significantly higher inhalation pressures than deployed units. This

would not negatively impact the user.

Six deployed units tested on the BMS reached 4% CO before 2

the O supply was expended; two of these occurred before 60 min 2

(table 8). All three new units tested on the BMS also experienced

CO breakthrough; two of these occurred before 60 min. 2

Table 8.—MSA Portal-Pack CO breakthrough times, minutes 2

Type of unit and test method CO breakthrough Final 2

termination

Deployed: BMS . . . . . . . . . . . . 69 76

62 70

49 67

63 65

52 70

72 76

New: BMS . . . . . . . . . . . . . . . . 49 71

 54 74

64 69

We discovered that the chlorate candles of some units emitted

a white smoke when activated. This caused two con-cerns: the

reaction of the user to the sight of the smoke and the composition

of the smoke. The gas produced from the candles of several units

was sampled and analyzed by MSHA’s Physical and Toxic Agents

Div. These opened and activated units were sealed for later testing

with manual starts; other than lower O levels, they functioned 2

satisfactorily as can be seen in figure 10. Both particulate and

gaseous components were analyzed. The particulate sample had

sodium and potassium salts as the primary contaminants. In

addition, a barium salt, with an 8-h threshold limit value of 0.5

mg/m , was measured at 1.56 mg/m . The gas analysis also 3 3

detected an unquantified level of benzene. NIOSH was notified of

our findings. MSA performed its own gas analysis and detected

benzene in one sample, but in 
13

a concentration greatly below the short-term exposure limit. We was reported to NIOSH and MSHA. Ocenco now inspects 100%

are less concerned about the short-term exposure to these

contaminants than user response to visible white smoke. MSA’s

training videotape mentions the possibility of smoke; the written

manual does not. A special notification from the manufacturer will

be mailed to all users, or the manual will be updated to include

mention of the smoke.

OCENCO EBA 6.5

Four of 39 deployed apparatus tested for breathing circuit

tightness passed the leak test, while none of the three new apparatus

passed. Many units passed the test when their relief valves were

capped, however, implying backflow through the valves.

The Wilcoxon rank-sum tests showed that, in all categories, new

units could not be distinguished from deployed units.

The high inhalation pressures exhibited by some of the

apparatus on the BMS (figure 11) were caused by activation of the

demand valves, some of which are relatively stiff. When the

demand valve is not required, the inhalation pressures are low,

reflecting low system resistance. The demand valve is called into

use when the O supply rate falls below the O consumption rate. 2 2

Whether and when this happens depends on the O regulator and 2

its factory setting, both of which can vary significantly. The

average initial O flow of the apparatus tested was 1.82 L/min 2

ATPD, ranging from 1.53 to 3.66 L/min. The 3.66-L/min flow

lowered somewhat after 10 min, such that the final duration for this

apparatus was 89 min. Another apparatus (unit 28 in figure 11)

had an initial O flow of 2.4 L/min, but this increased after 5 min, 2

as evidenced by relief valve use; this resulted in a duration of

36 min. The short duration and high O flow rate resulted in low 2

inhalation temperatures and high exhalation pressures, as can be

seen in figure 11. This incident 

of the O regulators. 2

Sixteen deployed units tested on the BMS reached 4% CO2

before the O supply was expended; none occurred before 60 min 2

(table 9). Several deployed units had much higher CO levels than 2

the rest, as can be seen in figure 11. User response would be as

mentioned earlier.

Table 9.—Ocenco EBA 6.5 CO breakthrough times, minutes 2

Type of unit and test method CO breakthrough 2

Final

termination

Deployed: BMS . . . . . . . . . . . . 96 101

105 108

96 103

99 101

77 107

87 111

94 103

104 109

100 107

95 98

87 110

97 103

98 104

96 101

88 103

79 108

The O gauges of two units read 500 and 1,000 psi when their 2

cylinders were empty.

When the cylinder valve was opened on one unit to measure its

O flow, there was a surge of O such that the friction-fit 2 2

connecting hose to the flow-measurement instrument was blown

off. The O gauge registered a 75-psi drop in cylinder pressure. 2

This phenomenon did not recur when the cylinder valve was

reopened for testing.

CONCLUSIONS

The results of this fifth-phase SCSR test study at PRC suggest apparatus that possibly suffered extreme abuse and exhibited poor

that the large majority of SCSR's that pass their inspection criteria performance, yet passed inspection criteria. Examples include a

can be relied upon to provide a safe level of life support capability Draeger OXY-SR 60B with high CO levels (figto allow miners to escape safely during a mine emergency. ure 9), another OXY-SR 60B with high exhalation pressures

However, the mining environment appears to have caused some (figure 9), and several Ocenco EBA 6.5's with high CO levels

performance degradation in the CSE SR-100: CO levels are (figure 11). Although the Draeger OXY-SR 60B’s are no longer 2 

higher in deployed units than new ones (table 4 and figure 8). No in use, the Ocenco EBA 6.5's continue to be used and will be

statistically significant worsening in any performance category was monitored for further signs of deterioration.

detected in any other apparatus. The incidents with cylinder gauges on the CSE AU-9A1 and

Because the Wilcoxon rank-sum test, by its nature, detects small the Ocenco EBA 6.5 indicating 500 psi and higher with empty

changes in large numbers of units and tends to ignore large changes cylinders suggest that their accuracy should not be relied upon and

in small numbers of units, we should also pay attention to reaffirms that SCSR’s should be used only for emergency escape,

performance of individual units. Of concern are not for reentry into irrespirable atmospheres based on 

2

2
14

perceived remaining duration. Apparatus should be worn until eliminated, this phenomenon must be clearly mentioned during

reaching safety, then removed. training.

The smoke sometimes emitted from the chlorate candle of the The short-duration Ocenco EBA 6.5 caused by the faulty O

MSA Portal-Pack may suggest that the apparatus is regulator shows the importance of 100% inspection of all critical

malfunctioning and lead the user to abandon it. If not SCSR components.

2

ACKNOWLEDGMENTS

The authors thank Don Peiffer, physical scientist, MSHA Approval and Certification Center, Triadelphia, WV, for help with procuring

the deployed SCSR’s.

REFERENCES

1. Kyriazi, N., J. G. Kovac, J. Shubilla, W. Duerr, and J. Kravitz. Self- 3. Kyriazi, N., and J. P. Shubilla. Self-Contained Self-Rescuer Field

Contained Self-Rescuer Field Evaluation: First-Year Results of 5-Year Study. Evaluation: Fourth-Phase Results. USBM RI 9499, 1994, 10 pp.

USBM RI 9051, 1986, 12 pp.

2. Kyriazi, N., and J. P. Shubilla. Self-Contained Self-Rescuer Field

Evaluation: Results From 1982-90. USBM RI 9401, 1992, 18 pp.