IC 9451 INFORMATION CIRCULAR/2000

Self-Contained Self-Rescuer Field Evaluation:

Sixth-Phase Results

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Public Health Service

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health
Information Circular 9451

Self-Contained Self-Rescuer Field Evaluation:

Sixth-Phase Results

By Nicholas Kyriazi and John P. Shubilla

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

Public Health Service

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health

Pittsburgh Research Laboratory

Pittsburgh, PA

July 2000
International Standard Serial Number

ISSN 1066-5552
CONTENTS

Page

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

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

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

Results and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

CSE SR-100 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Draeger OXY K Plus ......................................................................... 5

MSA Portal-Pack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Ocenco EBA 6.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Ocenco M-20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

ILLUSTRATIONS

1. Breathing and metabolic simulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

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

3. Cased and uncased Draeger OXY K Plus self-rescuer ............................................ 3

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

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

6. Cased and uncased Ocenco M-20 self-rescuer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

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

8. Draeger OXY K Plus test results ............................................................. 7

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

10. Ocenco EBA 6.5 test results ................................................................ 9

11. Ocenco —20 test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

TABLES

1. SCSRs received for evaluation .............................................................. 2

2. BMS and human-subject metabolic parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3. Wilcoxon rank-sum test results .............................................................. 5

4. CSE SR-100 CO2 breakthrough times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5. Draeger OXY K Plus CO2 breakthrough times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

6. MSA Portal-Pack CO2 breakthrough times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

7. Ocenco EBA 6.5 CO2 breakthrough times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

8. Ocenco M-20 CO2 breakthrough times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT

breaths/min breaths per minute L/min liter(s) per minute

hr hour(s) min minute(s)

kg kilogram(s) mL/min milliliter(s) per minute

L liter(s) mm H2O millimeter(s) of water (pressure)

L/breath liter(s) per breath ppm parts per million
SELF-CONTAINED SELF-RESCUER FIELD EVALUATION:

SIXTH-PHASE RESULTS

By Nicholas Kyriazi1 and John P. Shubilla2

ABSTRACT

The National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Laboratory, has

undertaken a study to determine how well self-contained self-rescuers (SCSRs), deployed in accordance with

Federal regulations (30 CFR 75.1714), hold up in the underground environment with regard to both physical

damage and aging. This report presents findings regarding laboratory-tested SCSRs in the sixth phase of

testing from mid-1996 to early 1998. The SCSRs were tested on human subjects and on a breathing and

metabolic simulator. These results indicate that most of the apparatus, if they pass their inspection criteria,

perform satisfactorily. However, the deployed CSE SR-100s exhibited significantly higher inhaled CO2 levels

than new units, as in the previous phase. This will cause higher ventilation rates in most users, which will, in

turn, result in higher breathing pressures, possibly causing users to prematurely remove the apparatus. CSE

Corp. has developed a noise test that can identify apparatus suffering from chemical-bed degradation causing

the early CO2 breakthrough. This test was added to the inspection criteria for the SR-100. In addition, several

of the MSA Portal-Packs that passed their inspection criteria were found to have KO2 dust in their

mouthpieces. Further investigations by NIOSH and the Mine Safety and Health Administration confirmed

these findings, which resulted in the decertification of the apparatus and their removal from service.

1

Biomedical engineer.

2

Engineering technician.

Pittsburgh Research Laboratory, National Institute for Occupational Safety and Health, Pittsburgh, PA.
2

Figure 1.–Breathing and metabolic simulator at the NIOSH

Pittsburgh Research Laboratory, Bruceton, PA.

INTRODUCTION

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

to make available to each underground coal miner a

self-contained self-rescuer (SCSR). The regulations (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 O2 source for at least 1 hr, as

rated by the certifying agencies—the National Institute for

Occupational Safety and Health (NIOSH) in Morgantown, WV,

and the Mine Safety and Health Administration (MSHA). The

NIOSH Pittsburgh Research Laboratory (PRL) is conducting a

long-term evaluation of SCSRs deployed in underground coal

mines. This work is in support of PRL's disaster prevention research program to improve safety for underground mine

workers. PRL locates mines willing to participate in the study

and trades deployed SCSRs for new ones. PRL then tests the

deployed SCSRs. The objective of this long-term program is to

evaluate the in-mine operational durability of deployed SCSRs.

Of utmost concern is the successful performance of any SCSR

that passes its inspection criteria. PRL 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 SCSRs in

each phase. This report describes findings in the sixth phase of

testing occurring from mid-1996 through early 1998. Previous

reports describe phases 1 through 5 [Kyriazi et al. 1986; Kyriazi

and Shubilla 1992, 1994, 1996]. Testing was conducted using

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

human subjects on a treadmill.

EXPERIMENTAL PROCEDURE

The SCSRs tested were manufactured by CSE Corp.,

Draegerwerk AG, Mine Safety Appliances Co., Inc. (MSA),

and Ocenco, Inc., and were sampled according to estimated

market share (table 1). The apparatus are shown in figures 2

through 6. Ninety percent of the apparatus were tested on the

BMS; 10%, on human subjects.

The O2 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 recommended

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

performed to determine how well the apparatus isolates the user

from the environment, which may be irrespirable in an emergency. Passing the test is not a requirement of the regulations,

however. The test permits a decay in breathing circuit pressure

Table 1.—SCSRs received for evaluation

Apparatus No.

received

 No.

tested

CSE SR-100 . . . . . . . . 30 27

Draeger OXY K Plus . . 10 9

MSA PORTAL-PACK 10 8

Ocenco EBA 6.5 . . . . . 40 38

Ocenco M-20 . . . . . . . 10 10

 Total . . . . . . . . . . . . 100 92

from &70 to &60 mm H2O in 1 min. We have determined that

just passing the test is equivalent to a leak rate of approximately

1 mL/min given an internal volume for both the apparatus and

test stand of 1 L (all volumes in this report are given at standard

temperature and pressure, dry, unless otherwise noted). To give

this some perspective, an in-leakage rate of 87 mL/min in a 10%

CO atmosphere at a peak inhalation flow rate of 250 L/min

would result in an 8-hr threshold limit value (TLV) for CO of
3

Figure 2.—Cased and uncased CSE SR-100 self-rescuer.

Figure 3.—Cased and uncased Draeger OXY K Plus self-rescuer.

Figure 4.—Cased and uncased MSA Portal-Pack self-rescuer.

Figure 5.—Cased and uncased Ocenco EBA 6.5 self-rescuer.

Figure 6.—Cased and uncased Ocenco M-20 self-rescuer.

35 ppm. The 250 L/min peak inhalation flow rate is used because this occurs at roughly a 100 L/min ventilation rate, the

highest likely rate that can reasonably be expected of a user. At

such a maximal work rate, inhalation pressure should not

exceed &300 mm H2O, the highest negative pressure tolerated

by 80% of test subjects in a recent study [Hodgson 1993]. At

a leak test pressure of &70 mm H2O, the proportional in-leakage

rate resulting in an 8-hr TLV would be 20 mL/min at a peak

inhalation flow rate of 58 L/min. The Draeger leak test, therefore, can be considered very conservative.

PRL selected the participating mines with regard to type of

mining operation, coalbed height, and SCSR deployment mode

in order to obtain a wide range of deployment impact. Deployment modes included permanent storage on the ground, on

a mantrip or mining machine, or belt-worn.

The BMS test consisted of the average metabolic work rate

exhibited by the 50th-percentile miner weighing 87 kg while

performing the 1-hr man test 4 as described in 42 CFR 84. In

the treadmill testing, the human subjects walked at whatever

speed and grade resulted in an O2 consumption rate of

1.35 L/min. The CO2 production rate, ventilation rate, and respiratory frequency varied in the test subjects. The metabolic

workloads are given in table 2.

The parameters monitored were inhaled levels of CO2 and

O2, end-of-inhalation wet- and dry-bulb temperatures, and

inhalation and exhalation peak breathing pressures in both the

BMS and treadmill testing. In the BMS testing, however,

average inhaled levels of gas concentration were measured,

as opposed to minimum values of CO2 and maximum values of

O2 in the treadmill testing. Average inhaled gas levels include

the effect of apparatus dead space, whereas minimum values of
4

Table 2.—BMS and human-subject metabolic parameters

Metabolic workload BMS Subject

A

Subject

B

Subject

C

O2 consumption rate . . . . . . . . L/min . . 1.35 1.35 1.35 1.35 

CO2 production rate . . . . . . . . . L/min . . 1.30 1.12 1.18 1.15 

Ventilation rate . . . . . . . . . . . . L/min . . 30.0 27 22 30 

Tidal volume . . . . . . . . . . . . L/breath . . 1.68 1.59 2.20 3.33 

Respiratory frequency . . . breaths/min . . 17.9 17 10 9 

Peak respiratory flow rate:

 Inhalation . . . . . . . . . . . . . . L/min . . 89 (1

) (1) (1) 

 Exhalation . . . . . . . . . . . . . . L/min . . 71 (1

) (1) (1) 1

Not measured.

CO2, for example, are only the lowest level of gas concentration

during inhalation. The BMS measures average inhaled values

by electronically summing all of the CO2 and O2 over each inhalation cycle, weighted by the instantaneous flow rate. The

BMS also measures minimum inhaled CO2 levels.

Tests on the BMS were terminated upon exhaustion of the

O2 supply as indicated by negative pressures reaching &200 mm

H2O, coinciding with an empty breathing bag. Some BMS tests

were terminated when average inhaled CO2 levels reached 10%

or O2 levels went below 15%. Treadmill tests were terminated

in the same manner, but using a limit of 4% minimum inhaled

CO2 or if the test subject stopped because of subjectively high

breathing pressures or temperatures. Because the BMS is unaffected by high CO2 levels, in order to gain more information

about the performance of an apparatus, tests were continued to

the higher CO2 level in BMS testing.

RESULTS AND DISCUSSIONS

Experience with each model of apparatus is discussed

separately. The minute-average values of the monitored stressors

were averaged over the entire test duration and are presented

graphically (figures 7-11) for each apparatus by stressor. The

values for new units tested on the BMS can be compared with

those for deployed units tested on the BMS and, to some extent,

with those for deployed units tested on human subjects on a

treadmill, which are plotted afterward. Because human subjects

may differ from each other and from the BMS in terms of CO2

production rate, ventilation rate, and respiratory frequency, all of

which affect apparatus duration as well as all of the monitored

stressors, these tests cannot be considered equivalent to the BMS

tests even though the O2 consumption rate is the same. Missing

data points for wet-bulb temperature indicate equipment malfunction or inability to instrument apparatus.

The Wilcoxon rank-sum test was performed for each

monitored stressor to determine whether the deployed units

behaved differently from new units. It 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 case, new units) falls within the acceptable range for the

given sample sizes, then there is not sufficient evidence at the

specified probability level (α ' .05, two-sided) to say that the

means of the two samples differ. The rank-sum test does not

rely upon the assumptions that either the new- or deployed-unit

data are normal distributions or that they have identical

variances, as does the t-test for two populations of independent

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, α ' 0.05, Wilcoxon ranksum tests are presented in table 3. The probability of T, the

rank sum of the new units, falling outside the given range is

0.05 if the populations have the same mean.

CSE SR-100

Three deployed apparatus tests had instrument problems,

and their data were not used. Regarding leak testing, 17 of

25 deployed units passed, and 3 of 4 new apparatus passed.

The Wilcoxon rank-sum test for average inhaled CO2

showed a significant difference between new and deployed

units, with deployed units having higher values than new ones

(table 3). This was also found to be true in the previous phase

of this study [Kyriazi and Shubilla 1996].

Table 4 shows that 19 of 24 apparatus tested on the BMS

experienced CO2 breakthrough before expenditure of the O2

supply; 15 of these occurred before 60 min. Of the new units,

two of four experienced premature breakthrough, but only by

several minutes and neither before 60 min. The effect of high

inhaled levels of CO2 will be increased ventilation rates in most

users. Increased ventilation rates will result in higher breathing

pressures experienced by the user, possibly resulting in premature removal of the apparatus. Breathing pressures in the

SR-100 increase rapidly toward end-of-life even in new apparatus; elevated CO2 levels will accelerate this rise.
5

Table 3.—Wilcoxon rank-sum test results

Apparatus Duration Average

inhaled CO2

Average

inhaled O2

Wet-bulb

temperature

Dry-bulb

temperature

Inhalation

pressure

Exhalation

pressure

Range T Range T Range T Range T Range T Range T Range T

SR-100 . . . . . . . 28-88 55 28-88 26 28-88 44 28-88 55 28-88 75 28-88 28 28-88 31

OXY K Plus . . . 8-28 7 7-26 16 8-28 14 8-28 11 8-28 21 8-28 10 8-28 11

Portal-Pack . . . . 7-26 15 7-26 20 7-26 24 7-26 21 7-26 25 7-26 23 7-26 21

EBA 6.5 . . . . . . . 13-53 23 13-53 18 13-53 19 13-53 18 13-53 26 13-53 46 13-53 43

M-20 . . . . . . . . . 8-31 19 8-31 14 8-31 18 8-31 33 8-31 33 8-31 18 8-31 12

T ' Sum of the ranks of the smaller sample (new units).

Table 4.—CSE SR-100 CO2 breakthrough times, minutes

Type of unit and

test method

CO2

breakthrough

time

Test

duration

Maximum

 CO2

Deployed: BMS . . . . . . . . . . . 29 63 7.9

42 62 8.1

12 50 10.2

32 51 8.5

55 65 7.3

56 65 6.5

59 65 6.1

57 64 8.0

60 73 9.9

46 65 7.3

49 66 8.6

57 65 7.0

37 63 10.6

34 66 10.3

34 59 10.5

69 70 4.8

29 71 11.9

66 71 6

69 69 4.3

Deployed: Human subject

 on treadmill . . . . . . . . . . . . . 60 60 4

New: BMS . . . . . . . . . . . . . . . 64 65 4.8

63 66 5.1

CO2 breakthrough for BMS - 4% average inhaled; for treadmill - 4% minimum

inhaled. 

The termination of one treadmill test (human subject C) at

40 min was for high breathing pressures (&480 to %210 mm

H2O) even though there was sufficient volume in the breathing

bag to permit continued use. This occurred with minimum inhaled CO2 levels of only 0.9%. This unit was dissected at CSE

Corp.'s facility and found to have a canister dented on three

sides; this damage was not evident from external inspection

according to present inspection criteria. As a result of this

incident, the manufacturer has added an inspection criterion to

closely inspect the end-cap seals for damage. Another treadmill

test was terminated at 60 min when the minimum inhaled CO2

level reached 4% with unmeasured average inhaled level

necessarily higher. This test subject also coughed repeatedly at

the start of the test, but was able to continue.

One unit had to be manually started by exhaling several

times into the mouthpiece when the starter O2 cylinder provided

no O2 to the breathing circuit.

Two units had breathing hoses that were stuck together and

required some effort to open them for use. One also required

some effort to remove the case top and bottom.

DRAEGER OXY K PLUS

All deployed and new units tested failed the leak-tightness

test. The Wilcoxon rank-sum tests showed that the durations of

the new units were statistically significantly lower than those of

the deployed units. If deployment caused the bed chemical to

break into smaller particles, resulting in more surface area, this

could cause better chemical utilization, resulting in longer duration. It might also result in higher breathing pressures. Since

this was not found to be the case, longer durations on deployed

apparatus are not viewed as a problem.

One deployed apparatus reached an average inhaled CO2

level of 4% at 81 min before exhaustion of the oxygen supply at

83 min (table 5). No new units experienced CO2 breakthrough.

Table 5.—Draeger OXY K Plus CO2 breakthrough times, minutes

Type of unit and

test method

CO2 breakthrough

 time

Test

 duration

Maximum

CO2

Deployed: BMS . . . 81 83 4.4

CO2 breakthrough for BMS - 4% average inhaled; for treadmill - 4%

minimum inhaled.
6

Figure 7.—CSE SR-100 test results.
7

Figure 8.—Draeger OXY K Plus test results.
8

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

Figure 10.—Ocenco EBA 6.5 test results.
10

Figure 11.—Ocenco M-20 test results.
11

MSA PORTAL-PACK

Three deployed units evidenced potassium superoxide

(KO2) dust in their mouthpieces; two of these were dissected without testing at MSHA's request to inspect for

damage. The other unit was tested on the BMS and was

found to perform normally. Exhaling 5 to 10 times into the

breathing hose of an apparatus found to have fine dust in

the mouthpiece wets down the dust, permitting the apparatus to be worn. However, the certification agencies, after inspecting a number of other units, decided that this was

too much to expect of a user in an emergency and decertified the apparatus after they could all be replaced with

the new MSA Life-Saver 60 or other certified SCSR.

Of seven deployed apparatus tested for leaks, six failed

while all of the three new apparatus passed. The Wilcoxon

rank-sum tests showed that new units did not perform differently from deployed units in any performance measure.

All deployed and new units tested on the BMS reached

4% CO2 before the O2 supply was expended; five of the

deployed and two of the new units occurred before 60 min

(table 6).

Activation of the sodium chlorate candle, which provides an initial volume of oxygen, sometimes results in

visible white smoke emanating from the mouthpiece. This

occurred in the treadmill test, and the test subject did not

want to breathe the smoke. Instead, after the smoke

stopped, a manual start was performed consisting of exhaling into the mouthpiece eight times and then donning the

apparatus. The test subject reported feeling nauseated for

the first 10 min of wear and terminated the test at 72 min

after feeling light-headed. All measured stressors were

within acceptable ranges, although minimum inhaled CO2

levels were climbing and reached 2.1% by test termination.

It should also be noted that, because of large apparatus dead

space, average inhaled CO2 levels would be significantly

higher than this. The difference between minimum and

average inhaled CO2 levels with a 1.67-L tidal volume as

used in the BMS tests is approximately 2%.

OCENCO EBA 6.5

Ten apparatus were found to have been altered from

their original manufacturer's condition. The units had been

opened, their service life indicators changed to extend their

service lives, some components replaced, and then reassembled without applying new tamper seals. Some of these

units exhibited cracks in their cases, dents in their canisters,

had lithium hydroxide (LiOH) dust in their mouthpieces and

breathing bags and had very high breathing circuit leak

rates. Several apparatus were tested on the BMS before we

discovered that they had been altered; they performed

normally, however. The perpetrator of the unauthorized alterations was discovered and ordered by MSHA to stop.

Two of the thirty-eight deployed apparatus tested for

breathing circuit tightness passed the leak test; 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

performance measures, new units could not be distinguished

from deployed units.

Twenty-two deployed units tested on the BMS and one

on the treadmill reached average inhaled levels of 4% CO2

before the O2 supply was expended; none occurred before

60 min (table 7). No new units experienced this

phenomenon.

The large range of average inhaled O2 level test averages

is due to the difference in the apparatus O2 regulator flow

rates, which ranged in this phase from 1.51 to 2.62 L/min

ATPD (approximately 1.36 to 2.36 L/min STPD). The

O2 concentration in a breathing circuit will rise if the

O2 supply rate is higher than the O2 consumption rate.

Table 6.—MSA Portal-Pack CO2 breakthrough times,

minutes

Type of unit and

test method

CO2 breakthrough time

Test

duration

Maximum

CO2

Deployed: BMS . . 43 69 10

47 62 10

72 77 4.5

72 73 4.9

50 71 10

49 69 7.3

51 78 9.1

New: BMS . . . . . 49 71 11.5

54 74 15.8

61 66 4.6

CO2 breakthrough for BMS - 4% average inhaled; for treadmill -

4% minimum inhaled.

Table 7.—Ocenco EBA 6.5 CO2 breakthrough times, minutes

Type of unit and

test method

 CO2 breakthrough time

Test

duration

Maximum

CO2

Deployed: BMS . . . 102 103 4.2

106 114 5.7

105 105 4

111 111 4

96 97 4.3

104 108 5.1

102 103 4.4

94 94 4

97 99 4.2

92 107 7.1

107 113 5.3

93 103 6.7

92 102 7.2

94 115 8.3

94 106 7.7

88 104 9.3

102 103 4.2

99 113 5.8

91 107 5.9

87 105 6.2

97 110 5.5

94 105 8

Deployed: Human

 subject on treadmill . . 103 103 4

CO2 breakthrough for BMS - 4% average inhaled; for treadmill - 4%

minimum inhaled.
12

OCENCO M-20

Of the nine deployed units tested for leak tightness,

four passed; of the three new units, one passed. All except

one deployed BMS-tested apparatus, all of the new BMStested apparatus, and the one treadmill-tested apparatus

experienced average inhaled CO2 levels of 4% before exhaustion of the oxygen supply (table 8).

The Wilcoxon rank-sum tests revealed that the wet- and

dry-bulb temperatures of new units were statistically significantly higher than those of the deployed units. This is

not viewed as a problem.

The breathing bag and mouthpiece of one unit had

somewhat taken a set in their folded packing orientations,

but not to the extent that donning of the apparatus was

compromised.

Table 8.—Ocenco M-20 CO2 breakthrough times, minutes

Type of unit and

test method

CO2 breakthrough

time

Test

duration

Maximum

CO2

Deployed: BMS . . . . . . . . 14.5 17 6.6

13.5 17 6.7

14 18 6.9

15 18.5 6.2

15 18 5.3

15 18 5.7

15 17 4.8

16 16.5 5.8

Deployed: Human subject

 on treadmill . . . . . . . . . . 14 15 4.4

New: BMS . . . . . . . . . . . . 15.5 18 6.6

15.5 17 5.2

15 17 5.8

CO2 breakthrough for BMS - 4% average inhaled; for treadmill - 4%

minimum inhaled.

CONCLUSIONS

The results of this sixth-phase SCSR test study at PRL

suggest that the large majority of SCSRs that pass their inspection

criteria can be relied upon to provide a safe level of life support

capability to allow miners to escape safely during a mine

emergency. However, the mining environment seems to have

caused some performance degradation in the CSE SR-100 and the

MSA Portal-Pack. Several Portal-Packs were found to have KO2

dust in their mouthpieces. NIOSH-Morgantown and MSHA, after finding more instances of this problem, decided to decertify

the Portal-Pack. CO2 levels were found to be higher in deployed

CSE SR-100s than in new ones (table 3 and figure 7). No

statistically significant worsening in any other performance

category was detected in the SR-100 or any other apparatus. The

SR-100 has been belt-worn longer than any other SCSR. It may

be that this type of impact is in store for all belt-worn apparatus

and will become evident as other belt-worn apparatus have more

field time.

The smoke sometimes emitted from the chlorate candle of the

MSA Portal-Pack may suggest that the apparatus is malfunctioning and lead the user to abandon it. Since the apparatus

is no longer being used, the point is moot, but should be remembered by manufacturers in future design efforts.

ACKNOWLEDGMENTS

Without the cooperation of the coal mines and MSHA field offices, this study would not be possible. The following coal mines

and MSHA field offices participated in the sixth phase of this study:

Cooperating mine or MSHA office Assisting MSHA office Mining company Mine name

MSHA District 2:

 Rosebud Mining Co. . . . . . . . . . . . . Rosebud No. 3 . . . . . . . . . . . . . Kittanning, PA, Field Office.

 Rosebud Mining Co. . . . . . . . . . . . . Roaring Run . . . . . . . . . . . . . . . Kittanning, PA, Field Office.

 Dunkard Mining Co. . . . . . . . . . . . . . Dunkard Mine . . . . . . . . . . . . . . Waynesburg, PA, Field Office.

 Canterbury Coal Co. . . . . . . . . . . . . DiAnne Mine . . . . . . . . . . . . . . . Indiana, PA, Field Office.

 Consolidation Coal Co. . . . . . . . . . . Bailey Mine . . . . . . . . . . . . . . . . Washington, PA, Field Office.

 Consolidation Coal Co. . . . . . . . . . . Enlow Fork Mine . . . . . . . . . . . . Washington, PA, Field Office.

 MSHA . . . . . . . . . . . . . . . . . . . . . . . Johnstown, PA, Field Office . . . —

MSHA District 4:

 Elk Run Coal Co. . . . . . . . . . . . . . . . White Knight Mine . . . . . . . . . . Mt. Hope, WV, Field Office.

 Eastern Associated Coal Corp. . . . . Harris No. 1 . . . . . . . . . . . . . . . . Mt. Hope, WV, Field Office.

 Maple Meadow Mining Co. . . . . . . . Maple Meadow Mine . . . . . . . . . Mt. Hope, WV, Field Office.

 Mystic Energy, Inc. . . . . . . . . . . . . . Candice 2 Mine . . . . . . . . . . . . . Madison, WV, Field Office.

 RWJ Mining, Inc. . . . . . . . . . . . . . . . Mine No. 7 . . . . . . . . . . . . . . . . Princeton, WV, Field Office.

 DuPaul Resources, Inc. . . . . . . . . . . Mine No. 1 . . . . . . . . . . . . . . . . Pineville, WV, Field Office.

 Terry Eagle Coal Co. . . . . . . . . . . . . Bald Eagle No. 1 Mine . . . . . . . Summerville, WV, Field Office.

MSHA District 5:

 Crystal Bay Corp. . . . . . . . . . . . . . . . Mine No. 2 . . . . . . . . . . . . . . . . Richlands, VA, Field Office.

 Island Creek Coal Co. . . . . . . . . . . . Virginia Pocahontas No. 3 . . . . Richlands, VA, Field Office.

 Lebo Mining, Inc. . . . . . . . . . . . . . . . Mine No. 5 . . . . . . . . . . . . . . . . Norton, VA, Field Office.

MSHA District 9:

 Twentymile Coal Co. . . . . . . . . . . . . Foidel Creek Mine . . . . . . . . . . . Price, UT, Field Office.

MSHA District 11:

 U.S. Steel Mining Co. . . . . . . . . . . . Oak Grove Mine . . . . . . . . . . . . Hueytown, AL, Field Office.
13

REFERENCES

Hodgson, JL [1993]. Physiological costs and consequences of mine escape and

rescue. University Park, PA: The Pennsylvania State University. U.S. Bureau of

Mines contract Nos. J0145038 and J0345327.

Kyriazi N, Shubilla JP [1992]. Self-contained self-rescuer field evaluation:

results from 1982-90. Pittsburgh, PA: U.S. Department of the Interior, Bureau of

Mines, RI 9401.

Kyriazi N, Shubilla JP [1994]. Self-contained self-rescuer field evaluation:

fourth-phase results. Pittsburgh, PA: U.S. Department of the Interior, Bureau of

Mines, RI 9499.

Kyriazi N, Shubilla JP [1996]. Self-contained self-rescuer field

evaluation: fifth-phase results. Pittsburgh, PA: U.S. Department of Energy,

RI 9635.

Kyriazi N, Kovac JG, Shubilla JP, Duerr WH, Kravitz J [1986]. Selfcontained self-rescuer field evaluation: first-year results of 5-year study.

Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9051.
DHHS (NIOSH) Publication No. 98-

1998

To receive other information about occupational safety and

health problems, call

1-800-35-NIOSH (1-800-356-4674), or

visit the NIOSH Home Page on the World Wide Web at

http://www.cdc.gov/niosh