TESTING AND EVALUATION OF AN INFLATABLE TEMPORARY 

VENTILATION CONTROL DEVICE 

Michael A. Trevits, NIOSH, Pittsburgh, PA, 

Cliff McCartney, Strata Products (USA) Inc., Marietta, Georgia and 

H.J. (Bill) Roelofs, Minvent Solutions, Como, Western Australia 

Abstract 

The National Institute for Occupational Safety and 

Health (NIOSH) in partnership with Strata Products tested 

the sealing capability of Ventstop®TM as part of an 

ongoing mine fire control and suppression research 

program. Ventstop®TM is a multi-purpose, inflatable 

device that is produced by Minvent Solutions and is 

available world wide for use in the metal and nonmetal 

mining industry. Ventstop®TM is also used in the 

Australian coal industry as a temporary ventilation control 

device. The device can be quickly deployed, is reusable 

and can be placed in horizontal and vertical mine voids to 

control dust, fumes and smoke. Deployment, multi-day 

inflation and air leakage tests were conducted at the 

NIOSH Lake Lynn Laboratory to determine the capability 

and limitations of Ventstop®TM in a simulated coal mine 

setting. During the tests, Ventstop®TM was also subjected 

to low level forces of a nearby methane gas ignition. It is 

thought that Ventstop®TM could be used by the US coal 

mining industry to temporarily close an underground 

mine area in response to a fire or spontaneous combustion 

heating event, to temporarily redirect mine ventilation 

during longwall equipment moves or during stopping 

construction. This paper describes this inflatable 

temporary mine sealing technology and presents the 

results of the NIOSH tests. 

Disclaimer: The findings and conclusions in this report 

are those of the authors and do not necessarily represent 

the views of NIOSH. 

Introduction 

Subsequent to the underground coal mine tragedies 

early in 2006, at the Sago Mine, the Aracoma Alma Mine 

No. 1, and Darby Mine No. 1, sweeping changes were 

made to state and federal coal mining safety laws. With 

the promulgation of the Mine Improvement and New 

Emergency Response Act of 2006 (PL 109-236), also 

known as the MINER Act, the National Institute for 

Occupational Safety and Health (NIOSH) was charged to 

establish the Office of Mine Safety and Health (OMSH) 

to enhance the development of new mine safety 

technology and technological applications and to expedite 

the commercial availability and implementation of such 

technology for the mining industry. In addition, the 

OMSH was charged to conduct research, development, 

and testing of new technologies and equipment designed 

to enhance mine safety and health. To carry out such 

functions, the OMSH is actively awarding competitive 

grants to institutions and private entities to encourage the 

development and manufacture of mine safety equipment. 

The OMSH is also awarding contracts to educational 

institutions or private laboratories for the performance of 

product testing or related work with respect to new mine 

technology and equipment, and has established an 

interagency working group to share technology and 

technological research and developments that could be 

utilized to enhance mine safety and accident response. 

In June 2008, Strata Products entered into an 

agreement with NIOSH to test the sealing capability of a 

temporary ventilation control device called Ventstop®TM 

under the charter of the OMSH new technology 

evaluation program. NIOSH was also conducting a 

comprehensive program of research addressing 

metal/nonmetal and coal mine fire prevention, detection 

and suppression so this work fit well within the NIOSH 

program. It was thought that Ventstop® could be utilized 

by the US coal mining industry to temporarily close an 

underground mine area in response to a fire or 

spontaneous combustion heating event and to temporarily 
 

 

 

 

 

 

 

 

 

 

redirect mine ventilation during longwall equipment 

moves or during stopping construction. 

Strata Products in partnership with Minvent Solutions 

are industry leaders in designing, manufacturing and 

supplying safe, innovative and cost-effective and efficient 

mining products. Strata Products had previously decided 

to partner with Minvent Solutions who produces 

Ventstop®TM1

 and a host of other inflatable ventilation 

and protective structures for the metal and non-metal 

producing and processing segments of the mining 

industry globally. Minvent Solutions began in 1992 and 

had its start in the underground mining industry by 

designing and manufacturing an inflatable, reusable 

overhead protection system (Passline) for a 200 ft ore 

pass. Upon successful completion of that work, Minvent 

Solutions was then challenged to design a balloon that 

could be used as a plug/inflatable formwork base suitable 

for pouring concrete in a problematic ventilation shaft. 

From there the company designed inflatable devices for 

bulkheads, ventilation brattices and temporary walls. 

Since that time, the technology has evolved and now 

Minvent Solutions provides systems for the mining, 

milling and processing segments of the industry and has 

progressed into smelters and refineries. 

1

 Mention of a specific product or trade name does not 

imply endorsement by NIOSH. 

Ventstop®TM 

Ventstop®TM is a multi-purpose, inflatable device that 

is produced by Minvent Solutions and is available world 

wide for use in the metal and nonmetal mining industry 

(figure 1). Ventstop®TM is used as an emergency temporary 

ventilation control device, for controlling ventilation in 

breakthrough situations, to combat radiation dust, thermal 

heating return vent, blast fumes and fires. The device can 

be quickly deployed, is reusable and can be placed in 

horizontal and vertical mine voids. 

Figure 1. Photo of Ventstop.®TM 

Ventstop®TM was introduced into the Australian Coal 

Industry in 2005. These units were specifically designed 

to be placed in strategic areas around a mine for 

emergency deployment. The original device was a cubedshaped inflatable structure with square ends (new models 

for coal mining are cylindrical). The standard unit is 

constructed from a polyester scrim-based fabric with a 

double-sided polyvinyl chloride coating (Australia <30 

mega ohms NCB Specification 245) and meets the Mine 

Safety and Health Administration (MSHA) requirements 

for ventilation materials (MSHA Approval No. 07­

BA070011) [1-2]. 

In general, a Ventstop®TM unit will accommodate 

entry-width variations of 2 ft and height variations of 3 ft. 

The unit is typically sized 1 ft larger in diameter than the 

mine height to ensure the best fit because the surface of 

mine openings are typically rough and of non-continuous 

dimensions. Furthermore, if the diameter of the unit is 

larger than the mine height then mine roof and floor 

contact area is increased. There is a constraint on length 

of the Ventstop®TM unit relative to entry width. The unit 

should be no more than 1-to 2-ft longer than the entry 

width to minimize the possibility of wrinkling the fabric 

and thus increasing the potential for air to by pass the unit 

when inflated. Ventstop®TM is currently available in three 

standard sizes: 7 ft, 10 ft and 13 ft diameters by 18, 20 

and 22 ft lengths (these sizes are designed to fit a 

maximum 6, 9 and 12 ft high mine opening respectively). 

It should be noted that a unit can be custom built to any 

size and shape specification to accommodate any 

individual application. 

Ventstop®TM is completely portable and contains a 

single chamber that can be inflated from one fill port 

location by either mine compressed air or bottled 

compressed air with a venturi or a powered blower. The 

inflation pressure is very low, on the order of 0.25 to 

0.35 psi. The unit can be kept inflated for days using an 

available filtered pressure demand control system. This 

system provides a small gas flow to the Ventstop®TM unit 

to maintain appropriate pressure, and is capable of 

keeping a unit inflated even when it contains small holes 

or cuts. Holes or cuts in the unit can be temporarily 

repaired using a self-adhesive patch, and a permanent 

repair can be made by welding on fabric patch in fresh 

mine air. 

NIOSH Lake Lynn Experimental Mine 

The research was conducted at the NIOSH Lake 

Lynn Experimental Mine (LLEM), located approximately 

60 miles southeast of Pittsburgh, Pennsylvania. The 

LLEM is a world-class, highly-sophisticated underground 

facility where large-scale explosion trials, mine fire 

research and a myriad of other mine safety and health 
 

 

 

 

 

 

 

 

research programs are conducted. The underground 

workings are sized to match those of commercial mines, 

thus making them true, full-scale test galleries. Movable 

bulkheads permit the setup of single-entry, triple-entry, 

and longwall face configurations for experiments 

(figure 2) [3]. 

Figure 2. Layout map of the Lake Lynn
 

Experimental Mine. 

The air leakage and deployment tests were conducted 

in the first crosscut between the B and C-Drifts of the 

LLEM (figure 2). The crosscut measured 18.3 ft (wide) 

by 6.8 ft (high) by 40 ft (long). The mine floor sloped to 

the southwest at a 1.1% gradient. The test area was set up 

so the long axis of the Ventstop®TM structure could be 

installed perpendicular to the crosscut. The mine roof in 

this area was irregular and did not contain any roof bolts 

or steel protrusions. 

Ventilation for the mine is provided by a ventilation 

shaft with a fan located about 550 ft away in the E-Drift 

(figure 2). The fan speed is adjustable to 4 different 

settings and provides for a variety of test conditions. 

Figure 3 shows the flow rate for the fan for two different 

mine configurations for three of the fan speeds (note the 

C-Drift closed, D-Drift bulkhead door closed 

configuration was used in this study). 

Figure 3. Flow rate for the LLEM fan at 3 speed settings 

The test area was set-up so that the all of the air (and 

resulting pressure) from the fan would be directed at the 

Ventstop®TM unit. To minimize air leakage, the 

intersecting drift openings (B- and C-Drifts) were closedoff using brattice cloth affixed to a wooden frame. To 

permit differential pressure measurements, 1⁄4-in diameter 

tubing was attached to the mine roof across the opening 

spanned by the Ventstop®TM unit and extended through the 

nearby downstream brattice cloth and wooden frame 

structure. This location served as the evaluation point for 

the tests (figure 4). Air leakage rates were determined 

using a vane anemometer and the measurements were 

made at a hole that was cut into the brattice cloth (at the 

B-Drift intersection) the same diameter as the 

anemometer. Mathematical calculations were then made 

to determine the final air leakage rate using the 

anemometer and differential pressure measurements. 

Video cameras were mounted on both sides of the 

Ventstop®TM unit to document the tests. 

Figure 4. Layout map of the study area in the No. 1 

crosscut of the LLEM. 

Deployment Tests 

The Ventstop®TM unit used in this study was a 

prototype constructed of the fire-retardant and anti-static 

fabric. The unit measured 10 ft in diameter and was 20 ft 

long and weighed 150 lbs. The Ventstop®TM unit was 

installed by two persons several times in the mine 

opening to determine how long it would take to fully 

deploy the unit. The unit was inflated using mine air and 

a venturi. On average it took approximately 7.5 minutes 

to install the unit from the carry bag to full inflation in the 

mine opening (5.5 minutes to inflate the unit only) 

(figures 5-6). Deflation of the unit, folding and 
 

 

 

 

 

replacement into the carry bag took about 15 minutes 

(11 mnutes to deflate the unit only). Once the unit was 

installed in the mine opening, it was determined that 

91.5 ft2 of contact area (5 ft by 18.3 ft) was made at both 

the mine roof and floor areas with a total contact area of 

340 ft2

 including the roof, floor and side areas. 

The deployment tests were conducted with the mine 

fan turned off and thus in the absence of active mine 

ventilation air currents. When the fan was turned on and 

all of the air was directed through the crosscut, problems 

were experienced when trying to hold the unit in place to 

initiate inflation even at the lowest fan setting. Although 

the unit contained two hold down loops, it was not 

possible to securely fasten the unit to the mine opening 

because the loops were designed for maneuvering the 

prototype unit during inflation and were affixed to the 

outside of the unit rather than through the fabric and 

secured from the inside surface. When the test was 

repeated and the brattice was removed from the C-Drift 

opening (thus providing an alternative flow path for the 

air when the Ventsop®TM unit was deployed), the problem 

experienced earlier with inflating the unit did not occur 

(for the air leakage tests, the brattice was reinstalled 

across the C-Drift opening). 

The problem of installing the unit in high flow mine 

ventilation air can be overcome by setting a line of 

wooden posts (cribbing blocks or other supplemental 

mine roof support structures can also be used) across the 

width of the entry and inflating the unit against the posts. 

The use of nylon netting was also suggested by previous 

researchers to deploy other inflatable devices in active 

mine air [4]. To alleviate the installation problem in 

active mine air, the design of the unit has since been 

altered to include additional hold down loops that are 

attached from the inside and are intended for affixing it to 

a rib or roof bolts prior to inflation. 

Figure 5 – Carry bag for transporting the Ventstop®TM unit. 

Figure 6. Inflation sequence for the Ventstop®TM unit. 

During deployment, adjustments were made to 

position the unit correctly in the mine opening and to 

remove wrinkles in the fabric. These adjustments were 

made by holding the fabric (either at the hold down loop 

or by clutching the fabric) and moving it to the desired 

position. This task was relatively easy provided it was 

done before the unit was fully inflated. If a problem area 

(such as a wrinkle) was observed after the unit was fully 

inflated, the problem could be easily corrected by 

partially deflating the unit, making the adjustments in the 

fabric and re-inflating the unit. Figures 7 and 8 shows the 

unit fully inflated in mine opening. 

Figure 7. Fully deployed Ventstop®TM unit as 

viewed from the C-Drift side. 

Figure 8. Fully deployed Ventstop®TM unit as viewed from 

the B-Drift side. 
 

 

 

 

Air Leakage Tests 

A series of 4 air leakage tests were conducted to 

determine the sealing capability and limitations of the 

prototype Ventstop®TM unit. The test area was set up as 

described earlier and all of the air from the fan was 

directed towards the Ventstop®TM unit (refer to figure 4). 

A description of the tests, objectives and commentary 

about the tests are shown in Table 1. 

Table 1. Description of Air Leakage Tests. 

Air Procedure and Leakage Objective Comments Test No. 

Compare air 

leakage rates at Air leakage measurements 

1 two different made on two separate 

inflation days. 

pressures. 

Apply 

polyurethane 

(PUR) sealant Measurements made on and compare 2 same day after sealant had pre- to post- cured. sealant 

application air 

leakage rates. 

Pressure demand control 

system was used to ensure 

that unit would remain 

inflated. Pressure 

maintenance level for After PUR control system was set application, below the initial setting 3 compare air pressure. Measured air leakage rates leakage at start of test, after 24 hrs. after 24 hrs, then repressurized unit to 

previous day’s inflation 

pressure and measured air 

leakage. 

Inflated unit measured air 

leakage. Conducted 

nearby methane gas 

ignition. Unit set for 24 Observe effects hrs without the use of the of nearby 4 pressure demand control methane gas system. Measured air ignition on unit. leakage, then repressurized to previous 

day’s inflation pressure 

and measured air leakage. 

Figure 9 shows the results of Test No. 1. The 

objective of this test was to compare air leakage at two 

different inflation pressures that could be used in an 

actual underground mine setting. As shown in the figure, 

air leakage was decreased by about 25% at the higher 

inflation pressure. In all likelihood, the increased pressure 

forced the unit to fit more tightly across the irregular 

surface of the mine opening. 

Figure 9 Plot of air leakage during Test 1. 

Figure 10 shows the application of a PUR sealant to 

the upwind side of the Ventstop®TM unit as a supplemental 

means of minimizing mine air leakage. The PUR sealant 

was sprayed along the entire perimeter at the interface 

between the Ventstop®TM unit and the mine opening. The 

expanded thickness of the applied sealant was about 5 in 

and tapered in thickness to 1/8 in at a depth of about of 

18 in using the standard spray head provided with the 

PUR material. 

Figure 10. Application of PUR to the perimeter of the 

Ventstop®TM unit. 

Figure 11 shows the results of Test 2 in which preand post-PUR sealant application air leakage tests were 

conducted. As expected, a dramatic decrease in air 
 

leakage (85%) occurred subsequent to the application of 

the PUR sealant. Smoke tube testing prior to the PUR 

application showed that most of the air leakage was 

occurring near the mine roof and rib interfaces and these 

air leakage paths were mostly eliminated with the 

application of the sealant. 

 Figure 11. Plot of air leakage as observed during Test 2. 

Recently, there has been some concern about heat 

build-up in conventional mine seals constructed from 

PUR material. Though the intended use of the Ventstop®TM 

unit is for temporary ventilation control and the PUR 

material is a supplemental sealing material that is applied 

to one side of the perimeter of the unit (up to 5.5 in thick), 

it was decided to conduct a heat build-up test using a 

swatch of the Ventstop®TM fabric and the PUR sealant. In 

this test, a 24-in square piece of the Ventstop®TM material 

was affixed to a wooden frame. Attached to the frame 

were four wooden legs that positioned the frame 2 ft 

above the ground surface. Three thermocouples were used 

in the experiment: one measured ambient mine 

temperatures; one was positioned to measure heat buildup in the polyurethane mass and was located 1 in above 

the top surface of the fabric (in the center of the square); 

and the third one measured heat transfer through the 

Ventstop®TM material and was affixed to and touching the 

underside of the fabric (also in the center of the square). 

The temperature of the fabric surface was allowed to 

equilibrate to the ambient mine temperature for 4 days 

before the PUR sealant was applied. PUR sealant (the 

same type used in the air leakage tests) was then sprayed 

onto the top surface of the Ventstop®TM fabric to an 

expanded thickness of 5.5 in. The temperatures at all 

locations were recorded for 23 hrs and until they were at 

or near the ambient mine temperature. Figure 12 shows a 

photograph of the PUR material after it was cut apart to 

recover the thermocouple. 

Figure 12. Cutaway view of the PUR mass from

 heat build-up test. 

This figure shows that the PUR was applied correctly 

and the material cured evenly across the test surface. 

Figure 13 shows the temperature data for this test. It can 

be observed from the test results that the heat build-up 

rate was very fast and achieved a maximum temperature 

of 188oF (well below its auto-ignition temperature). Heat 

transfer to the underside of the fabric was much less and 

reached a maximum value of 83oF. 

Figure 13. Plot of temperature data for the PUR heat 

build-up test. 

Air leakage Test 3 involved a 24 hr inflation test with use 

of the pressure demand control system. This system was 

designed to maintain a set inflation pressure on the 

Ventstop®TM unit. An air leakage measurement was 

made at the beginning of the test (at 0.36 psi inflation 

pressure) after the PUR sealant was applied and 24 hrs 

later at the maintenance pressure of 0.22 psi. The unit 
 

 

 

was then inflated to 0.36 psi (the original inflation 

pressure) and another air leakage measurement was made. 

Figure 14 shows the results of Test 3. It is unknown 

how many times the pressure demand control system was 

used to re-pressurize the Ventstop®TM structure during 

the overnight test. When mine air leakage was measured 

(after 24 hrs), the unit actually leaked less air at the lower 

inflation pressure (0.22 psi). Furthermore, when the unit 

was re-pressurized to the previous day’s pressure setting 

(0.36 psi), the unit leaked less air than the day before. It 

is thought that the re-pressurizing cycle (or cycles) caused 

the Ventstop®TM structure to seat more tightly in the mine 

opening and thus leak less air as observed in the test. It 

should also be kept in mind that these air leakage rates are 

very low, approaching the limits of the measuring method 

and may not be completely accurate. 

Figure 14. Plot of air leakage as observed during Test 3. 

Air leakage Test 4 was carried out while a methane 

gas ignition test was being conducted at a different part of 

the mine. The Ventstop®TM unit was approximately 

1,250 ft from the A-drift ignition zone. The pressure 

pulse from the ignition traveled through the A-Drift, 

crossed into the B- and C-Drifts and then was applied to 

the Ventstop®TM unit at two slightly different times due to 

travel distance. Pressure transducers were placed on both 

sides of the Ventstop®TM unit to capture the magnitude of 

the pressure pulse. Based on the B-Drift pressure data, 

the Ventstop®TM unit was subjected to an initial peak 

positive pressure (after some oscillations) of about 0.08 

psi, followed by a peak negative pressure of about 0.25 

psi, then another peak positive of about 0.15 psi followed 

by a peak negative of about 0.1 psi; this oscillation 

continued until the end of the 12 second data acquisition 

time. Based on the C-Drift pressure data, the Ventstop®TM 

unit was subjected to an initial peak positive pressure of 

about 0.45 psi, followed by a peak negative pressure of 

about 0.65 psi, then another peak positive of about 

0.5 psi; at that point, the 12 seconds of acquisition time 

ended. The peak sweeping pressure value appears to be 

in the 0.5-0.6 psi range [5]. Upon visual inspection, the 

Ventstop®TM unit appeared to be intact. Figure 15 shows 

the results of air leakage tests conducted before the 

ignition, 1 day after the ignition (the unit had lost 0.12 

psi) and then when it was re-inflated to the pre-ignition 

conditions. The data on the plot suggests that no 

significant change in air leakage occurred as a result of 

the ignition. 

Figure 15. Plot of air leakage as observed during Test 4. 

Comparison of Ventstop Air Leakage 

Rates with Stoppings 

®TM

In a study conducted by the US Bureau of Mines 

(USBM), five different stopping construction techniques 

were evaluated and air leakage tests were performed [6]. 

The stoppings studied included conventional stoppings 

that were built by dry-stacking hollow-core concrete 

blocks and troweling mortar on one stopping face; quickbuild stoppings that were built in the same manner as 

conventional stoppings except brushed-on glass-fiber 

enhanced mortar (modified mortar) was substituted for 

troweling; universal stoppings that were built of dry 

stacked hollow-core blocks, had a footer, keyed ribs, 

sealed roof and one face sealed with one coat of modified 

mortar; high-pressure stoppings that were built of hollowcore wet-laid concrete blocks, had a footer, keyed ribs, a 

sealed roof, two brushed-on coats of modified mortar on 

one face and one coat of brushed-on modified-mortar on 

the other face; and hybrid stoppings that were built the 

same way as high-pressure stoppings, except that solidcore blocks were used instead of hollow-core blocks. 

Figure 16 shows a comparison of the leakage rates for 

Ventstop®TM at 0.22-, 0.36-psi and 0.36-psi inflation 

pressure with PUR applied from this study with the other 

types of newly constructed stoppings from the USBM 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

study. Also for comparative purposes, the air leakage 

rates were converted to cubic feet per minute per hundred 

square feet of stopping area per inch water gauge pressure 

differential [6]. As can be observed in the figure, the air 

leakage rates for the Ventstop®TM unit were among the 

lowest leakage rates observed. Also, the leakage rate for 

the Ventstop®TM unit with PUR applied was the lowest rate 

measured. 

Figure 16. Air leakage for various newly constructed 

stoppings and Ventstop®TM. 

Summary and Conclusions 

Ventstop®TM is a multi-purpose, inflatable device 

produced by Minvent Solutions and is available world 

wide for use in the metal and nonmetal mining industry. 

Ventstop®TM is used as an emergency seal (temporary 

ventilation control device), controlling ventilation in 

breakthrough situations, radiation dust, thermal heating 

return vent, blast fumes, fires, pass plugs and shaft sealing 

system. The device can be quickly deployed, is reusable 

and can be placed in horizontal and vertical mine voids. 

Ventstop®TM was introduced into the Australian Coal 

Industry in 2005. 

A series of tests, conducted at the NIOSH LLEM, 

showed that Ventstop®TM could be quickly deployed by 

two persons in approximately 7.5 minutes (to install the 

unit from the carry bag to full inflation in the mine 

opening and 5.5 minutes to inflate the unit only). 

Deflation of the unit, folding and replacement into the 

carry bag took about 15 minutes (11 minutes to deflate the 

unit only). The tests noted a difficulty when attempting 

to install the unit in high flow mine ventilation air that can 

be resolved with additional more robust hold down loops 

(used in the newest design) or propping the unit during 

inflation against a series of posts, cribbing blocks or other 

supplemental roof support structure. Air leakage testing 

showed that the unit could provide an effective temporary 

mine seal that could be further enhanced through the 

application of PUR sealant. Inflation of the unit for 

extended periods of time (24 hrs or greater) is possible 

through the use of a pressure demand control system. In 

these tests, mine ventilation air leakage rates were 

between 55 and 175 ft3

/min depending on inflation 

pressure without the use of PUR sealant. When PUR 

sealant was applied to the unit, air leakage rates were 

substantially reduced by 85%. 

The Ventstop®TM unit was also subjected to the 

oscillating pressure pulses from a methane gas ignition. 

Though the ignition zone was approximately 1250 ft away 

and the resulting pressure pulse degraded as it traveled 

through a series of drift openings to the Ventstop®TM unit, 

it successfully withstood a maximum peak positive 

pressure pulse of 0.5 psi and maximum peak negative 

pressure pulse of 0.65 psi and a peak sweeping pressure 

value in the 0.5 to 0.6 psi range. Pre-and post-explosion 

tests show that the air leakage past the Ventstop®TM unit 

was not affected by the forces of the pressure pulses. 

Comparison of air leakage rates for Ventstop®TM at 

0.22-, 0.36-psi and 0.36-psi inflation pressure with PUR 

applied from this study with the several types of newly 

constructed stoppings from a previous USBM study 

showed the air leakage rates for the Ventstop®TM unit were 

among the lowest rates observed. Also, the leakage rate 

for the Ventstop®TM unit with PUR applied was the lowest 

rate measured. 

Ventstop®TM unit appears to be a promising 

technology for use as a temporary ventilation control 

device in US coal mines. The Ventstop® unit could be 

utilized by the US coal mining industry to temporarily 

close an underground mine area in response to a fire or 

spontaneous combustion heating event and to temporarily 

redirect mine ventilation during longwall equipment 

moves or during stopping construction. 

Acknowledgments 

The authors would like to Vito Virgili, Strata Safety, 

LLC, Larry Profitt, Strata Mine Services, Frank A. 

Karnack, Donald D. Seller, James D. Addis and Eric S. 

Weiss, NIOSH and the support staff at the LLL, for their 

professionalism, dedication, and assistance in the conduct 

of the field work needed to complete this study. We 

would also like to recognize Thomas A. Gray, Tetra Tech, 

Charles D. Campbell and Mark Schroeder, MSHA for 

their expertise in providing the technical review of this 

paper. 

References 

1.	 National Coal Board (NCB), 1985. NCB 

Specification No. 245: Fire and electrical resistance 

properties of supported and unsupported sheeting, 
issued by the National Coal Board of the United 

Kingdom. 

2.	 Code of Federal Regulations (CFR), 2008. Title 30, 

Part 7, Subpart B (2008). 

3.	 National Institute for Occupational Safety and Health 

(NIOSH), 1999. "Lake Lynn Laboratory (flyer)," 

Pittsburgh, PA: U.S. Department of Health and 

Human Services, Public Health Service, Centers for 

Disease Control and Prevention, National Institute for 

Occupational Safety and Health, DHHS Publication 

No. 99-149, 1 p. 

4. Weiss, E.S., R.S. Conti, E.M. Bazala and RW Pro, 

1996. Inflatable devices for use in combating mine 

fires, U.S. Bureau of Mines Report of Investigation 

9614, 18 p. 

5.	 Weiss, E.S., 2008. Senior Mining Engineer, 

Pittsburgh Research Laboratory, NIOSH Personal 

Communication, November 4. 

6.	 Timko, R.J. and E.D. Thimons, 1983. New 

techniques for reducing stopping leakage. U.S. 

Bureau of Mines Information Circular 8949, 15 p.