Evaluation of a novel fire-blocking gel 

to prevent and suppress mine fires

A.C. Smith

Team leader, Fire Prevention Team, Fires and Explosions Branch

National Institute for Occupational Safety and Health (NIOSH), Pittsburgh, PA

D.C. Fredley

President, Northwest Barricade LLC., Newport, WA

D. Lauriski

President, Safety Solutions Int. Inc., Parker, CO

E.D. Thimons

Chief, Ventilation and Toxic Substances Branch 

National Institute for Occupational Safety and Health (NIOSH), Pittsburgh, PA

Abstract

The National Institute for Occupational Safety and Health (NIOSH) and Northwest Barricade LLC 

(NWB) conducted a study to evaluate the effectiveness of a novel fire blocking gel for use in underground 

coal mines to extinguish or retard the growth of a coal fire. The gel agent was subjected to controlled 

laboratory testing to assess its ability to delay coal ignition. It was then evaluated to determine if manual 

fire hose application could be used to apply the agent to mine roofs and ribs to provide a safe egress 

for mine rescue teams from a fire area. The gel agent was also evaluated in a water sprinkler system to 

determine its potential for use in conveyor belt fire suppression systems. The agent was then tested in 

live-fire exercises to examine its effectiveness in retarding and extinguishing a deep-seated coal fire and 

wood fire. Lastly, the ability of a mine rescue team to quickly and safely apply the gel agent to a mine 

entry during a simulated mine fire exercise was determined.

Introduction

In 2006, tragedies at the Sago Mine, the Aracoma Alma 

Mine No. 1 and Darby Mine No. 1 led to sweeping federal 

legislation, including the MINER Act of 2006. As part of the 

MINER Act, the U.S.Congress provided funding in the form 

of an emergency supplemental appropriation to the U.S. National Institute for Occupational Safety and Health (NIOSH) 

Office of Mine Safety and Health Research (OMSHR). The 

OMSHR was charged with developing existing and new 

technologies related to oxygen supply, refuge chambers, 

rescue and response, including firefighting technologies and 

communications and tracking that could be applied to mining. 

In 2007, the OMSHR issued a broad agency announcement 

for development and demonstration of mine health and safety 

technology. A contract was awarded to Northwest Barricade 

LLC, in association with Barricade International Inc., and 

Safety Solutions International Inc. to evaluate the use of fire 

blocking agents to suppress coal mine fires.

The information provided in this paper is from research 

conducted under Centers for Disease Control (CDC), NIOSH 

contract #HHSD200200824618C, “Technical Solutions for 

Enhancements to Mine Safety Using Barricade II Fire Blocking 

Gel.” Northwest Barricade LLC, in association with Barricade 

International Inc. and Safety Solutions International Inc., 

completed the work between April 2008 and October 2008. 

CONSOL Energy Inc. provided assistance in the laboratory 

coal ignition testing and provided experienced mine rescue 

team members to participate in the testing at their Robinson 

Run Mine and the NIOSH Lake Lynn Fire Suppression Facility. The purpose of this contract was to conduct tests of this 

product only. There may be other firefighting products (gels, 

foams, etc.) available that might produce similar results using 

similar test methods.

Barricade II fire blocking gel description

Barricade II is a fire prevention, fire retardant and firefighting substance initially designed to protect residential and 

other structures from wildfires. The product is nontoxic and 

biodegradable, according to its Material Safety Data Sheet, 

using only a safe, superabsorbent polymer and food-grade 

components in the formulation. Since its initial development, 

Barricade II has been found to be equally effective in protecting 
structures and in extinguishing fires, including but not limited 

to those involving magnesium, gasoline and diesel fuel, wood, 

tires and trees.

Barricade II, when injected into water at very low percentages (2.0 to 3.0%), forms a gel coating that provides thermal 

protection to structures, vehicles, fuel tanks or any other object 

when exposed to a fire. It is specially formulated to adhere to 

vertical, horizontal and inverted surfaces, such as walls, glass, 

metal, fiberglass and wood. Barricade II produces a virtually 

instantaneous gel when mixed with water through a shear 

device, such as an eductor fire nozzle, eduction into a water 

stream or batch mixing. The gel/water stream from a nozzle is 

applied directly to the surface to be protected. The viscosity of 

the gel/water mixture can be controlled by changing the mix 

ratio of the gel in water at the eduction or mix point. Different concentrations and viscosities can be produced depending 

upon the particular fire retardant, suppressant or extinguishing 

application needs. For example, for application and adherence 

to horizontal, sloping or vertical surfaces, or to the underside 

of horizontal surfaces, the concentration will range from 2.0 to 

3.0%. A lower concentration of Barricade II in water results 

in a thinner coating that will flow around and under complex 

surfaces, such as trees, bushes and plants. This is particularly 

advantageous in enhancing the effectiveness of firebreaks and 

for aerial application during wildfire. For these applications, 

mix ratios range from 1.0 to 2.0%.

Barricade II is produced by dispersing a super-absorbent 

polymer in vegetable cooking oil with food-grade stabilizer and 

thickener. The dispersion is composed of a dry, cross-linked 

polymer of at least one hydrophilic monomer dispersed in 

vegetable oil. The polymer is a copolymer of acrylamide and 

acrylic acid derivatives (e.g., an acrylate salt). The polymer 

may also be a terpolymer of an acrylate salt, acrylamide and 

2-acrylamido-2-methylpropanesulfonic acid (AMPS) salt. 

The polymer particles resulting from the polymerization are 

generally ground to less than about 74 microns in size, usually with 70% of the particles being less than 37 microns in 

size. However, polymer particles having a size ranging from 

about 10 microns to about 200 microns may be used. A low 

hydrophile-lipophile balance (HLB) surfactant is used to aid 

in the dispersion of the dry polymer particles in the vegetable 

oil. A particularly suitable low HLB surfactant is sorbitan monooleate, used in chocolate production. A suspending agent, 

fumed silica, is used to provide stability and flowability to the 

dispersion. This allows the dispersion to be introduced to the 

water supply in a liquid form.

The gel is formed after the dispersion is added to the firefighting water. Gel formation generally occurs in about three 

seconds or less. The gel has a viscosity ranging from 100 cps 

to 50,000 cps. The polymer particles in Barricade II absorb 

significant quantities of water in relation to their size and 

weight. The protective gel consisting of water-laden polymer 

particles evaporates less quickly than plain water. After several 

hours or several days, the outermost layers of drying gel can 

be replenished by misting with water.

Experimental results

Laboratory coal ignition testing. Laboratory tests were 

conducted at the CONSOL Energy Inc. R&D test facility in 

South Park, PA to determine the effect of treating coal with the 

Barricade II gel on the time to evaporate water from the coal 

sample, delaying the eventual ignition of the coal. Also, the 

effect of the water-to-gel ratio on the time value was evaluated. Minus 60-mesh Pittsburgh seam coal was used in all of 

the laboratory ignition tests. The as-received moisture content 

of the coal ranged from 12-15%. Tests were conducted on 

coal samples treated with Barricade II gel in percentages by 

volume of 0.5, 1.0, 1.5, 2.0, 2.5 and 3% in water. Tests were 

also conducted on untreated coal and coal mixed with water 

as control samples. To make the coal/Barricade II samples, 

7.5 g of the coal and 7.5 g of Barricade II at the various water/

concentrate ratios were weighed by electronic scale and then 

hand mixed for several minutes until visually homogeneous. 

The coal/Barricade II test samples were mixed at the Barricade 

International laboratory in Hobe Sound, FL and sent to the 

CONSOL Energy Inc. laboratory in South Park, PA. 

The ignition tests were conducted on 1-g samples of the 

coal and coal/Barricade II mixtures in a LECO TGA 701 

ThermoGravimetric Analyzer (TGA). The TGA controls the 

temperature and rate of temperature increase of the furnace 

containing the coal sample by the rates programmed by the 

laboratory chemist. The temperature of the furnace was raised 

to 107° C and allowed to remain at that constant temperature 

until the weights of the crucible contents reached stability from 

moisture loss. The furnace temperature was then increased at 

a rate of 40° C/min until it reached 750° C and then held at that 

temperature until the sample was completely ashed.

The untreated coal sample and the coal/water mixture reached 

a constant weight, indicating complete drying of the samples, 

at 107° C in 33 minutes. The drying time for the Barricade IItreated samples increased with the amount of gel used, ranging 

from 50 minutes for the 0.5% mixture to 78 minutes for the 

3.0% mixture. The results show that the samples treated with 

Barricade II significantly slowed moisture loss compared to 

the coal-only and coal-water-only control samples. The longer 

time required for moisture loss in turn delayed coal ignition. 

This test demonstrates what is experienced in practice when the 

Barricade II concentrate-water mix is applied to combustible 

materials. The Barricade II protects the material from impinging fire by coating the material with enough water to delay or 

prevent combustion for periods of time directly proportional to 

the volumetric ratio of Barricade II to water. The furnace test 

also shows that Barricade II’s effectiveness as a fire retardant 

increases as the amount of concentrate increases. 

Manual applications of Barricade II gel on coal. Barricade II is used in aboveground applications as a fire retardant or fire stop to protect residential structures and other 

combustible materials. It is hypothesized that the application 

of the gel to the roof and ribs of a mine entry or conveyor belt 

could retard or stop a propagating coal or belt fire, providing 

valuable time for miners to fight the fire or escape, if necessary. However, since the product is specifically formulated for 

aboveground applications, tests are needed to determine if the 

gel will adhere to coal mine surfaces, particularly rock-dusted 

surfaces, to determine the optimum application methods and 

the durability and stability of the product when applied. Tests 

were conducted at CONSOL Energy’s Robinson Run Mine 

and in the NIOSH Bruceton Safety Research Coal Mine. The 

objectives of the tests were to determine appropriate manual 

application techniques to apply the product to the ribs, roof, 

floor and conveyor belt and the product’s adherence and stability when applied. Factors evaluated included the gel/water 

mixture ratio, ventilation, nozzle type and application method.

CONSOL Energy’s Robinson Run Mine test. The first 

test was conducted in a conveyor belt entry at the CONSOL 

Energy Inc. Robinson Run Mine in West Virginia. The measured 

air volume in the belt entry was 12.1 m3/s. The estimated air 

temperature was 13° C. The first application of Barricade II 
occurred in the belt entry through 30 m of standard 5-cm fire 

hose with a water pressure of 1,650 kPa. The nozzle used 

was a Gel Pro-30 manufactured by Cordova Inc., specifically 

designed for eduction of Barricade II gel (Fig. 1).

Figure 1 — Gel Pro-30 nozzle.

The nozzle is modified to educt and mix aqueous firefighting 

gel Class A and B foams or wetting agents. The variable ratio 

eductor allows three different mix settings (1%, 3% and 6%, 

depending upon the viscosity). The eductor is calibrated for 1.9 

L/s at 700 kPa and can operate in the pressure range of 500 to 

1,000 kPa. Eduction nozzles such as the Gel-Pro 30 work on 

the venturi principle with an attached vacuum chamber. There 

are two orifices that the gel concentrate moves through. There 

is an orifice in the body of the nozzle at the venturi and one 

in the vacuum chamber that also includes a spring valve to 

prevent potential back pressure from forcing water back into 

the gel concentrate container. These two orifices must be sized 

appropriately to allow for the maximum flow rate and pressure.

In the initial test, the Barricade II was educted from a 15-L 

bucket through 1.6-cm hose into the eduction nozzle. In general, the concentration of Barricade II desired for adherence 

to vertical and inverted surfaces is approximately 3%. In this 

case, due to the high pressure through the fire hose, 1,650 

kPa, water volumes flowing through the eductor nozzle were 

significantly higher than is normally seen with the standard 

application pressures of 700 kPa or less. It was determined 

from video footage of the Barricade II application that the 

concentration of Barricade II was between 1 and 2%. The total 

Barricade II concentrate used was 11 L. Assuming a 1.9 L/s 

flow rate through the Gel-Pro 30 nozzle, 625 L of water were 

mixed with 11 L of Barricade II. This is a concentration of 

1.8%, had the water pressure been 700 kPa. Because of the 

high pressures, however, it is reasonable to assume a lower 

concentration was applied during the test. As a result of the 

lower-than-expected concentration, the Barricade II/water 

solution from the nozzle did not have optimum adherence to 

the mine surfaces. 

After making some adjustments, the pressure was reduced 

to 1,170 kPa. While still exceeding the desired maximum 

pressure for optimum Barricade II application, and using the 

same nozzle, Barricade II was applied to the roof, rib and 

belting. In the area of the test, rock dust had been applied and 

was approximately 0.5 cm thick. Excellent adherence to the 

rock-dusted rib and roof was observed. In a few small places, 

the rock dust with applied Barricade II “sloughed” from the rib, 

due to the thickness of the applied gel. The belt entry ventilation 

had no effect on the application. Observations confirmed that, 

consistent with standard use and application methods, a wide 

spray pattern is better for effective and efficient application of 

the gel/water mix. The narrow spray pattern tended to strike 

the surface with too much force to allow the Barricade II to 

adhere effectively. The wide stream application allowed the 

miner applying the gel to better “lay” the gel onto the surfaces.

Based on the tests performed at CONSOL’s Robinson Run 

Mine, the following can be concluded about the adherence and 

use of Barricade II in an underground coal mine application:

• Barricade II, when applied at high water pressures (>1,000 

kPa ) has an adherence capability that is less effective 

than it would be at lower water pressures (< 1,000 kPa).

• Barricade II adheres effectively to the roof, rib, belting 

and to rock-dusted surfaces that are present in underground coal mines.

• The application of Barricade II is best when applied with 

a wide nozzle spray pattern and is less effective when 

the spray pattern is narrow.

• After the application of gel, even at the higher water 

pressures, hydration occurs and the gel coating expands 

in thickness and becomes more visible and prominent 

on mine and mine equipment surfaces.

Figure 2 — Roof and rib after gel application.

Bruceton Safety Research Coal Mine test. The next test 

was conducted in the NIOSH Safety Research Coal Mine at 

Bruceton, PA. The objective of this test was to apply the gel to 

a larger area in the mine, simulating the application by a mine 

rescue team to retard the propagation of a coal fire. Another 

objective of this test was to monitor the stability and duration 

of the gel. During a pretest visit, the area of application, water 

system and fire hose were inspected, temperature and humidity 

readings were taken and a test application was performed with a 

2 L/s Gel-Pro eduction nozzle, and a 1 L/s Quik Atak eduction 

nozzle. The pretest application was conducted by Barricade 

personnel on a rib in an area adjacent to that selected for the 

actual test. It was determined that the 2 L/s nozzle provided 

the best method of application for this test.

The test application was conducted by a CONSOL Energy 

Inc. mine rescue team. The team was given the option of using 

a 18-L container in a backpack or using the 18-L container to 

be carried behind the nozzle man by a hose man. The team decided to have the hose man carry the bucket and be responsible 

for renewing buckets as needed during the application. The 
ambient air temperature during the application was 17o C and 

the relative humidity was 70%. Airflow was not measured but 

was perceptible. The water was delivered at 700 kPa through 

a standard 4-cm fire hose attached to a 5-cm water line. The 

entry height was 1.8 m and the width varied from 4 to 5.5 m. 

The gel was applied to the roof and ribs of a 18-m-long section of the entry as the team advanced in the entry. During 

the advance, the hose man had to supply one additional 15-L 

bucket of Barricade II concentrate. The advance application 

took 5.2 min. Total spray time as determined from the video 

was 4.3 min. Bucket changeover took 52 s. The team examined 

the roof, ribs and face for application consistency and decided 

that no additional application was necessary. The amount of 

Barricade II concentrate used for the application was 21 L. 

Total water used through the 2 L/s nozzle for the 4.33-minute 

application was 488 L, yielding an average Barricade-II-towater percentage of approximately 4%. The total square feet 

of application to the roof, ribs and face was 147 m2. Figure 2 

shows the roof and rib after the application test.

The rescue team was very satisfied with the ease and speed 

of application. They were also favorably impressed with the 

uniform 0.6 cm thickness and adhesion of the application. 

The nozzle man stated that it only took a minute of application to understand the optimum spray pattern from the nozzle 

Figure 3 — Roof and rib 48 hours after gel application.

Figure 4 — Eductor in 1-1/2 in water line.

Figure 5 — Second water/Barricade II sprinkler flow test.

Figure 6 — Barricade II coating on top conveyor belt after 

sprinkler application test.

for maximum effectiveness of application. The rescue team 

members and Barricade personnel also observed the area of the 

entry that was treated during the pretest, five days earlier. The 

gel was still hydrated and would be effective in retarding a fire.

The team viewed the application area 24 and 48 hours 

after the test application. Although some slight slippage due 

to gravity was observed in some areas of the application, no 

significant visual difference was noted, as shown in Fig. 3, at 

48 hours. The mine foreman reported from an examination 

after eight days that the gel was still wet and still had some 

depth. In a subsequent examination 16 days after application, 

it was noted that the gel was drying along the ribs but still had 

texture and depth on the roof.

Sprinkler system application of Barricade II Gel on 

conveyor belting. Tests were conducted at the Lake Lynn 

Fire Suppression Facility (FSF) to evaluate the application of 

Barricade II through a typical mine sprinkler system installed 

along a belt drive and belting material. The sprinkler system 

at the FSF uses fusible link sprinkler heads rated for 68° C. 

The water supply system delivers water to the sprinkler heads 

through 4-cm branch lines tapped into a main 10-cm water 

line. Each sprinkler head delivers 3.8 L/s at 1,200 kPa. Each 

4-cm branch line services two sprinkler heads: a sprinkler head 

above the top belt and a sprinkler head between the top and 

bottom belt. The sprinkler system is designed and installed in 

accordance with Federal regulations for use in underground coal 

mines. To determine the adequacy of the water/gel mixture flow 
through the system, the piping was configured to isolate one 

of the branch water lines and the two corresponding sprinkler 

heads located above the top belt and between the top and bottom belt. The fusible links were removed from the sprinkler 

heads to allow for immediate flow upon water introduction. 

The Barricade II gel concentrate was introduced into the water 

flow using an eductor, shown in Fig. 4, rated at 7.5 L/s. Two 

tests were completed. In the first test, 3.8 L (1 gal) of Barricade 

II was allowed to enter the system when the water supply was 

turned on. The second test was timed and took 30 s to educt 

5.7 L of Barrricade II into the water flow. Figure 5 shows the 

Barricade II/water spray flowing from the top sprinkler head 

during the second test.

The results of the sprinkler system application of Barricade 

II gel on the conveyor belting, shown in Fig. 6 after the second 

flow test on the top belt surface, indicates that the introduction 

of Barricade II into a main water line and sprinkler system in a 

concentration that would both flow throughout the system and 

be in a concentration to be effective in firefighting is feasible. 

The gel coating on the belt surface showed uniform thickness 

and consistency, equivalent to a coating applied through the 

end of a fire hose.

Coal fire extinguishment tests. To determine the effectiveness of Barricade II in extinguishing a coal fire, two large-scale 

tests were conducted in the Lake Lynn FSF. In the first test, the 

coal fire was extinguished by NIOSH and Barricade personnel. 

In the second test, the extinguishment was by an experienced 

CONSOL mine rescue team.

Test 1. In the first test, a 30-cm-deep layer of minus 5-cm 

Pittsburgh seam coal was spread evenly in a steel mesh box, 

0.9-m-wide by 1.8-m-long, shown in Fig. 7. 

Figure 7 — Test 1 coal fire configuration.

The coalbed was 

raised approximately 23 cm from the floor to allow ventilation 

from all sides of the coalbed. Six thermocouples were placed 

through the side of the box extending to the center of the coal, 

15 cm from the bottom of the coal. A thermocouple was placed 

15 cm from the fire initiation point on the upstream side of 

the ventilating current and each subsequent thermocouple was 

spaced at 30-cm intervals. The fire was ignited by placing 

a methane burner at the upstream end of the coalbed. The 

methane burner was turned off at 90 min when the coalbed was 

able to sustain the fire. Ventilation in the FSF was maintained 

at 1.5 m/s. Fire temperature data from the thermocouples was 

recorded throughout the burn process.

The fire was allowed to burn for 23 hours. During that time, 

the fire propagated through the coalbed, so that the entire coalbed 

was on fire at time of extinguishment. Barricade II was educted 

into the fire hose at a 3.0% concentration at the hose nozzle. 

The gel concentrate was applied through the same eduction 

nozzle used in the in-mine application experiments. The person 

extinguishing the fire carried a 15-L supply of the Barricade 

II gel concentrate in a backpack system. After 23 seconds of 

application, the coal fire was suppressed and cooled to a point 

that re-ignition did not occur. Water vapor was readily visible, 

but coal smoke was significantly suppressed. The team member 

extinguishing the fire noted that yellow fumes were emitted 

during the suppression process, but there was no re-ignition of 

the fire. It was also noted by the team that, except for nozzle 

overspray, there was virtually no gel or water directly below 

the fire box. This indicates that the mixture was adhering to 

the coal. It was observed that Barricade II application also 

had an “encapsulating effect” on the coalbed, shown in Fig. 8.

Figure 8 — Coalbed after Barricade II/water mixture 

application.

Test 2. The second coal fire test was conducted to evaluate 

the use of the Barricade II gel concentrate applied by an actual 

mine rescue team. In this test, a 30-cm-deep layer of minus 

5-cm Pittsburgh seam coal was spread evenly in a 1.8-m-long 

by 0.9-m-wide solid steel trough. The fire was ignited with accelerant and wood pallets to obtain fast involvement. CONSOL 

Energy Inc. provided experienced mine rescue team members 

to participate in the testing at Lake Lynn. Figure 9 shows the 

coal fire just prior to extinguishment.

Figure 9 — Coal fire just prior to extinguishment by mine 

rescue team.

After a brief training exercise on the proper use of Barricade 

II application through end-of-hose eduction, the CONSOL team 
extinguished the fire. The CONSOL team used a standard 4 

cm fire hose with the Gel-Pro 30 eduction nozzle. The water 

pressure was 860 kPa and the Barricade II/water concentration used was 4%. The fire was extinguished in 70 seconds. A 

hand-held temperature probe was used immediately after the 

test and showed temperatures in the coalbed ranging from 75 

- 100° C. Figures 10 and 11 show the team approaching the 

coal fire and applying the gel/water mixture. 

Figure 10 — Mine rescue team approaching coal fire.

Figure 11 — Mine rescue team extinguishing the coal fire.

 Figure 12 shows 

the coal bed immediately after extinguishment.

Figure 12 — Coalbed just after extinguishment.

Coal fire retardant test. A primary use of Barricade II in 

aboveground applications is as a coating to protect combustibles 

from fire. For example, it is often applied to residential structures in the path of forest or wild fires. Tests were conducted to 

determine the retardant capability of Barricade II in a coal fire. 

A test was designed and conducted to compare coal treated with 

Barricade II to untreated coal exposed to fire. A 0.4-m-deep 

by 0.9-m-wide by 0.4-m-long layer of minus 5-cm Pittsburgh 

seam coal was placed in the upwind side of the 0.9-m-wide by 

1.8-m-long box wire-mesh box that was used in the first burn 

test. A 0.4-m-deep by 0.5-m-wide layer of coal was placed 

on one side of the remaining 1.5-m box and a similar layer of 

coal coated with a 3% mixture of Barricade II was placed on 

the other side of the box. The gel was applied by spreading 

the coal on the floor and applying the agent to the coal prior 

to being loaded into the test box. Thermocouples were placed 

in the coalbed, 0.2 m from the sides of the box in the middle 

of the coal layer at 0.3 m intervals beginning at 15 cm from 

the upwind side of the box. Figure 13 shows the treated and 

untreated coal in the box prior to ignition. 

Figure 13 — Coalbed prior to ignition.

 Figure 14 shows a 

schematic top view of the location of the thermocouples. 

Figure 14 — Top view of thermocouple locations in coalbed.

 The 

area shaded in blue is the coal treated with the 3% mixture of 

Barricade II.

A methane gas burner was placed at the upwind side of 

the box for 90 minutes to ignite the coal fire. Air velocity 

in the FSF throughout the test period averaged 2.3 m/s. The 
coal was allowed to burn to completion (approximately 130 

hours). Temperature readings were also taken with a handheld 

thermocouple probe near the in-place thermocouples at various 

times throughout the test. Figure 15 shows the temperatures 

in the coalbed 18 hours into test. 

Figure 15 — Temperatures, oC, in the coalbed at 18 hours.

 As can be seen in Fig. 15, 

the untreated side had higher temperatures than did the Barricade II treated side.

Figures 16 and 17 show the temperature-time traces of the 

thermocouples in the treated and untreated coal. 

Figure 16 — Temperature-time history of untreated coalbed

Figure 17 — Temperature-time history of treated coalbed.

 In Fig. 14, 

thermocouples T1 through T6 were in untreated coal. In Fig. 

15, thermocouple T7, although on the “treated” side, was placed 

in the first 0.4 m of untreated coal. Thermocouples T8 through 

T12 were in Barricade II-treated coal. The temperature-time 

plots show two effects of the gel treatment, an insulating effect 

and a time delay effect. The rate of temperature rise at the 

thermocouples in the treated side was actually greater. The 

untreated side shows a gradual increase in temperature, indicating that the fire front had a steady advance through the coalbed 

typical of coal fires. This indicates that there was an insulation 

effect that was gradually diminished due to encroaching fire 

cooking off the gel treatment, at which time the temperature 

rapidly increased. This insulation effect resulted in a delay 

in the treated coalbed reaching its maximum temperature 

compared to the untreated coal. For example, T3 begins to 

increase at 14:42 compared to T9 at 17:32 and T4 at 29:39 

compared to T10 at 30:42. What is also important to consider 

when analyzing the temperature/time data is that there was no 

confining membrane between the treated and untreated coalbeds. 

Therefore, the treated coal was being encroached by the fire 

both from the front and untreated coalbed side. 

Wood fire retardant and extinguishment demonstration. 

Tests were also completed using a wood pallet fire to dem-
onstrate both the retardant and extinguishment capabilities of 

Barricade II on a wood fire. Two stacks of six wood pallets 

each were placed over a pan that contained 7.5 L of a fuel oil/

gasoline accelerant. One stack was treated with Barricade II 

through a Gel-Pro 30 eduction nozzle at a 3% concentration 

prior to stacking. The accelerant was ignited and allowed to 

burn until the untreated stack was fully involved with fire. 

As shown in Fig. 18, the Barricade II-treated stack was fully 

protected from ignition, even though the accelerant flames 

penetrated throughout the stack.

Figure 18 — Wood pallet fire test.

When the untreated pallets were fully involved in fire, the 

CONSOL mine rescue team members quickly extinguished 

the fire using a hose with a 3% concentration of Barricade 

II, shown in Fig. 19. 

Figure 19 — CONSOL personnel extinguishing wood 

pallet fire.

 From start of extinguishment to the fire 

going out took 28 seconds.

Conclusions

This paper describes tests conducted to evaluate the effectiveness of the Barricade II fire blocking gel under the CDC 

NIOSH contract #HHSD200200824618C, “Technical Solutions 

for Enhancements to Mine Safety Using Barricade II Fire Blocking Gel.” The purpose of this contract was to conduct tests of 

this product only. There may be other fire-fighting products 

(gels, foams, etc.) available that might produce similar results 

using similar test methods.

Laboratory oven tests showed that the application of Barricade II to coal can delay its ignition by slowing moisture loss 

and subsequent temperature rise of the coal.

Barricade II can be applied quickly and effectively by a mine 

rescue team to large areas of ribs and roof in mine entries to 

potentially retard an advancing mine fire. The retarding action could provide an effective route of egress for firefighting 

personnel. Based on in-mine tests, the gel remained viable 

for several days.

Testing demonstrated that Barricade II can be used as a water 

replacement in a sprinkler suppression system similar to the 

type used in an underground coal mine belt drive installation.

Testing showed that the gel can retard a spreading coal fire 

when the coal is pretreated with the gel. Barricade II can also 

quickly and effectively extinguish and cool a coal fire.

Barricade II can retard the spread of a highly engaged wood 

pallet fire to an adjacent Barricade II-treated stack of wood 

pallets and quickly and effectively extinguish and cool a diesel 

fuel-initiated wood fire.

Barricade II can be an effective addition to mine firefighting 

techniques through end-of-hose eduction, as was demonstrated 

by mine rescue personnel. Application of Barricade II to the 

ribs and roof of an underground coal mine during a fire emergency can potentially protect firefighting and rescue personnel’s 

ingress and egress by retarding the spread of the fire.

Acknowledgments

We are grateful for the timely and expert assistance of 

NIOSH personnel at the Lake Lynn and Bruceton Mine facilities. These include Eric Weiss, Rick Thomas, John Soles, Jim 

Addis and Jon Jobko at Lake Lynn and Paul Stefko, Joe Sabo 

and Jack Teatino at Bruceton. In addition, we could not have 

completed this analysis without the expert assistance of John 

Bartlett, Barricade International Inc. and CONSOL Energy Inc., 

in particular their Mine Rescue Team members Larry Tenney, 

Craig Carpenter, Mark Koon, Captain, Robinson Run Mine 

Rescue Team; Cliff Ward, Captain, Shoemaker Mine Rescue 

Team; and George Joseph, Map Man, Bailey Mine Rescue 

Team; and laboratory personnel, Vince Conrad and Jacquie 

Fidler. Also present and assisting from CONSOL Energy Inc. 

was Bill Toliver, Manager of Fire Prevention, John Higgins, 

Manager, Northern West Virginia Operations, and Chris Clutter, videographer.