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IMBSIR 81-2326

Investigation of Solar Collector

Fire Incident

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Center for Fire Research

National Engineering Laboratory

Washington, D.C. 20234

August 1981

Prepared for: Department of Energy

Office of Solar Applications for Buildings

Washington, DC 20585

NATIONAL aUHJEAO Or STANDAKUfl UBBABT

NBSIR 81-2326

INVESTIGATION OF SOLAR COLLECTOR

FIRE INCIDENT

OCT 14

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William D. Walton

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Center of Fire Research

National Engineering Laboratory

Washington, D.C. 20234

August 1981

Prepared for: Department of Energy

Office of Solar Applications for Buildings

Washington, DC 20585

1981

1-2 2

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
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TABLE OF CONTENTS

Page

List of Figures iv

Abstract 1

1. INTRODUCTION 1

2. DESCRIPTION OF THE SITE 2

3. DESCRIPTION OF THE COLLECTOR AND SOLAR ENERGY SYSTEM .... 3

4. DESCRIPTION OF THE FIRE INCIDENT 5

5. EVENTS FOLLOWING THE FIRE 6

6. EXAMINATION OF COLLECTORS 7

7. CAUSE OF THE FIRE 8

8. SOLAR SIMULATOR TEST RESULTS 12

9. RESULTS OF 30 DAY STAGNATION TEST 14

10. EXAMINATION OF CODES AND STANDARDS 15

11. SUMMARY AND CONCLUSIONS 18

12. RECOMMENDATIONS 19

13. SUMMARY OF RECOMMENDATIONS 24

14. REFERENCES 25

iii
LIST OF FIGURES

Page

Figure 1. Site Plan . 27

Figure 2. House on lot 6 28

Figure 3. House on lot 22 28

Figure 4. House on lot 24 29

Figure 5. House on lot 33 . 29

Figure 6. Collector numbers 30

Figure 7. Collector section 31

Figure 8. Roof section 31

Figure 9. Collector involved in the fire - view of plywood back 32

Figure 10. Collector involved in the fire - view of interior

side of plywood 32

Figure 11. Collector 3, lot 33 33

Figure 12. Collector typical of lesser degradation 33

Figure 13. Collector typical of more severe degradation .... 34

Figure 14. Close up view of collector with severe degradation . 34

Figure 15. Back of collector with severe degradation 35

Figure 16. Simulator solar irradiance profile 36

Figure 17. Location of thermocouples in collector 37

Figure 18. Temperature distribution in collector mounted on

test frame 38

Figure 19. Temperature distribution in collector mounted on insulated roof deck. 39

Figure 20. Collector after 30 day stagnation exposure 40

Figure 21. Collector exposure conditions 41

Figure 22. Isothermal weight loss of polyurethane foam 42

iv
INVESTIGATION OF SOLAR COLLECTOR FIRE INCIDENT

William D. Walton

Center for Fire Research

National Bureau of Standards

Washington, DC 20234

Abstract

In May 1980, a fire involving a solar collector

occurred in Boulder, Colorado in an unoccupied single

family dwelling. Damage due to the fire was limited

to a single solar collector and adjacent roofing and

framing materials. Collectors of the same model on three other dwellings at the site showed signs of

degratation which may have led to similar fires.

The collector, installation, conditions leading to

the fire, and events following the fire are described.

The most likely point of ignition has been identified

as the plywood collector backing. Results of a 30-day

stagnation test and solar simulator testing are discussed. Recommendations to prevent future occurrences

of this type of fire are presented.

Key Words: building fires, fire safety, ignition,

self-heating, solar collector fires, solar collectors,

spontaneous ignition.

1. INTRODUCTION

In May 1980, a fire involving a solar energy collector occurred in

Boulder, Colorado in an unoccupied single family dwelling. This house

was part of a Federal residential solar heating and cooling demonstration

program. Damage due to the fire was limited to a single solar collector

1
and adjacent roofing and framing materials. An investigation revealed

that the solar collector itself was the only possible source of heat for

ignition. In addition, collectors of the same model on three other dwellings at the site were found to be in various stages of degradation which

may have led to similar fires. In July 1980, the Department of Energy

(DOE) Office of Solar Applications for Buildings requested the Center

for Fire Research of the National Bureau of Standards to review the

factors leading to ignition and to provide recommendations as to how

similar events may be prevented in the future. This preliminary report

primarily addresses the conditions found at the Boulder site. Additional

analysis and testing is necessary to define whether or not a fire risk

is likely to exist with other types of installations. The information

presented in this report concerning the fire incident was compiled from

interviews and an examination of the fire scene conducted by the author

in July 1980. This task was accomplished under interagency agreement

EA 77-A-01-6010.

2. DESCRIPTION OF THE SITE

Four houses utilizing identical solar collectors from the same manufacturer are located in a housing development in Boulder, Colorado. The

houses are of new (1979-1980) construction, each of a different design,

all located within approximately one block of each other. Figure 1

shows the layout of the site. The houses on which the collectors were

mounted are located on lots 6, 22, 24, and 33. Figures 2-5 show the

location of the collectors on the houses on lots 6, 22, 24, and 33,

respectively, as of early July 1980. (Note: the glazing on the

collectors was painted white after the fire to reduce solar heat gain.)

Since that time, all of the original collectors have been replaced with

collectors of a different design. All collectors face due south and it

can be seen from the figures that the houses on lots 6 and 24 each have

9 collectors and the houses on lots 22 and 33 have 10 collectors each.

The house on lot 33 was the site of the fire and the 10 collectors on

the house were mounted in two rows of 5. The collectors had been removed

and the fire damage to the roof repaired prior to the photograph.

2
Figure 6 shows collector numbers and arrangements on each house. The

collector numbers will be used for identification purposes in this

report.

The collectors were installed on the houses on lots 6, 22, and 24

sometime in early summer, 1979, and on lot 33 in the late summer. The

exact date of installation is not available. The houses on lots 6, 24,

and 33 were not yet occupied at the time of the fire, although all were

substantially complete. The house on lot 22 was occupied in early March

and the house on lot 6 became occupied in June subsequent to the fire.

Boulder, Colorado, is at an elevation of approximately 5400 ft

(1646 m) and receives approximately the median average annual solar

radiation in the United States based on land area. Collection of solar

irradiance data as a function of time has only recently begun so that a comparison of actual exposure conditions for this site with other locations can only be made in a general way.

3. DESCRIPTION OF THE COLLECTOR AND SOLAR ENERGY SYSTEM

The collector is of the flat plate type with overall dimensions of

approximately 36 inches (91 cm) wide by 94 inches (239 cm) long by 3-1/2

inches (8.9 cm) thick. The glazing consists of two sheets of tempered

glass separated by an air space and the absorber is pressure-bonded

copper with a black chrome selective surface. The insulation directly

behind the absorber plate consists of approximately 1-5/8 inches (4.4 cm)

of factory-applied spray-in-place urethane foam. The back of the

collector is 3/8-inch (0.95-cm) exterior grade plywood; the framing is

clear heart redwood. A cross section of the collector is shown in

figure 7.

The manufacturer of the collector has stated that the frame and the

plywood back are assembled and then the urethane foam is sprayed on the

plywood prior to the absorber and glazing being set in place. This process

appears to cause a natural adhesion between the plywood back and the foam

3
insulation.

The collectors on all of the houses are mounted in direct contact

with the roof which has a slope of 6 in 12 (26.6 degrees). All of the

houses except the one on lot 24 have M 90-lb." rolled roofing with a granular surface between the collector backing and the 1/2-inch (1.3-cm)

CDX plywood roof deck. The house on lot 24 has "30-lb." roofing felt

between the collector backing and the roof deck. The reason for this

difference appears to have been determined by the onsite availability of

materials

Because each house is of a different design, the roof construction

and collector mounting varies with each house. All of the collectors on the houses on lots 6 and 33 are mounted on roof decks insulated with 6

inches (15 cm) of kraft paper-faced glass fiber insulation between 2x8

inch joists which are 24 inches (61 cm) on center. A layer of gypsum

board underneath forms the interior finish of a cathedral type ceiling.

A cross section of this assembly is shown in figure 8. Collectors 1 and

6 on lot 22 appear to be mounted over uninsulated roof decks and the

remaining collectors on this house over the same type of insulated deck

shown in figure 8. All collectors on the house on lot 24 appear to be

mounted on an uninsulated roof deck.

The solar energy system in which the collectors are installed is an active liquid type designed to provide domestic hot water and space

heating. A liquid storage tank is used to satisfy demand when solar

energy cannot be collected. The heat transfer fluid is water and freeze

protection is provided by a "drain down" design. In this type of system

when solar energy cannot be collected such as at night or when the

temperature of the storage liquid has reached 180°F (82°C), the system

shuts down and the water drains from the collectors. In an unoccupied

house during periods with warm outdoor temperatures the primary demand

would be in making up the heat losses in the storage tank. This would

normally be accomplished by one or more relatively brief periods of

operation during a typical sunny day. Although the system operating

4
history for each house is not known, it is likely that the collectors

experienced nonoperating or stagnation conditions during a significant

portion of the time between their installation and the fire. Stagnation

conditions result in the highest collector absorber plate temperatures.

4. DESCRIPTION OF THE FIRE INCIDENT

The solar energy system in the house on lot 33 probably was not

placed in operation until several weeks before the fire. Approximately

one week prior to the fire the system was shut down due to a pump failure.

The contractor ordered a replacement pump and the system remained in a nonoperating condition until the time of the fire. The first indication

of a fire occurred when a neighbor noticed smoke coming from the collectors

and notified the Fire Department at 7:19 p.m. on May 29, 1980. The

weather on this day was clear with little wind, although there had been

some rain during the weeks preceding the fire. Upon arrival, the Fire

Department found smoke coming from around the solar collectors and from

the ceiling inside the house in the area of the collectors. The gypsum

board ceiling and insulation were removed from the inside and the fire was extinguished with a small hose line. When a representative of the

building contractor arrived on the scene, the collectors were raised

slightly and water was run underneath to ensure that the fire was out.

The Fire Department then left the scene, although their investigation

continued

At no time did the firefighters observe open flaming, but there was

considerable smoke in the ceiling area. The fire damage was limited to

a single collector (number 4 on lot 33), the roof, and one joist space

directly below the collector. After extinguishment, the absorber plate

of the collector could be seen by looking through the hole in the ceiling

from inside the house. Figures 9 and 10 show the collector involved in

the fire after it had been removed from the house. In figure 9 the view

is of the back of the collector with what is believed to be the upper

end of the collector as it was mounted, at the bottom of the picture.

Figure 10 shows the same collector with the plywood back turned over so

5
that the remaining urethane foam on the inside of the collector is

visible. These and all other pictures in the report were taken approximately 1-1/2 months after the fire. The roof deck under the collector

had a hole approximately the same size as the hole in the collector, and

there was charred material on the underside of the deck around the hole

and approximately 2 inches down on the adjacent roof joists.

5. EVENTS FOLLOWING THE FIRE

A few days after the fire the building contractor removed the

collector involved in the fire and the two adjacent collectors in order

to repair the roof. Collector number 3, which is shown in figure 11

with a hole in the back, was most likely not involved in the fire. The

hole was created by one of the workmen when the collector was removed

from the house. This collector shows substantial thermal degradation,

apparently from solar heating. Collector number 5 showed only moderate

degradation.

Approximately two weeks after the fire, a meeting was held at the

site with the contractor, designer, collector manufacturer, and fire

department staff in attendance. At this time the collectors which had

been removed from the house on lot 33 were examined. In addition,

collectors from the houses on lots 6 and 24 were removed and examined.

All of these showed considerable degradation of the urethane foam insulation. At this time it was decided to shut down all of the systems and

paint the glazing of the collectors to prevent further heating of the

insulation. A few days later it was decided that all collectors on the

site would be removed and a newer model collector installed in their

place. At this time an agent of the government agency sponsoring the

demonstration program asked the contractor to send two of the collectors

not involved in the fire from the house on lot 33 to the Boeing Company

for testing in their solar simulator.

6
In early July, 1980, all remaining collectors were removed from the

houses and opened for inspection with representatives of both the National

Bureau of Standards and the manufacturer present. Following this inspection, the manufacturer installed new collectors of a different design on all of the houses at the site.

6. EXAMINATION OF COLLECTORS

Examination of the collectors at the site revealed that in all the

collectors the urethane foam had thermally degraded to some extent.

Figure 12 shows a collector which is typical of those with the least

amount of urethane foam degradation found at the site. In this picture,

the plywood back with the foam attached is on the right and the remainder

of the collector with absorber plate visible is on the left. The end of

the collector which had been mounted towards the peak of the roof is at

the top of the picture. It can be seen from the small piece of foam

sitting on the upper left of the absorber plate that the blackening of

the foam had not progressed through to the plywood. Although the foam

had lost some of its original thickness and some cracking occurred, it

remained substantially intact.

Figure 13 shows a collector which was typical of those at the site

with more severe degradation. The collector in the photograph is in the

same orientation as the collector in figure 12. In this case, the foam

sitting on the absorber has darkened all the way through and some areas

of the foam are at approximately one-half the original thickness. In

addition, large cracks have formed throughout the foam layer. Close

examination reveals a darkening of the inside of the plywood backing

approximately 3 feet (0.9 m) down from the upper end of the collector.

Figure 14 shows a close-up of the upper two feet (0.6 m) of the

foam and plywood backing from the inside of a severely degraded collector.

The urethane foam which remains has been reduced to a layer approximately

1/4 inch (0.6 cm) thick. The plywood backing has blackened considerably

and begun to crack.

7
Severely degraded collectors also show degradation on the outside

of the plywood backing. Figure 15 shows the back center of a collector

between one and two feet from the end which was toward the roof peak

when mounted. Cracking and a slight darkening of the wood is visible in

this case.

No attempt has been made to rank the collectors in terms of their

relative degrees of degradation although the following general observations have been made. The collectors from the house on lot 33 showed

only moderate degradation with the exception of the collector involved

in the fire and the one adjacent to it. The collectors from lot 22 as a group showed more degradation than any of the other houses. In virtually

all of these the plywood backing had blackened to some extent. The

collectors from lot 24 showed a moderate degree of degradation with the

plywood beginning to darken on a few of them. In general, the collectors

from the house on lot 6 showed the least degradation but several did

have plywood which had darkened.

Taking the site as a whole there was no obvious pattern explaining

why some collectors had degraded more than others. There seems to have

been a slight tendency for those collectors over insulated roofs to show

more degradation but some of the collectors with the least degradation

were over insulated roofs. It is interesting to note that the house

with the most consistent severe degree of degradation had been occupied

the longest. However, the extent and duration of operation in the

stagnation condition for each house is not known.

7. CAUSE OF THE FIRE

Early in the investigation the Fire Department ruled out all

possible sources of heat for ignition with the exception of the collector

itself. There are no electrical wires or devices near the collector

involved in the fire. The closest heat producing appliance was a chimney

located three feet away from the collector and there was no fire damage

between the collector and the chimney.

8
The area of fire origin was most likely in the area of the hole

through the collector backing and the roof. From an examination of the

other collectors at the site the most probable material which first

ignited has been identified as the plywood collector back.

There is no question that the foam in all of the collectors was

degrading. The plywood backing showed signs of blackening or conversion

into charcoal only in areas where the urethane foam layer had become

very thin or where large cracks had opened exposing the plywood. As the

plywood is heated for long periods at moderate temperatures, charcoal is

formed which is susceptible to self-heating or smoldering. Self-heating

occurs when the heat generated by reactions within a combustible mass is

generated faster than it can be dissipated. The result may be that

glowing combustion or smoldering begins in the wood. Porous charcoal

containing a large surface area is subject to rapid oxidation and self

heating.

There are a number of articles in the literature [1 - 4]\ which

describe the behavior of wood exposed to moderately elevated temperatures.

Because the wood degrades over a long period of time and there are a large number of possible exposure conditions, wood types, and material

geometries, experiments on ignition of wood after prolonged heating are

difficult to conduct and the results vary. Experimental work and fire

investigations indicate that cyclic periods of heating and cooling, the

relative humidity of the air, the moisture content of the wood, the

oxygen supply, the type of wood, and the material thickness may all be

factors in determining the length and severity of exposure required for

ignition [5].

Although the data are varied, the following paragraphs from an American Plywood Association Report provide a reasonable summary of the

available data [6],

9
The thermal degradation and ignition point of wood and

plywood may be generalized by the following:

a) 230 to 302 F (110 C to 150 C) : The wood will char

slowly over time with the formation of charcoal.

If the heat is not dissipated there is some possibility of spontaneous combustion:

Examples of the thermal degradation of maple blocks

are:

1) 1050 days at 225 F (107 C) : 10% loss in weight

and slight discoloration.

2) 1235 days at 248 F (120 C) : 30% weight loss and

a chocolate color.

3) 320 days at 284 F (140 C) : 60% weight loss and

charcoal appearance.

b) 302 to 392 F (150 to 200 C) : Charring takes place at

a somewhat greater rate. If the heat source is close

to the wood, the surface temperature may be higher than

the temperature of the surrounding air due to radiant

heating. Gases released at these temperatures are not

readily ignited by an outside flame source. A greater

chance for spontaneous combustion is present if the heat

is not dissipated.

In tests, after 165 days at 302 F (150 C) maple blocks

showed a 60% weight loss, and the samples had the

appearance of charcoal.

c) 392 to 536 F (200 to 280 C) : The formation of

charcoal takes place at a rapid rate. Spontaneous

combustion is probable.

d) 536 F (280 C) and greater: Spontaneous combustion

will occur in a short period of time.

Because of the slow burning nature of a smoldering fire, it is

impossible to determine how long the fire smoldered before detection.

It is possible that it started one or more days before discovery. It

is not known therefore whether the fire started during a period of peak

solar radiation and what other factors may have been involved.

10
While it appears to be unlikely there are potentially several other

materials in which self heating could have occurred within the collector

assembly. Polyurethane foam has been known to self heat especially when

freshly made and stacked in large piles [7], There is very little information available on the temperatures at which rigid polyurethane foam

degrades when heated for extended periods of time. This is due in part

to the fact that its composition and properties vary widely. The evidence

in this case indicates that the polyurethane was not providing substantial

heat since the foam in the collectors not involved in the fire were

blackened from the absorber side and the plywood blackened only when

directly exposed to the absorber or when the foam layer was very thin.

The urethane foam may have contributed to the fire when ignited by the

glowing plywood. The fact that a considerable amount of the foam

remained along the sides of the collector in which the fire originated

as shown in figure 10 tends to support these conclusions.

Roofing papers and felts have been known to heat spontaneously,

although usually when in rolls [7]. In the case of the solar collector

there would have had to be substantial degradation of the foam insulation

and the wood before the roofing would have been heated to relatively

high temperatures. Examination of the other collectors showed that the

foam insulation and the wood did not have sufficient time to degrade to

that degree. There was no evidence that roofing materials on the other

houses were affected. The roof on the house involved in the fire was

replaced before this investigation was started. The roofing material

probably did contribute to the fire once it started.

In summary, the most probable fire scenario is that high absorber

plate temperature caused the polyurethane foam to degrade. The insulated

roof beneath the collector substantially reduced the heat loss resulting

in the plywood collector back being exposed to high temperatures. The

plywood decomposed, ultimately resulting in self heating which led to

ignition. The smoldering fire then consumed part of the back of the

collector and the adjacent roof deck before being extinguished by the

Fire Department.

11
8. SOLAR SIMULATOR TEST RESULTS

Two collectors from the house in which the fire occurred were

shipped to the Boeing Company for testing in their solar simulator.

Although the exact mounting location of the collectors is not known, it

has been determined that these collectors were from the group numbered

6 to 10 on lot 33. One of the two collectors was instrumented with

thermocouples and subjected to two seven-hour simulator exposure tests.

In the first test, the collector was mounted on a test frame with the

back exposed to free air. In the second test, the collector was mounted

directly on an insulated roof deck which was similar to the one on the

house in which the fire occurred. The test roof deck consisted of "30-

lb." felt (as opposed to the "90-lb." rolled roofing on the house on lot

33) over 1/2-inch (1 . 3-cm) plywood mounted on a 2 x 6 inch framing 24

inches (61 cm) on center, with 6 inches (15 cm) of glass fiber insulation

between the framing. The ceiling side of the simulated deck was covered

with 1/2-inch (1 . 3-cm) plywood.

Both configurations were tested at a tilt angle of 60 degrees with

the radiation normal to the collector surface. The radiation was provided

from xenon arc lamps with spectral filters [8]. The solar irradiance

profile is shown in figure 16 and the ambient temperature was a constant

85°F (29°C). This profile was selected to represent a typical good

solar day.

Thermocouples were placed at three locations in the collector, each

of them along the center line, as shown in figure 17. The first was 24

inches (61 cm) from the top end of the collector, the second in the

center, and the third 12 inches (30 cm) from the bottom end. At each of

these locations a 3-inch (7.6-cm) diameter core was removed from the

back of the collectors and thermocouples placed on the absorber, 1/2

inch (1.3 cm) into the foam from the absorber, 1 inch (2.5 cm) into the

foam from the absorber, and at the foam and plywood backing interface.

The core was then replaced and a fifth thermocouple placed on the back

side of the plywood backing.

12
The test results show some variation in temperature between the

three locations within the collector probably as a result of the condition

of the insulation and the mounting of the thermocouples. The temperature

profiles at the center of the collector are presented as typical of

those at the three locations. Figure 18 shows temperature profiles for

the collectors with no deck and figure 19 shows the profile for the

collectors mounted over the simulated insulated roof deck.

« The results show that the temperatures on the absorber plate and in

the foam increased by approximately 40 deg F (22 deg C) in the collector

mounted over the insulated roof deck. The greatest change was observed

in the peak plywood temperatures which increased by over 115°F (64°C).

For the collector with the back exposed to the air, the peak temperature

at the plywood/foam interface was 177°F (81°C) and on the back side of

the plywood the peak temperature was 141°F (61°C). In this case the

plywood temperatures seemed to respond quickly to changes in the

absorber plate temperature. The collector mounted over the simulated

insulated roof deck had a peak temperature at the plywood/foam interface

of 292°F (144°C) and 282°F (139°C) on the back side of the plywood. In

addition, the temperatures did not reach equilibrium during the one hour periods of constant exposure but continued to rise until the exposure

was t ermina t ed

Although the collector tested had been exposed at the site for a period of time under unknown conditions and the thermal properties of

the foam are unknown, some general conclusions can be drawn from the

test results. Collectors of this model would experience higher plate

and foam insulation temperatures when mounted directly on an insulated

roof deck as compared to those with the backs exposed to air. The

temperatures in the plywood backing can be expected to be significantly

higher when the collector is mounted on an insulated roof deck. The

results do not indicate temperatures that would be reached in the plywood

when the foam had completely deteriorated. In addition, the temperatures

obtained in a collector mounted on an uninsulated roof deck cannot be

accurately determined from those results except to say they would fall

13
between the two cases tested.

9. RESULTS OF 30 DAY STAGNATION TEST

A collector of the same model as that involved in the fire was

previously subjected to a 30-day stagnation test as a part of a DOE

collector testing program [9], In this test the thermal performance

of the collector is measured and then the collector is exposed to the

sun in the nonoperating mode for 30 days during which minimum prescribed

exposure conditions must be met. If the collector is intended for use in

non-drain down systems, it is filled with water with the inlet sealed and

the outlet set at the manufacturer's operating pressure, in this case

88 psi (6.06 x 10

5

Pa). If the liquid has not boiled out of the collector

after two days, the collector is drained. At the end of the 30 day

exposure, the thermal efficiency is measured again and compared to the

results of the first tests.

The results of the test conducted for DOE and similar tests conducted

for the manufacturer show, within the accuracy of the measurement, no degradation of thermal performance at the end of 30 days. The collector

in the DOE testing was later opened for inspection, which is not a normal part of the testing procedure. The foam insulation in this

collector had degraded to a lesser extent, but in similar fashion to

those from the site of the fire. Figure 20 shows the inside of the

collector which was mounted on a test rack with the back exposed to the

air during the tests. Figure 21 summarizes the conditions to which the

collector was exposed. The minimum daily solar radiation required by

2 2

the test procedure is 1500 BTU/ft /day (4725 Whr/m /day).

The results indicate that even though there is no measurable change

in thermal performance of the collector over the 30-day stagnation test

period, significant material degradation may actually be taking place.

14
10. EXAMINATION OF CODES AND STANDARDS

Several current or proposed performance criteria and standards have

been examined for sections dealing with the long term exposure of

materials subjected to higher than ambient temperature. The relevant

section in the HUD- Intermediate Minimum Property Standards Supplement

,

Solar Heating and Domestic Hot Water Systems [10] published by HUD is

essentially the same as that found in the Interim Performance Criteria

for Solar Heating and Cooling Systems in Residential Buildings [11]

and in the Interim Performance Criteria for Solar Heating and Cooling

Systems in Commercial Buildings [12],

Section S-600-6.4 from the HUD Solar Supplement [10] is as follows:

System Component Clearances

Combustible solids adjacent to solar equipment or an integral

part of a solar component shall not be exposed to elevated

temperatures which may cause ignition.

Commentary : Heating of cellulosic materials as well

as other combustible materials over an extended period

of time may result in the material reaching and surpassing

its auto-ignition temperature. The most commonly accepted

ignition temperature of wood is 392 F. However, studies

have indicated that wood may ignite when exposed to a temperature of 212 F for prolonged periods of time. The

ignition temperature of plastics may be above or below

those of cellulosic materials. Clearances for HVAC

equipment, ducting and piping are discussed in NFPA

No. 89M. Where applicable, clearances specified by

a nationally recognized testing laboratory may be used.

This section prohibits the use of materials which may result in

ignition. It does not, however, specifically indicate how to determine

if material will ignite when exposed to a given temperature for a long

period of time.

15
The requirements found in the Recommended Requirements to Code

Officials for Solar Heating, Cooling, and Hot Water Systems prepared for

DOE [13] are more specific. The scope paragraph covering the section

pertaining to clearances and the section itself are as follows:

B-101.1 Scope

The provisions of this section shall apply to the design,

construction, installation, alteration, materials, location,

repair and removal of solar systems and accessories connected,

attached, or adjacent to a building or structure. The provisions of this section relate to solar energy systems and

component requirements similar to those provided in the Building

Code.

B-102.3 Clearances

a. Combustible materials shall not be exposed to components

having operating temperatures that can cause ignition.

Clearances to combustible materials specified in the

component listing and marking shall be maintained.

b. Clearance between combustible materials and unlisted

components shall be maintained in accordance with the

following:

Installation Clearances

Sustained Design Surface

Temperature

200°F or less

200°F to 250°F

250°F to 500°F

Over 500°F

Required Clearance

(inches)

0

1

6

Section 102.3a applies

This section could be interpreted as meaning that rigid urethane

foam and wood would have to be mounted 6 inches away from a 400°F

(204°C) absorber plate or the component must be listed by a nationally

recognized testing laboratory.

The only known effort by a nationally recognized testing laboratory

to develop a comprehensive collector safety standard is a draft document

published by Underwriters Laboratories Inc. (UL) [14], Although this

draft standard contains a number of tests, only the "Temperature Test"

relates to the problem under discussion. For this test, thermocouples

16
are placed in selected locations throughout the collector so that the

temperature of the materials in the collector can be determined. If the

collector is intended for stand-off mounting, it is mounted on a test

frame with the back of the collector open to the air. If the collector

is intended for direct mounting, it is mounted on a platform of 1-inch

nominal wood boards or plywood 3/4 inch (1.9 cm) thick. The collector

is tested full of liquid with a relief valve set at the manufacturer's

recommended pressure. The collector is preheated so that temperatures

as determined by the thermocouples are at least two-thirds of the maximum

which will be obtained during the test. The collector is then exposed

2 2

to a solar radiation level of 300 BTU/hr/ft (945 W/m ) for two hours.

The maximum temperature of the materials in the collector shall not

exceed those specified in a table in the UL document. The table contains

a considerable number of materials but the ones of interest here are

wood and polyurethane foam insulation. The maximum permissible temperature for wood is 194°F (90°C) and for polyurethane is 327°F (164°C)

In summary, it is the intent of Minimum Property Standards [10] and

the solar criteria documents [11,12] that the installation of a solar

energy system shall not result in materials being exposed to elevated

temperatures sufficient to cause ignition. The draft UL safety standard

[14] limits temperature of urethane foam insulation to 327°F (164°C)

Simulator testing under conditions somewhat more severe than those

specified in the safety standard with the collector mounted on an insulated roof resulted in urethane foam temperatures in excess of 370°F

(188°C). The proposed building code document requires a clearance of 6

inches (15.2 cm) between combustible materials and unlisted components

with surface temperatures of 250 to 500°F (121 to 260°C). Neither the

proposed building code document nor the draft UL safety standard was

generally available at the time the collector was installed and neither

has been adopted for use in any jurisdictions.

17
11. SUMMARY AND CONCLUSIONS

A fire involving a solar collector in Boulder, Colorado, was

investigated. The collector was flat plate construction consisting of

double tempered glass glazing, a selective surface absorber, a 1-5/8

inch (4.5 cm) thick layer of polyurethane foamed in place behind the

absorber, and a 3/ 8- inch (0.95-cm) plywood back. The collector was

mounted directly on an insulated roof. The heat transfer fluid used was

water and the system was designed to drain down when not in operation.

The collector had been installed in late summer 1979 on the house which

was unoccupied and under construction. Although the operating history

of the solar system is not known, the system was probably not operating

most of the time since installation. Test results in a solar simulator

indicate the absorber plate could have reached temperatures in excess

of 400°F (204°C). The temperature reached in the collector caused the

polyurethane foam to degrade exposing the plywood to direct heat transfer

from the absorber. This is the most probable mechanism for causing the

plywood to char and created the potential for smoldering ignition.

Degraded polyurethane foam and charred plywood were observed in collectors

of the same model on other houses near the scene of the fire. The most

likely point of ignition was the plywood back of the collector. The

smoldering fire consumed the collector back and adjacent roof sheathing

and charred the roof joists. The fire was readily extinguished by the

Fire Department. An examination of the sections of solar codes, standards,

and criteria pertaining to this problem indicates the intent to prevent

the ignition of solar collectors. The codes and standards currently in

use do not provide a method of testing to insure that collectors meet

the intent.

The manufacturer of the collector involved in the fire states that

there are some 3,000 of these collectors installed in the United States,

of which less than 1% are mounted directly on roofs. Based on these

estimates, there are probably 300 to 900 installations with possibly 12

installations having collectors mounted directly on the roof. Because of

18
the distribution system for these collectors, a single list of all

installations is not available at this time. The collector manufacturer

has stated only rack mounting of the collector is recommended.

The evidence indicates that when this model collector is mounted

directly on the roof and subjected to conditions similar to those at the

Boulder site, a potential fire risk exists. The fact that a substantial

number of collectors at the Boulder site showed severe degradation

indicates that the problem was not a single defective collector.

Although collectors mounted on racks were not examined after a period of

actual use, the same model collector showed early signs of the same

degradation after a 30-day no-flow test. The question of whether

collectors at other sites will become involved in a fire can not be

answered definitively. It is likely that the urethane foam in collectors

at some or all installations has blackened and may have degraded. Even

if the plywood has begun to turn to charcoal, the conditions required

for smoldering ignition may never occur but the possibility cannot be

ruled out. An important question remaining unanswered is the condition

of collectors at other sites. In particular, how does a different

mounting configuration and different set of operating conditions affect

the materials in the collector? The effect of drain down operation on collector material temperatures has not been studied. Although the

degradation effects are cumulative, it is impossible to state definitively at this time whether or not a collector in a particular system

will ignite.

1 2 . RECOMMENDATIONS

The recommendations have been grouped into three areas: first,

actions which should be taken concerning collectors of the same model as the one involved in the fire which are currently installed on buildings;

second, means of determining if there are collectors on the market with

a similar potential for the occurrence of a fire; finally, actions which

can be taken to develop adequate codes and standards which will prevent

the occurrence of this type of incident.

19
It is recommended that a carefully selected sample of collectors

from various installations be examined to determine the condition of

combustible materials within the collectors. This sample should contain

specimens with various mounting configurations (including direct-on

roof), solar system characteristics, and climatic exposures. The

results of this study would provide significant insight into the magnitude of a potential fire risk. There is probably no way that an individual system owner can easily determine if a collector presents a risk of

fire occurring other than by opening and examining each collector. If

the system performance began to drop this would be an indication of

possible insulation degradation. A performance drop of this type could

only be determined after considerable analysis of a fully instrumented

system at a carefully monitored site. A collector mounted on an insulated roof may show very little performance change with the degradation of the collector insulation. The one technique that can be used as an indication of severe degradation is an examination of the back of the

collector for cracking. In most systems, however, the back of the

collector is not visible and there is no guarantee that this method will

always be effective.

Further solar simulation tests should be conducted to examine the

effects of collector mounting and insulation. As the insulation in the

collector is degraded the plywood backing is exposed to increased

temperatures and at the same time the insulating ability of the back

side of the collector decreases. Further analysis is necessary before a complete test program can be developed but this study has indicated

several tests which should be conducted. It is recommended that a collector of the same model as that involved in the fire, but with the

urethane foam insulation removed, be subjected to solar simulator

testing. One simulator test should be conducted with the collector

mounted on a test frame and a second test with the collector mounted on

a simulated insulated roof deck. For each of these tests the collector

should be instrumented with thermocouples located on the absorber plate,

at locations through the plywood backing of the collector and on the

20
back and sides of the collector. The irradiance profile should be the

same as the one shown in figure 16. These results, combined with the

observations taken at selected collector installations, would further

quantify the conditions under which a potential fire risk may exist.

Additional testing may be necessary to investigate the effects of partial

insulation degradation and collector edge heat loss.

A more immediate course of action may be necessary because of the

time required to select and examine additional collectors of the same

model as that involved in the fire. Serious consideration should be

given to issuing a bulletin describing the problem to owners of

collectors of the same model as that involved in the fire. Owners of

collectors mounted directly on the roof should be given priority in this

notification. In addition, it is recommended that a bulletin of a more

general nature be issued for the attention of collector manufacturers.

The wording of such a bulletin might be as follows:

Flat plate solar collectors under stagnation conditions can have absorber plate temperatures over 400°F (204°C) in the case

of double glazed, selective surface collectors and about 300°F

(149°C) in the case of single glazed, flat black collectors.

After some period of time at these temperatures, degradation of

plastic foam insulation, wood, and other combustible materials

may occur within the collector. The degradation can lead to

self ignition of these materials in some cases. The temperature

of materials in collectors mounted directly on a roof (particularly an insulated roof) will generally be higher than the

temperature in collectors mounted on spacers or standoffs.

One method available at present which may indicate a potential

problem is a collector tear-down and materials examination at

the end of a 30-day stagnation test. Materials which show

signs of degradation should be tested further to insure their

ability to withstand long term exposure to collector stagnation

temperatures

Modifications can be made to the collector or the collector installation to reduce the fire risk. The objectives of such modifications

would be, first, to prevent a fire originating in a collector from

spreading to the building on which it is mounted and to prevent heat

from the collector from igniting materials within the building and,

second, to prevent damage to the collector from either heat or fire.

21
The evaluation of modifications requires design considerations and

testing which is beyond the scope of this report.

While other collectors on the market may present the same potential

for fire risk, it should be noted that the design of the collector in

which the fire occurred is somewhat unique. The collector was designed

for high efficiency and thus was double glass glazed, tightly sealed,

had a selective surface absorber plate, and had urethane foam against

the absorber plate. These factors result in plate temperatures higher

than a number of other collectors on the market. A limited number of

other collectors with foam plastic insulation were visually examined in

the DOE collector testing program after 30 days of stagnation. The

only degradation noted was a slight color change in the foam. However,

the 30 day stagnation was conducted with collectors on racks and not on insulated roof decks. This may or may not indicate a tendency for these

collectors to degrade over long time periods but seems to indicate less

of a potential hazard at least in the short term.

Therefore, it is recommended that a study of currently available

collectors be undertaken to determine the short term hazard potential.

Based on manufacturers' literature and existing knowledge of collector

design, an engineering analysis should be made to assess the potential

for a fire to develop in or adjacent to the collector under various

mounting conditions. Testing could then be conducted on those collectors

thought to be a fire risk to confirm the results. If a collector is

found to present a definite hazard, a program to remedy the hazard would

have to be initiated.

The only known testing to examine the possible ignition of materials

within a collector was conducted on rack mounted wood construction air

type collectors at the Forest Products Laboratory [15]. The conclusion

stated in that paper is that stagnation temperatures could result in

smoldering ignition if maintained continuously for long periods of time

even though no visible signs of char were noted in the collectors tested

after one year of continuous stagnation.

22
To provide the consumer with solar collectors and solar energy

systems which are acceptably safe requires adequate building codes and

product safety standards. An effort to develop these codes and standards

has been underway for some time. Events such as the one under investigation indicate that more emphasis is required in developing and implementing these codes and standards. At this time, the major focus should

be directed towards developing and implementing a collector safety

standard. The draft UL safety standard is the most promising document

of this type and its development is continuing. Current exploratory

testing funded by DOE in cooperation with NBS is providing useful information on several areas covered by this standard. There is however, no known work currently underway specifically relating to the UL "Temperature

Test" which addresses the problem at hand.

The "Temperature Test" has two different aspects which are of

interest. First is the determination of temperature of materials in the

collector. Second is the evaluation of whether the materials can withstand long term exposure to those temperatures without degrading.

Although the standard addresses both of these issues, a number of

questions remain. It appears that the exposure conditions specified are

less than the maximum which can be obtained at many sites. The mounting

conditions specified may not be comparable to those of collectors mounted

directly on insulated roofs. In addition, there is no indication that a factor of safety has been included to accomodate uncertainties in the

measurements. Therefore, it is recommended that a developmental and

exploratory testing program be undertaken to examine the temperature

measurement portion of the "Temperature Test".

The second aspect of the "Temperature Test" of interest here is the

determination of the maximum temperature to which a material can be

exposed for extended periods of time. The literature generally agrees

that wood should not be exposed to temperatures greater than approximately 212°F (100°C) for extended periods of time. The draft UL Collectors

Safety Standard recommends a maximum temperature of 194°F (90°C) which

23
would generally be considered safe. The maximum permissible temperature

for polyurethane from insulation is given in the standard as 327°F (164°C).

Unpublished test results from the Boeing Company shown in figure 22

indicate that the polyurethane tested experienced approximately a 20%

weight loss when exposed to 350°F (177°C) for 72 hours. The urethane

tested had noticeably darkened after the exposure. These results indicate

that 327°F (164°C) is not a safe maximum permissible temperature for

urethane. This example is an indication of the inadequacy of the current

knowledge on exposure of materials like urethane to elevated temperatures.

This is further complicated by the fact that urethane foam describes a family of materials with varying properties. Therefore, it is recommended

that research be conducted with an emphasis on developing a test method

by which the effect of long term exposure of materials at elevated

temperatures can be determined.

13. SUMMARY OF RECOMMENDATIONS

The recommendations can be summarized as follows:

1. Concerning the collector involved in the fire:

A. Consideration should be given to issuing a bulletin

describing the problem to owners of collectors of the

same model as that involved in the fire.

B. A selected sample of collectors of the same model as that involved in the fire, from various installations,

should be examined to determine the magnitude of a potential fire risk. This study would be used as a basis for further recommendation.

C. Simulator testing should be conducted on collectors

with the urethane foam insulation removed.

2. Concerning other collectors currently on the market:

A. Consideration should be given to issuing a bulletin

to the industry describing the potential fire hazard.

B. Collectors should be opened at the end of the 30-day

stagnation test and examined for signs of material

degradation. If combustible materials have degraded

further testing should be conducted.

24
C. An engineering study of collectors on the market

should be conducted to determine if potential exists

for a similar incident. Testing should be conducted

on those collectors which show the potential.

3. Concerning codes and standards:

A. A program should be initiated to develop a standard

method for determining the maximum temperatures to

which materials will be subjected in a collector.

B. A test method should be developed to determine the

maximum temperature to which a material can safely

be exposed for extended periods to time.

14 . REFERENCES

[1] Schaffer, E.L., Smoldering Initiation in Cellulosics Under

Prolonged Low-Level Heating, Fire Technology, Vol. 16, No. 1,

pp. 22-28, (Feb. 1980).

[2] Forest Products Laboratory, Ignition and Charring of Wood, Forest

Products Laboratory Report 1464 (1958, reviewed and reaffirmed in

1963).

[3] MacLean, J.D., Rate of Disintegration of Wood Under Different

Heating Conditions, American Wood-Preservers Association, Vol. 47,

pp. 155-169, (1951).

[4] McGuire, J.H., Limiting Safe Surface Temperature of Combustible

Materials, Fire Technology, Vol. 5, No. 3, pp. 237-241

(August 1969).

[5] Matson, A.F., Dufour, R.E., and Breen, J.F., Part II Survey of

Available Information on Ignition of Wood Exposed to Moderately

Elevated Temperatures. Performance of Type B Gas Vents for GasFired Appliances, Bulletin of Research No. 51, Underwriters

Laboratories Inc., pp. 269-300, (May 1959).

[6] O'Halloran, M.R., Plywood in Hostile Environments; Physical Proper

ties and Applications, American Plywood Association Report 132,

pp. 8-9, (Dec. 1975).

[7] Materials Subject to Spontaneous Heating, Fire Protection Handbook

Fourteenth Edition, pp. 3-206 - 3-209, NFPA, Boston, Mass.,

(Jan. 1976).

25
[8] Streed, E. , Waksman, D. , Dawson, A. and Lunde, A., Comparison of

Solar Simulator and Outdoor ASHRE Standard 93 Thermal Performance

Tests, Proceedings 1980 International Solar Energy Society Meeting,

Denver, Colorado (June 1980).

[9] Waksman, D. , Streed, E.R. , Reichard, T.W. and Cattaneo, L.E.,

Provisional Flat Plate Solar Collector Testing Procedures: First

Revision, Nat. Bur. Stand. (U.S.), NBSIR 78-1305A (June 1978).

[10] HUD Intermediate Minimum Property Standards Supplement, 1977 Edition

Solar Heating and Domestic Hot Water Systems, No. 4930.2, Dept.

Housing and Urban Development, 1977.

[11] Interim Performance Criteria for Solar Heating and Cooling Systems

in Residential Buildings: Second Edition, Nat. Bur. Stand. (U.S.),

NBSIR 78-1562 (Nov. 1978).

[12] Interim Performance Criteria for Solar Heating and Cooling System

in Commercial Buildings, Nat. Bur. Stand. (U.S.), NBSIR 76-1187

(Nov. 1976).

[13] Recommended Requirements to Code Officials for Solar Heating,

Cooling and Hot Water Systems; Dept, of Energy, D0E/CS/34281-01

,

(June 1980)

[14] Safety Standards for Solar Collectors, Draft, Subject 1279,

Underwriters Laboratories Inc. (April 1979).

[15] Sherwood, G.E., Gatz, W.A.

,

Performance of Wood in a Do-It-Yourself

Solar Collector, Forest Products Laboratory, Research Note FPL-8240

(1979).

26
Figure 1. Site Plan

27
Figure 2 . House on lot 6

28
Figure 4. House on lot 24

Figure 5. House on lot 33

29
1 2 3 4 5

6 7 8 9 10

Lot 22

1 2 3 4* 5

6 7 8 9 10

Lot 33

* Collector Involved

In fire

Not to scale

Figure 6. Collector numbers

30
Tempered glass

Air space

Tempered glass

Air space

Absorber plate

Urethane foam

Plywood back

section

Solar collector

Rolled roofing

Sheathing

Glass fiber insulation

Gypsum board

2” x 8” joist

Figure 8. Roof section

31
Figure 9. Collector involved in the fire - view of plywood back

Figure 10. Collector involved in the fire view of interior side of plywood

32
SUM

Figure 11 . Collector 3 , lot 33

Figure 12 . Collector typical of lesser degradation

33
Figure 13. Collector typical of more severe degradation

Figure 14

Close-up view of collector with severe degradation

34
Figure 15. Back of collector with severe degradation
ELAPSED

TIME

(MINUTES)

120

180

240

300

360

420

480

540

600

(H313N DS/AA) 30NViavy«l

o a o a o

o a o a o o o o o

03 co CM o o o a o n V

^-9 CD to CM

(yw/u os/ruS) 33Nviovyyi

36

ELAPSED

TIME

(HOURS)

FIGURE

16.

SIMULATOR

SOLAR

IRRADIANCE

PROFILE.
Thermocouple Locations by Thermocouple Number

1, 6, 11 on backside of absorber

2, 7, 12 in foam 1/2" from absorber

3, 8, 13 in foam 1" from absorber

4, 9, 14 at interface of foam and plywood back

5, 10, 15 on plywood back

Figure 17. Location of thermocouples in collector

37
ELAPSED

TIME

(MINUTES)

120

180

240

300

360

420

480

540

600

Q

IX) CM o

CM

(0 030) 3dniVkJ3dW31

o o

m a o —« UD O

f

—— r

i — 1————r——-——r—— 1 o o o o o

0 030) 3«mvy3dN3!

o o o Q o o o o

m V CM

38

ELAPSED

TIME

(HOURS)

FIGURE

18.

TEMPERATURE

DISTRIBUTION

IN

COLLECTOR

MOUNTED

ON

TEST

FRAME.
ELAPSED

TIME

(MINUTES)

120

180

240

300

350

420

480

540

600

<0 030) 3MniVW3dW31

o o o o

id o in o o

CM CM —« —< LD O

r

1 1 1 1

1 O O O O O

o o o o o

o o o o o o

o o o o o UJ <o cm (J 030) 3HniVd3dW31

39

ELAPSED

TIME

(HOURS)

FIGURE

19.

TEMPERATURE

DISTRIBUTION

IN

COLLECTOR

MOUNTED

ON

INSULATED

ROOF

DECK.
Figure 20. Collector after 30-day stagnation exposure

40
Exposure

Day

Integrated

Solar Energy

W-hr/m^/day

Average

Temperature

°C

Average

Wind

m/ s

Precipitation

mm

1 6565 8.88 4.36

2 8565 6. 66 1.07

3 8468 7.8 2.31

4 6602 10.3 5.91

5 5191 6.4 2.26

6 7635 5.5 2.07

7 8410 6 .

1.69

8 9134 7.8 2.02

9 9000 8.8 1.86

10 8951 11.6 3.20

11 8796 11.6 3.06

12 9536 12.5 1.26

13 8068 7.8 1.82

14 9032 8.6 2.91

15 8896 12.5 5.55

16 8537 14.4 3.05

17 10486 11.9 3.25

18 7518 14.4 3.77

19 8290 12.8 2.27

20 8186 11.4 1.92

21 7906 10.0 3.21

22 8704 10.8 3.68

23 6125 14.4 4.49

24 8107 9.4 2.36

25 9978 6.9 1.42

26 8990 11.6 2.69

27 8257 7.8 1.89

28 9051 12.2 1.53

29 6865 12.8 4.54

30 6981 15.0 3.79

Figure 21. Collector exposure conditions

4.1
o

o

42

Figure

22.

Isothermal

weight

loss

of

polyurethane

foam
NBS-114A (REV. 2-80) U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR 2. Performing Organ. Report No. 3. Publication Date REPORT NO. | NBSIR 81-2326 September 1981

4. TITLE AND SUBTITLE

Solar Collector Fire Incident Investigation

5. AUTHOR(S)

William D. Walton

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions)

national bureau of standards

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

8. Type of Report & Period Covered

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

Department of Energy

Office of Solar Applications for Buildings

Washington, DC 20595

10.

SUPPLEMENTARY NOTES

| | Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

In May 1980, a fire involvings solar collector occurred in Boulder, Colorado in an unoccupied single family dwelling. Damage due to the fire was limited to a single

solar collector and adjacent roofing and framing materials. Collectors of the same model on three other dwellings at the site showed signs of degradation which may

have led to similar fires. The collector, installation, conditions leading to the

fite, and events following the fire are described. The most likely point of ignition

has been identified as the plywood collector backing. Results of a 30—day stagnation

test and solar simulator testing are discussed. Recommendations to prevent future

occurrences of this type of fire are presented.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

Building fires; fire safety; ignition; self —heating; solar collector fires;

solar collectors; spontaneous ignition

13. AVAILABILITY

[x] Unlimited

| | For Official Distribution. Do Not Release to NTIS

Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

t [7t] Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

45

15. Price

$6.50

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