A11100 ^4ti23

NAT'L INST. OF STAND & TECH I.C.

III III ! A111D5 aaTQS 1! NBSIR 81-2329

Characterizing the Thermal

Response of Fusible-Link

Sprinklers

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Washington, DC 20234

August 1 981

Final Report

c.2

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

NBSIR 81-2329

CHARACTERIZING THE THERMAL

RESPONSE OF FUSIBLE-LINK

SPRINKLERS

NATIONAL BUREAU

• Or STANDARDS

LIBRARY SEP 1 6 1111

7

David D. Evans

Daniel Madrzykowski

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Washington, DC 20234

August 1 981

Final Report

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

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
j . WOi

v.yio»

“X ' -• o
TABLE OF CONTENTS

Page

LIST OF FIGURES iv

LIST OF TABLES ..... ..... v

Abstract 1

1. INTRODUCTION 1

2. EXPERIMENTAL APPROACH 2

2.1 Apparatus for Thermal Response Measurements ..... 2

2.2 Sensing Element Instrumentation . . 3

2.3 Measurements . 4

3. DISCUSSION OF MEASUREMENTS 5

3.1 Energy Transfer 5

3.2 Models of Time Response 6

3.2.1 Single Parameter Model ..... 6

3.2.2 Two Parameter Model 8

3.2.3 Model Parameters Determined from Tests .... 10

3.2.4 Radiation and Conduction Effects 10

4. USE OF THE MODELS 12

5. CONCLUSIONS 15

6. REFERENCES 15

iii
7,1 ST OF FIGURES

Figure 1 .

Figure 2.

Figure 3.

Figure 4.

Figure 5.

Figure 6.

Figure 7.

Figure 8.

Figure 9.

Figure 10.

Figure 11.

Figure 12.

Figure 13.

Figure 14.

Figure 15.

Figure 16.

Figure 17.

Figure 18.

Thermal response measurement apparatus

Instrumented sprinkler A . . . .

Instrumented sprinkler B .

Instrumented sprinkler C ,

Sprinkler A, test link and gas temperatures . . . .

Sprinkler B, test link and gas temperatures . . . .

Sprinkler C, test link and gas temperatures . . . .

Apparent heat capacity of sprinkler A link

solder material , .

Areas associated with energy transfer,

sprinkler A . ........

Ln (AT -AT.) vs- time for sprinkler A

g i

Ln (AT^-AT^) vs time for sprinkler B

Ln (AT -AT ) vs time for sprinkler C

8

Polished brass disk .......

Ln (AT^-ATp) vs time for polished brass disk . . . .

Ln (AT -AT„) vs time for black brass disk

g A Brass disk mounted in sprinkler body ...

Ln (AT -AT ) vs time for polished brass disk

g

mounted in sprinkler body .............

Ceiling layer gas temperatures for mattress fire . .

Page

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

xv
LIST 0? TABLES

Page

Table 1. Test Results and Model Sprinkler Time Response

Parameters . . . . 10

Table 2. Predicted Activation Time for Pendent Sprinklers

in Mattress Fire 14

v

CHARACTERIZING THE THERMAL RESPONSE OF

FUSIBLE-LINK SPRINKLERS

David D. Evans ^ Daniel Madrzykowski

Abstract

Measurements of the thermal response of

selected fusible-link sprinklers to sudden

immersion into a hot gas flow are presented.

Two methods of characterizing the response

are detailed. One method explicitly accounts

for phase change, the other does not. The

methods are compared by using each to predict

the response of a sprinkler to a selected

mattress fire exposure.

Key Words: Fire extinguishment; fire models;

fire, protection; sprinkler heads; sprinkler

systems; time constant

1. INTRODUCTION

The overall effectiveness of an automatic sprinkler system in

suppressing an unwanted fire is dependent on the time it takes to

respond to the fire condition. Common automatic sprinkler systems are activated by hot combustion products, transported from the source fire,

which heat a thermal control element to a predetermined activation temperature. This temperature is usually associated with some part of the

sensing element undergoing phase transition.

In the specific case of the common solder type sprinkler link each

increment of energy transferred to the link from the fire in excess of

energy losses raises the temperature of the link and binding solder

^Presently at: Bechtel Corporation, Gaithersburg. Maryland

1
materials until the solder begins to fuse. At this temperature most

additional energy goes into completing the phase transition for the

solder and not into raising the link temperature. When enough solder

material has fused the link ruptures, activating the sprinkler head.

The predominant mechanism for heat transfer to a sprinkler link or other thermal sensor is by convection of hot combustion products. Heat

transferred by radiation during the initial fire growth period is of

X secondary importance [ 1 ] To predict the temperature of the thermal

sensing element and the time at which activation conditions are reached,

the thermal response characteristics of the sensor must be determined.

A useful method to characterize the thermal response of a sprinkler

linkage is to measure the temperature response of the link to sudden

immersion in a hot gas flow.

2. EXPERIMENTAL APPROACH

2.1 Apparatus for Thermal Response Measurements

Characterizing the response time of sprinkler links by sudden

immersion in a hot gas flow is the basis for the present Factory Mutual

Research Corporation (FMRC) plunge test [1]. For this study, an apparatus not as refined as the FMRC plunge test but sufficient for the

needs of this exploratory work was constructed.

Shown in figure 1, the apparatus consisted principally of a commercial heat gun to supply a forced hot air flow to an aluminum tube

(114 mm ID) with a deflector plate across the entrance to help diffuse

and mix the hot air flow. The gas temperature was measured continuously

near the tube outlet with a thermocouple suspended in the flow. For

Numbers in brackets indicate the literature references at the end of

this paper.

2
testing, sprinkler heads were placed in the supporting clamp at the

exit of the tube. The clamp is arranged in such a way that the sprinkler head could be held outside the hot air flow prior to testing, but

rapidly relocated into the center of the flow to initiate testing.

Generally the linkage on the head being tested was placed as close as practical to the exit of the tube without resulting in appreciable

blockage to the air flow. The nominal air flow velocity across the

tube outlet was 2.13 m/s. The turbulence level in the flow, although

known to affect the heat transfer ratio, was not measured.. The gas

outlet temperature could be varied by controlling the voltage applied

to the heating coils with an exterior variable transformer. However, a simple air flow temperature of 90°C + 4°C was used for these tests.

The aluminum tube wall was found to equilibrate at 60°C + 4°C under

test conditions in the laboratory.

2.2 Sensing Element Instrumentation

N .

Various methods of attaching thermocouple junctions to a fusible

link in order to measure its temperature were examined. No method of

attachment of a pre-welded junction to the face of the link proved

mechanically rugged enough for testing. In order to instrument a link,

two small holes were drilled opposite each other in the edge of the

disk and fitted tightly with one wire of an AWG-24 pair of Type K

thermocouple cable. The disk or link material formed the conducting

path between these junctions. In an effort to minimize conduction of

heat to the sensing element through the attached wires, each wire was

left electrically insulated up to the junction and also mechanically

formed to closely follow the edge of the link or disk. This method of

instrumenting the links proved to be both mechanically rugged and

repeatable without undue difficulty.

3
2.3 Measurements

The time response characteristics of three industrial sprinklers

were measured. Sprinklers A, B, and C are shown, instrumented, each

with a thermocouple connected to its thermal link; in. figures 2, 3 and

4. Each link had a labeled activation temperature of 74°C. Each

sprinkler was tested oriented such that the broad side of the thermal

link faced the upstream direction of the hot gas flow.

Figures 5, 6 and 7 show the temperature response of the three

thermal linkages in response to sudden immersion in the hot air stream,

the temperature of which is also recorded in the figures for the

duration of the test.

In each plot the temperature of the link is seen to increase in

response to the heat transferred from the hot air stream up to a point

when the. rate of temperature rise decreases abruptly. This abrupt

N . change in rate of temperature increase, which forms a plateau in the

time-temperature curve, indicates the onset of phase transition in the

links. Rupture of the link is indicated by the termination of the

temperature plot.

Focusing on figure 5, for sprinkler A, in the plateau region the

temperature is not constant, but undergoes a gradual rise from 71°C to

74°C. This behavior was shown to be reproducible in several tests.

The change in link temperature during solder fusion may indicate, that

the sample of solder material tested was not a true eutectic mixture,

or possibly experienced non-isothermal conditions during the testing.

The fusion characteristics of the solder material used in sprinkler

A were investigated with separate differential scanning calorimeter

(DSC) measurements. Data from the scan is presented in figure 8 in

units reflecting apparent, heat capacity of the sample. For the purposes

here, it is only necessary to note that melting in. the solder material

4
is not completed at a single temperature but bas two distinct peaks.

Very little energy is associated with the second peak near 74 °C compared

with the lower temperature phase transition peaking at 67°C. This DSC

data for the solder material would, suggest a temperature response as measured for sprinkler link A (figure 5) ; a plateau region representing

the low temperature phase transition, a slight temperature rise to the

second phase transition of short duration before link rupture. It

should be observed that even though the qualitative features agree, the

plateau in the response curve for sprinkler A (figure 5) is at approximately 72°C while a range of 63^ to 67°C was suggested by the low

temperature transition from the DSC measurements (figure 8) , The

reason for this discrepancy is presently unknown.

3. DISCUSSION OF MEASUREMENTS

3.1 Energy Transfer

An interesting parameter that characterizes one aspect of the

sprinkler link response is the fraction of energy needed to fuse enough

solder to rupture the link, compared to the total energy needed to heat

the link from ambient to rupture temperature. Ignoring the effects of

radiative heat transfer between the link and the surroundings and

conductive heat transfer with the sprinkler body, estimates of the

above energy ratio can be calculated from the information in figures 5,

6 , and 7

.

The convective heat, transferred to the link from the hot air

stream is proportional to the area between the outlet air temperature

curve shown in figures 5, 6 and 7 and the respective link temperature

curve. Figure 9 shows the two areas of interest for sprinkler A. The

fraction of energy involved with link fusion is

fusion energy _ Area A

rupture energy Area (A + B) ( 1)
For sprinklers A, B and C, this fraction of the energy associated with

the phase transitions in the solder, compared to the energy to rupture

the link from the respective 24.2 0 C 3 29.2°C, and 27.4°C, initial temperatures were: 0.26, 0.31, and 0.088 respectively. Sprinkler C,

which had the shortest time to rupture, or overall fastest response,

also had the lowest ratio of fusion energy compared to total rupture

energy.

3.2 Models of Time Response

The laboratory measurements made on the sprinkler heads established

the activation time for the linkage when exposed to a particular con- trolled hot gas flow. To predict the activation of the same linkage

under different gas velocity and temperature conditions a dynamic model

for the thermal response must be formulated. Two simple models will be

discussed.

3.2.1 Single Parameter Model

In the simplest model, the thermal response of the sprinkler

linkage is characterized by a single parameter t, usually referred to as a time constant. This time constant has its basis in a simple model

of the heat transfer process to the link. As discussed by Heskestad

and Smith [1], the equation governing the temperature-response of the

sprinkler link up to the temperature at which phase transitions begin

is

d(AT ) /dt = x

1 (AT - AT.) (2)

£ g a

where AT^ is the excess temperature of the link above the initial

temperature, and AT is the excess temperature of the gas above the

g

initial link temperature. The time constant, t, may be related to the

properties of the sprinkler linkage and the gas flow for convection

dominated heat tratisfer according to:

6
T = MC/h A ( 3 ) c

where M is the mass, C is the specific heat, A is the area of the link

exposed to gas flow, and h^ is the convective heat-transfer coefficient.

The value of h

c and thus x is dependent on the gas flow velocity

passing over the link.

When the fusible link reaches the temperature at which phase

transitions in the link solder begin, the temperature of the link

remains nearly constant and is no longer predicted by equation 2.

However, an overall time constant x, that includes both the effects of

thermal capacity and phase transitions in the linkage at a given gas

flow velocity, is a useful quantity to calculate.

Equation 2 may be solved for conditions that are appropriate to

model the test measurements made in this study, namely AT^ = 0 at t =

0 and AT is a constant. For these conditions, AT, as a function of

g l

time found from equation 2 is

AT

£ = AT (1 - e-t/x

) (4)

By simply measuring the time to link rupture, t^, in response to sudden

immersion in a hot gas flow and calculating the excess activation temperature, AT , the rupture temperature of the link either measured or

363. value, indicated on link minus the initial temperature of the link, an overall value for the time constant may be determined. In this study

this overall time constant will be labeled x^, From equation 4 its

value is:

= - Vln (1 - ^/ATg) (5)

If the data for the link temperatures shown in figures 5, 6 and 7 are re-plotted in the form

In (AT - AT) vs. t g *

( 6 )

7
then from equation 4 the slope of the curve will be, - 1/x. Figures

10, 11 and 12 show a re-plotting of the data from figures 5, 6 and 7 respectively as solid lines. From equation 5 the value, - 1/x^ equals

the slope of the straight line (shown as broken lines in figures 10, 11

and 12) connecting the first data point at time, t = 0 and the last

data point at link rupture. Thus the overall time constant x^ may also

be determined graphically.

This simple one parameter model for characterizing the thermal

response of the sprinkler linkage can be used effectively to predict

activation times, as will be discussed later, even though fusion of the

link solder is not explicitly modeled and deviations from the measured

temperature response are sometimes large. The method has an advantage

over the two parameter model, which will be discussed next, in that the

overall time constant, x^ , may be determined without measuring the link

temperature history. Only the initial link temperature (room temperature) , time to link rupture in hot gas flow, and rupture temperature

(link activation temperature) are needed to determine, x^.

3.2.2 Two Parameter Model

The single parameter model described in the previous section is

the simplest characterization of the thermal response of the sprinkler

linkage. As can be easily seen from figures 10, 11 and 12, there is a large deviation of the modeled link temperature compared to the measured

values. A better correspondence between measured and predicted link

temperature may be obtained from a two parameter model. For the two

parameter model, a time constant, is us^d to characterize the

response of the link up to the time of phase transition. Another

constant is introduced to characterize the time delay from the onset of

phase transition to link rupture.

To determine the two parameters for the model, two times must be

measured. As with the one parameter model, the time to link rupture,

x^_ , is needed. In addition, from plots of the experimental data such

8
as the solid lines in figures 10, 11 and 12, the time of an abrupt,

change in slope, t^, signifying the onset of phase transition is needed.

As with the single parameter model, a time constant, t

2

» can be calculated using equation 5 with t^ replaced by t^. Thus

T

2 - - t

p

/m <1 - AT

£a/AT

g

) (7)

The slope of the straight broken line from the initial data point

continuing to time t as shown in figures 10, 11 and 12, for the

sprinklers tested, is equal to - l/a^* The temperature at which this

line terminates, at time t^, corresponds to activation temperature of

the link.

The time delay from the onset of phase transition to link rupture,

t - t is determined from the experimental data. The temperature of

the link during this time interval is modeled as constant at the activation temperature. This corresponds to the horizontal broken line in

figures 10, 11 and 12.

This time delay itself is not a useful parameter for modeling the

sprinkler response, because it will vary with the rate of heat transfer

to the linkage. Applying the convective heat transfer analysis, a total energy transfer to the link during the time interval t to t can

p r be determined. This change in link energy associated with melting

enough solder in the link to cause rupture, is likely to be insensitive

to heat transfer rate. In the two parameter model this change in link

energy, AE, will be considered a parameter for the link.

Incorporating the simplification of the two parameter model, the

temperature of the link is constant over the time period from the onset

of phase transition to 3-ink rupture. Therefore the convective energy

transfer to the link during this time interval is:

AE = hA(AT

g

- AT

ta) (t, - t

p

> (8)

9
The quantity hA is determined from thus equation 8 becomes:

AE = MC ~ (AT - AT ) (t - t ) x 0 g la r p

( 9 )

The quantity AE/MC can be determined from the experimental data and is

a parameter for the linkage.

3.2.3 Model Parameters Determined from Tests

In addition to the values of the parameters characterizing the

response curves being indicated on figures 9 through 14, tabulated

values of experimental measurements and calculated parameters for the

three sprinklers are given in table 1.

Table 1

Test Results and Model Sprinkler Time Response Parameters

Sprinkler

V

“c

T

g’

°C

T

N - la r

°C

V

sec Vsec Vsec Vsec

AE/MC

°C

A 24.2 87.9 73.2 118 194 132 80.5 13.9

B 29.2 93.7 76.7 103 182 136 77.2 17.4

C 27.4 89.0 72.3 89 .106 81.2 68,2 4.16

3.2.4 Radiation and Conduction Effects

The analysis of data for thermal response of the sprinkler links

developed in sections 3.2.1 and 3.2.2 assumes that the heat transfer to

the links is dominated by convection. Radiation and conduction heat

transfer to the link are not considered in the analysis. The time

response characteristics of a machined brass disk similar in size and

geometry to common fusible links was studied under the same test conditions as used for the sprinkler measurements. These measurements form

a basis for qualitative discussion of radiation and conduction effects

in the test apparatus.

10
Figure 13 shows the polished brass disk suspended within a ring by

cotton threads. In this configuration radiation heat transfer between

the disk and the surroundings have been minimized by polishing the

disk. Conduction heat transfer between the disk and the metal support

is minimized by suspension of the disk with long cotton threads. Heat

transfer to the disk in this configuration should be dominated by

convection. Heat transfer to the disk from a constant temperature and

constant velocity air flow is characterized by a constant convective

heat transfer coefficient, h^. From equation 4, the value of the time

constant, t, will consequently be constant, and the slope of the thermal

response data on a plot of ln(AT^ - AT^) vs. time from equation 5 will

be a straight line.

Figure 14 shows the test data for the polished brass disk suspended

in the ring holder. This data falls along a straight line, indicating

that as initially assumed, in this apparatus convection alone is the

dominate mode of heat transfer to this disk. The slope of the straight

line indicates that the disk has a time constant of 97 seconds. Also

indicated on the graph is the point at which the disk temperature

reached 74°C. Normally this would be the termination point of common

fusible link tested.

Blackening the surfaces of the disk with a coating of carbon

black, and retesting it in the apparatus provide a set of response data

in which radiative heat transfer between the disk ana its surroundings

is favorable. Figure 15 shows that under these conditions, the response

data no longer forms a straight line as in figure 14. As the disk

increases in temperature, the data bends away from the initial straight

line which had a slope equivalent to a time constant of 97 seconds.

The change in slope of the data indicates a gradual increase in the

time constant, for the disk. This apparent increase in time constant is

the result of heat loss from the disk to its surroundings by radiation.

11
From the data in figure 15, which represents favorable conditions

for radiative heat loss in the apparatus, an estimate of the expected

influence of radiation in the test data for sprinklers A, R and C may

be obtained.

The blackened disk reached 74°C in 159 seconds. Using equation 5,

with an initial temperature of 20,. 3°C and gas temperature of 91.8°C,

the time constant for the disk would be calculated as 114 seconds.

This differs by only 18 percent from the value of 97 seconds based on

the initial slope of the curve. The influence of radiative transfer

could be further minimized by increasing the temperature of the gas

flow and thereby increasing the dominance of the convective, component

of heat transfer.

When the sprinkler link is installed in the body of the sprinkler

hear transfer between the body and the link by conduction can influence

the time constant of the link.'" For completeness, the polished brass

disk, already shown to minimize radiative heat transfer, was mounted in

place of the fusible link in a modified link and lever sprinkler body

as shown in figure 16.

This installation was tested. The response data is presented in

figure 17. The initial slope of the curve indicates that the installation of the brass disk in the sprinkler body has increased its time

constant to 119 seconds from the previous value of 97 seconds. The

increase in time constants indicates the disk is losing heat by con- duction to the sprinkler body, which because of its larger mass does

not heat as fast, as the link in the hot air flow.

4. USE OF THE MODELS

Each of the two models presented to characterize the response time

of sprinklers can be used to predict the activation time for sprinklers

given the air temperature and velocity history of the fire gases passing

12
the sprinkler head. This type of prediction has been done previously

by Alpert [2] using the one parameter model. Of particular inrerest in

this study is the comparison of the differences between the predicted

activation times in response to given fire conditions for the one and

two parameter models. Using data for the air temperature just below

the center ceiling from a test in which a polyurethane mattress was burned in a 3.35 m x 4.22 m x 2.35 m height room, predictions of the

activation time based on the two models of sprinkler response may be

made.

Although it is known that both the temperature, and velocity of the

air flow past a sprinkler influence its response time (Alpert [2]), for

the purpose of comparing the two response models velocity variation

will be neglected. For simplicity the velocity of the air flow will be

assumed constant and equal to the value used in the test apparatus,

2.13 m/s.

Figure 18 shows a plot of ceiling layer gas temperature vs. time

for the initial growth period of a typical mattress fire [3]. From,

this given gas temperature history, the activation time of each of the

three sprinklers tested, A, B and C using both the one and two parameter models may be predicted. Using the one parameter model calculation

of the activation time is straight, forward. Equation 2 may be integrated

numerically for AT

? as a function of time following a Runga-Kutta

procedure [4] using values of AT determined from figure 18 at five

second intervals, and measured time constant for the sprinkler of

interest. The time at which the predicted link temperatures reach the

value of activation temperature measured in the laboratory test, (approximately 74°C for the sprinkler examined in this study) is the predicted,

activation time.

Using the two parameter model, link temperatures up to the

activation temperature are predicted as above with time constant

replacing r^. In this case activation is delayed by the time necessary

13
to transfer heat used in fusing the material, AE/MC from equation 7.

Activation occurs when the critical value of AE/MC is reached, which

for the case of non-constant gas temperature is slightly more com- plicated than equation 9 and requires an integration over time of

t

AE/MC = — / (AT - AT )dt (10) J g la

tP

Table 2 presents the results of calculations for predicted

activation of each of the three sprinklers evaluated using the two

models. Predicted activation times using the single parameter model

span a range of 34.3 seconds, from 216.6 for sprinkler C to 250.9 for

sprinkler B, This reflects the faster response of an 81.2 second time

constant, (t^)

,

sprinkler compared to a 136 second sprinkler. In all

cases the two parameter model predicts a shorter activation time. The

difference is a slight 1.6 seconds for sprinkler C, and a greater 8.2

seconds and 8.7 seconds for sprinklers A and B respectively.

Table 2

Predicted Activation Time for Pendant Sprinklers in Mattress Fire

Activation Time

(Seconds)

Sprinkler A B C

One parameter model 243.2 250,9 216.6

Two parameter model 235.0 242.2 215.0

As would be expected, when the effects of phase transitions

represent only a small part of the response characteristic (figure 12)

of the sprinkler as in the case of sprinkler C, the one and two parameter models predict almost identical activation times, 216.6 seconds

and 215.0 seconds respectively. For sprinklers A and B, the effects of

phase transition are more pronounced (figures 10 and 11) and differences

14
in predicted activation times of slightly more than 8 seconds occur in

response to the selected mattress fire (figure 18). Overall, the differences in predicted activation times noted above are within the

expected accuracy of either model, as well as the degree of repeatability of thermal response between different specimens of the same model sprinkler.

5 . CONCLUSIONS

Measurements performed have shown that for selected fusible link

sprinklers, the amount of energy associated with fusion of the link can

be as much as 31 percent of the total energy transfer needed to rupture

a link which was initially at room temperature.

Using measurement of the link temperature response to sudden

immersion in a hot gas flow, two simple models can be formulated to

N * represent the thermal behavior. When used to predict sprinkler activation time in selected fire conditions, the models produce slightly

different results. The difference is, however, within the expected

accuracy of the predicted method and repeatability of the sprinkler

hardware

.

Radiation effects in the present laboratory measurement could

increase measured time constants by as much as 18 percent under worst

case conditions. Conduction through link arms in one sprinkler design

increase the measured individual link time constant by 23 percent.

6 . REFERENCES

[1] Heskestad, G. and Smith, H. , Investigation of a New Sprinkler

Sensitivity Approval Test: The Plunge Test. Factory Mutual

Technical Report, No. 22485, December 1976.

15
[2] Alpert, R. L., Calculation of Response Time of Ceiling-Mounted

Fire Detectors, Fire Technology , August 1972, p. 181-195.

[3] Hayes, D. H., Jr. and Zile, R. H. , Study of the Effect of

Location on the Activation Time of an Automatic Sprinkler,

NBSIR in process.

[4] Young, D. M, and Gregory, R. T., A Survey of Numerical

Mathematics Vol. 1 , Addison-Wes ley Publishing Company, 1972.

16
Figure 1. Thermal response measurement apparatus

17
Figure 2» Instrumented sprinkler A

18
Figure 3. Instrumented sprinkler B

19
Figure 4 Instrumented sprinkler C

2G
001

Q

</) O

z

o

o

bJ

</)

UJ

z

H

0 '3dniVd3dW31

21

figure

5.

Sprinkler

A

3

test

link

and

gas

temperatures
100

Q

<r,

)

q

z

o

o

bJ

(/)

\\ 3- 3dniVd3dW31

22

Figure

6.

Sprinkler

B,

test

link

and

gas

temperatures
100

Q

0 3dniVd3dW31

23

TIME

SECONDS

Figure

7.

Sprinkler

C,

test

link

and

gas

temperatures
3 9/1V3 AllOVdVO 1V3H !N3dVddV

24

TEMPERATURE
s

s

00

o

LU

00

<

oo s

Do ‘suniVdBdvm

5 CM

Figure

9.

Areas

associated

with

energy

transfer,

sprinkler
ggi s s s a 9

3o

‘ ;1V21V

26

Figure

10.

Ln

(AT

-AT )

vs

time

for

sprinkler
27

Figure

11.

Ln

(AT

-AT )

vs

time

for

sprinkler
Oo

,;lV“ 3iV

28

Figure

12.

Ln

(AT

-AT )

vs

time

for

sprinkler

5

X-
Figure 13. Polished brass disk

29
3o

‘ ;!V- aiV

'1

5

f

» f'

30

Figure

14.

Ln

(AT

-AT )

vs

time

for

polished

brass

disk
8

s

CM

CO

CO

§

aco

31

Figure

15.

Ln

(AT'

-AT )

vs

time

for

black

brass

disk
' ‘

' ^

Figure 16. Brass disk mounted in sprinkler body

32
3o ‘>1V " 3iV

33

Figure

17

.

Ln

(AT

-AT^)

vs

time

for

polished

brass

disk

mounted

in

sprinkler

body
250

Q

3 3dniVd3dW31

34

TIME

SECONDS

Figure

18.

Ceiling

layer

gas

temperatures

for

mattress

fire
NBS-114A (REV. 2-80

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

2. Performing Organ. Report No. 3. Publication Date

NBSIR 81-2329 August 1981

4. TITLE AND SUBTITLE

CHARACTERIZING THE THERMAL RESPONSE OF FUSIBLE-LINK SPRINKLERS

5. AUTHOR(S)

David D. Evans and Daniel Madrzykowski

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

Final Report

9.

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

10.

SUPPLEMENTARY NOTES

J 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)

Measurements of the thermal response of selected fusible-link sprinklers

to sudden immersion into a hot gas flow are presented. Two methods of

characterizing the response are detailed. One method explicitly aeccmnts for

phase change, the other does not. The methods are compared by using each

to predict the response of a sprinkler to a selected mattress fire exposure.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) Fire extinguishment; fire models; fire protection; sprinkler heads; sprinkler

systems; time constant

13. AVAILABILITY

[X^CUnl imited

| | For Official Distribution. Do Not Release to NTIS

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

20402.

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

14. NO. OF

PRINTED PAGES

39

15. Price

$6.50

USCOMM-DC 6043-P80
.

'

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