NBSIR 88-3715

JUL 1 4 1989

Measurement of Droplet Size in

Sprinkler Sprays

J. R. Lawson

W. D. Walton

D. D. Evans

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Gaithersburg, MD 20899

February 1988

Supported in part by:

The Swedish Fire Research Board

Stockholm, Sweden

and

75 Years Stimulating America'* Progreaa

1913-1988

General Services Administration

Washington, DC

NBSIR 88-3715

MEASUREMENT OF DROPLET SIZE IN

SPRINKLER SPRAYS

J. R. Lawson

W. D. Walton

D. D. Evans

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Gaithersburg, MD 20899

February 1988

Supported in part by:

The Swedish Fire Research Board

Stockholm, Sweden

and

General Services Administration

Washington, DC

U.S. DEPARTMENT OF COMMERCE, C. William Verity, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Table of Contents

Page

List of Tables iv

List of Figures v

Abstract 1

1. INTRODUCTION .......... 2

2. TEST APPARATUS AND DROPLET MEASUREMENT 3

3. APPARATUS CALIBRATION ..... 4

4. TEST PROCEDURE 5

5. TEST RESULTS 6

6. DROPLET SIZE COMPARISON AND ANALYSIS 7

6.1 MANUAL MEASUREMENTS 7

6.2 RESULTS OF COMPARISON 8

6.3 COMPARISON OF RESULTS WITH OTHER DATA 9

7. SUMMARY 11

8. ACKNOWLEDGEMENTS 13

9. REFERENCES 14

!

iii
List of Tables

Page

Table 1: Summary of test results 15 •

IV
List of Figures

Page

Figure 1. Photograph of strobe/camera module and sprinkler head 16

Figure 2. Photograph of sprinkler head under test 17

Figure 3. Photograph of video screen showing water droplets 18

Figure 4. Analyzer field orientation 19

Figure 5. Test volume 20

Figure 6. Radial test positions 20

Figure 7. Terms used to define analyzer position relative to sprinkler . 21

Figure 8. Vertical and horizontal test positions 22

Figure 9. Normalized cumulative volume and cumulative number vs.

diameter, Test No. 1 (1 i/s, 90°, 90°) 23

Figure 10. Normalized cumulative volume and cumulative number vs.

diameter, Test No. 2 (1 i/s, 90°, 64.7°) 24

Figure 11. Normalized cumulative volume and cumulative number vs.

diameter, Test No. 3 (1 i/s, 90°, 46.6°) 25

Figure 12. Normalized cumulative volume and cumulative number vs.

diameter, Test No. 4 (1 i/s, 90°, 27.9°) 26

Figure 13. Normalized cumulative volume and cumulative number vs.

diameter, Test No. 5 (1 i/s, 90°, 0°) 27

Figure 14. Normalized cumulative volume and cumulative number vs.

diameter, Test No. 6 (2 i/s, 90°, 90°). 28

Figure 15. Normalized cumulative volume and cumulative number vs.

diameter, Test No. 7 (2 i/s, 90°, 64.7°) 29

Figure 16. Normalized cumulative volume and cumulative number vs.

diameter, Test No. 8 (2 i/s, 90°, 46.6°) 30

Figure 17. Normalized cumulative volume and cumulative number vs.

diameter, Test No. 9 (2 i/s, 90°, 27.9°) 31

Figure 18. Normalized cumulative volume and cumulative number vs.

diameter, Test No. 10 (2 i/s, 90°, 0°) 32

Figure 19. Normalized cumulative volume and cumulative number vs.

diameter, Test No. 11 (2 i/s, 0°, 90°) 33

Figure 20. Normalized cumulative volume and cumulative number vs.

diameter, Test No. 12 (2 i/s, 0°, 64.7°) 34

Figure 21. Normalized cumulative volume and cumulative number vs.

diameter, Test No. 13 (2 i/s, 0°, 46.6°) 35

Figure 22. Normalized cumulative volume and cumulative number vs.

diameter, Test No. 14 (2 i/s, 0°, 27.9°) 36

Figure 23. Normalized cumulative volume and cumulative number vs.

diameter, Test No. 15 (2 i/s, 0°, 0°) 37

Figure 24. Aggregate normalized cumulative volume and cumulative

number vs. diameter for Tests No. 1 - 5, (2 i/s) 38

Figure 25. Aggregate normalized cumulative volume and cumulative

number vs. diameter for Tests No. 6 - 10 (2 i/s) 39

Figure 26. Aggregate normalized cumulative volume and cumulative

number vs. diameter for Tests No. 11 - 15 (2 i/s) 40

Figure 27. Normalized cumulative volume and cumulative number vs.

diameter for droplets captured in oil Test No. 1 (1 i/s) ... 41

Figure 28. Normalized cumulative volume and cumulative number vs.

diameter for droplets captured in oil Test No. 2 (2 i/s) ... 42

v
Figure

Figure

'

29 .

30 .

Experimental verification of We

~ 1/3 prediction

for water spray nozzles .....

Volume median diameter vs. position angle ....

'

.

vi
MEASUREMENT OF DROPLET SIZE IN SPRINKLER SPRAYS

Abstract

A computer controlled video shadowgraph was used to collect data on the spray

characteristics of a commercially available sprinkler head. A total of 15

tests were carried out that measured spray characteristics at different

positions close to the sprinkler head. Tests were conducted using two

different water flow rates, one and two liters per second. Droplet diameters

were measured and analyzed to produce graphic presentations of normalized

cumulative volume and cumulative number vs. droplet diameter data. In

addition, a comparison was made between the droplet diameters measured using

the video analyzer and droplet samples collected in a light oil and measured

manually using a microscope. The data are also compared with results found in

the literature. Data on more than 66,000 spray droplets were collected and

used for analysis in the development of this report.

Keywords: Drop size measurements, droplets, water sprays, sprinkler heads,

sprinkler systems.

1
1 . INTRODUCTION

Fire growth and extinction in a structure embodies the interaction of many

complex phenomena that are becoming better understood through research efforts

at the National Bureau of Standards and other fire research facilities around

the world. As part of this increased knowledge, methods for estimating the

influence of water sprays on fires and extinguishment have evolved. Several

computer models have been developed in the fire research community that

address the interaction of water sprays with fire driven flows [1,2]. Each of

these computer models, as well as other analysis of heat and mass transfer

effects between sprays and hot gas flows, require accurate input data

characterizing water droplets that are generated by a common sprinkler head.

Water droplet size distribution from a sprinkler head can greatly change the

characteristics of fire growth and the transport of hot gases within

structures. The data gathered during this study is designed to provide some

of the information necessary to exercise these computer models.

2
2. TEST APPARATUS AND DROPLET MEASUREMENT

The test apparatus used in this study is a commercial instrument produced by

Bete Fog Nozzle Inc. 1 The apparatus used is a computer controlled video

shadowgraph. This equipment is controlled by custom software used to

accurately measure droplet size in a sprinkler spray. The apparatus consists

of four major components: the computer, video analyzer, video camera, and high

intensity strobe system [3]. 2 The strobe and video camera module is shown in

Figure 1. The photograph in Figure 2 shows an example of the analyzer with a

sprinkler head being tested.

The video camera is used to capture water droplet shadow images produced by a

high intensity strobe fired on the other side of the sample volume. See

Figure 3. Image data from each video frame is stored in a computer file for

processing after a multi-frame test is completed. Droplet shadow area is

determined by multiplying the number of video pixels per drop by a calibration

constant which depends on the magnification used. The reported diameter for

the droplet is the diameter of a circle that has the same projected area as

the measured image. Thus non-circular images resulting from the image of

non- spherical drops are reported as effective spherical diameters. The

1 Certain commercial equipment, instruments, or materials are identified

in this paper in order to adequately specify the experimental procedure. Such

identification does not imply recommendation or endorsement by the National

Bureau of Standards.

Neither the contents of this report nor the fact that the tests were made at

the National Bureau of Standards shall be used for advertising or promotional

purpose

.

2 Figures in brackets indicate literature references at the end of this

report

.

3
droplet analyzer can measure droplets over a range from 3 microns to more

than 21,000 /jm (21 mm) by installing various optical lenses [3], The size

range for droplets of interest in this study was from 100 to 2000 /jm (0.1 to

2.0 mm). Information on optics selection for the above droplet size range is

contained in section 3.

3 . APPARATUS CALIBRATION

Before any tests are conducted, the test apparatus must be properly configured

and calibrated to insure that accurate test data are generated. It is

important that proper camera lenses be selected for the droplet analyzer when

a particular droplet size range is being studied. In this test program,

measurement of water droplet diameters as large as 2000 /zm were required. The

camera lens combination adopted for these tests provided a magnification of

approximately 1.1 power which permitted resolution of drops as small as 100 /zm

and as large as 2000 /zm. The sample field of view, as shown in Figure 4, for

this optical arrangement was experimentally measured by positioning a target

within the video field and moving it from side to side and up and down.

Figure 5 shows the sampling volume used in these tests. The field of view

provided by the lens combination used in this study was 21.7 mm wide and

17.3 mm high and approximately 5 mm depth. Droplets were admitted into the

sampling volume through two vanes separated by 5 mm and located at a 77 mm

radius from the center of the sampling volume. Thus, all drops measured may

be considered as traveling perpendicular to the direction of illumination used

to form the shadowgraphic images on the video display.

4
Calibration of distances and pixel area on the video image was accomplished by

measuring balls of known diameter placed in the measurement volume. Software

calibration constants were entered into the image analysis program based on

these measurements

.

4 . TEST PROCEDURE

In order to characterize the spray from a selected nominal 15 mm diameter

pendent sprinkler head, water droplets were measured at several locations

parallel and perpendicular to the sprinkler frame arms (Figure 6) . Before

testing, one of the sprinkler frame arms was marked and designated 0 degrees

cylindrical angle. Other terms used to identify analyzer position relative to

the sprinkler head are centerline coordinate, radial coordinate, distance from

nozzle and azimuthal angle. All terms are defined by the sketches in

Figure 7.

The droplet analyzer was used to make measurements at five positions with a 0

degree orientation relative to the sprinkler head. The sprinkler head was

then turned 90 degrees relative to the analyzer and another series of tests

was conducted. During the test program, the analyzer was never placed closer

than 240 mm from the sprinkler head in order to stay just beyond sheet breakup

of the water spray. Figure 8 describes the test measurement locations.

A total of ten tests were conducted at the position 90 degrees to the frame

arms, five tests at a flow rate of one liter per second and five tests at a

5
flow rate of two liters per second. All five tests at the 0 degree position

were made with a water flow rate of two liters per second.

5. TEST RESULTS

The results of the fifteen tests are summarized in Table 1. Given in the

table for each test is the flow rate, cylindrical angle (Figure 7) and

position angle (Figure 8). Table 1 includes the number of frames per test,

total number of drops analyzed, mean droplet diameter, volume mean diameter,

median diameter, volume median diameter and the total droplet volume for each

of the tests. The mean diameter is the sum of the diameters divided by the

number of drops. The volume mean diameter is the diameter of a drop whose

volume is the sum of the volumes of all of the drops divided by the number of

drops. The median diameter is the diameter of a drop for which half of the

drops have a larger diameter and half a smaller diameter. The volume median

diameter is the diameter of a drop for which all of the drops larger than that

diameter have an aggregate volume equal to half of the total volume of all of

the drops.

Plots of the size distributions have been given for each of the tests in

Figures 9-23. The plot for the positions measured shows the cumulative

number and cumulative volume vs. diameter information normalized using the

total number of drops measured and the total volume of the drops measured

respectively. The median drop diameter and volume median diameter can be read

directly at 0.5 on the ordinate. The average diameter and average volume

diameter are indicated on the respective curves. Figures 24 - 26 are

6
aggregate information for each of the three flow rate, cylindrical angle

combinations. These plots show the combined distributions over the five

position angles measured in each case.

6. DROPLET SIZE COMPARISON AND ANALYSIS

Both manually measured droplets from the sprinkler spray and comparisons with

available published data were made as checks on the automated analysis.

6.1 MANUAL MEASUREMENTS

A 89 mm wide by 19 mm deep glass petri dish with a cover was used to collect

the water droplet samples from the water spray emitted from the test sprinkler

head. The petri dish was half filled with pharmacy grade castor oil (oleum

ricini) . The cover was placed on the dish until it was opened at the desired

location in the water spray. Droplets were allowed to collect in the oil for

about one second, and then the cover was placed back on the petri dish. The

dish was removed from the spray field, and the exterior was dried. The cover

was removed, and the dish containing the oil and water droplets was placed

under a microscope. The microscope eyepiece had a calibrated graduated scale

that was used for measuring the water droplets. The scale was calibrated

using a precision microscope slide with circular dots of known size. A sample

of as many as 55 droplets was measured from each specimen taken. The largest

and smallest drops were cataloged for each petri dish specimen. Samples were

taken with water flow rates of one and two liters per second.

7
6.2 RESULTS OF COMPARISON

One sample was taken on a horizontal plane at a location with a cylindrical

angle of 90° to the sprinkler frame arms and position angle of 90° from the

sprinkler head. This corresponds to the position measured in test 1,

Figure 9. Water flow rate for this sample was one liter per second. From

this sample, a total of 53 droplets were measured. The diameter of the

largest droplet measured was 1261 /xm and the smallest was 90 /xm. The 90 /xm

value represents the limit of resolution for the microscopic measurement. The

mean volume diameter was 465 /xm. This sample compares well with the mean

volume diameter obtained from the same sprinkler spray location in test 1.

The mean volume diameter measured by the droplet analyzer for that test was

451 /xm. This is a difference of less than 4 percent. Figure 27 provides

plots of normalized cumulative number and normalized cumulative volume vs.

diameter for the 53 droplet sample taken in oil. These distributions show

good agreement with those of test 1.

The water flow rate was changed to two liters per second, and another spray

sample was taken at a position located approximately 240 mm below and 254 mm

away from the sprinkler head centerline. This corresponds to the position

examined in test 8, shown in Figure 16. The sample was again taken

perpendicular to the sprinkler frame. In this sample 55 droplets were

measured. The droplet diameters ranged from 90 to 720 /xm with a mean volume

diameter of 308 /xm. The mean volume diameter determined by the analyzed in

test 8 at the same location was 385 /xm. These results represent a difference

of only 25 percent between manual and automated measurements. Figure 28

8
provides plots of normalized cumulative number and normalized cumulative

volume vs. diameter for the 55 droplet sample in oil. These plots when

compared to those of test 8 (Figure 16) do not agree as well as those the

previous set. This is primarily due to the relative lack of large droplets in

this samplecollected manually.

6.3 COMPARISON OF RESULTS WITH OTHER DATA

Correlations of spray droplet diameters for several commercial sprinklers have

been reported by Dundas [4]

.

The correlation of data from the Dundas' study is shown in Figure 29. The

data from this study are presented along with data from Dundas [4]

,

Braidech

and Neale [5], and Kroesser [6] as the dimensionless droplet diameter (median

volume diameter divided by sprinkler orifice diameter) plotted as a function

of Weber Number (We

)

.

dm/d a we = (P u

2 d / a) ( 1 )

where

d = sprinkler orifice diameter

dm = volume median diameter of water droplets

u = velocity of water flow at the sprinkler orifice

p = water density

a = surface tension of water-air interface

9
The data from this study has been reduced to three points representing the

aggregate analysis which combines all the data from the different position

angles measured at the separate flow rates and cylindrical angles. Notice

each of these three points is the result of analysis performed on

20,000 - 25,000 droplet diameter measurements!

Figure 30 shows all 15 measured volume median droplet diameters vs. position

angle points. Directly under the sprinkler is referred to as the 0° position

angle, while the 90° position angle is in the plane of the sprinkler deflector

plate. For the two sets of data at 90° cylindrical angle, which is

perpendicular to the plane of the frame arms, the lower flow rate produces

larger volume median droplet diameters as would be expected. However, what

appears to be an outlier data point at 46.6° position angle and 1232 /im

diameter is actually quite close to the expected variation between the 1 Z/s

and 2 Z/s flow rates based on We

“

1 /

3

variations. The expected ratio of volume

median diameter for the low flow rate to high flow rate is:

( 1 Z/s )

' We

( 1 i/s ) -p/3 r 16200 V 1/3

( 2 i/s ) . We

( 2 i/s ) J 64800 J

D—m (li/s) — — = 1.59

Dm ( 2 Z/s )

The measurement values at 46.6° position angle are 1232 /^m for the 1 Z/s flow

rate and 736 /zm for the 2 Z/s flow rate. The ratio is 1.67, which is close to

the expected result. It follows, the "agreement" in four other position

10
angles measured between the two flow rates at the 90° cylindrical angle are

actually unexpected results.

Measurements in the plane of the frame arms ( 0° cylindrical angle ) show a

deficit of large drops over the mid-range of position angles from 40° to 70°

.

This is the result of the frame arms blocking the flow.

For a spray as complex and non-uniform as that from a common fire protection

sprinkler, there are considerable changes in spray pattern when the flow rate

is doubled. This diminishes the values of detailed spatial comparisons as

presented in Figure 30 and supports use of aggregate quantities such as those

found in Figure 29 which average over the spray pattern from the sprinklers.

7 . SUMMARY

A series of experiments was carried out to measure and collect information on

sprinkler head spray characteristics. A computer driven video shadowgraph

technique to collect water droplet data on the sprinkler head sprays was used.

The data were reduced, analyzed and compared with other existing data. This

data comparison showed good agreement. Water droplets were also collected

using castor oil and then measured using a microscope. The comparison of

droplet analyzer distributions obtained from the analyzer with those

calculated from manual sizing of a small number of drops collected in caster

oil showed very good agreement in one of two cases. The data generated during

this study was collected and presented in a manner that would allow it to be

used in the evaluation of sprinkler heads or to be use in development of fire

11
growth and extinguishment computer models. Values of median volume diameter

averaged over portions of the spray agreed well with previously measured

values for commercial sprinklers when correlated by the Weber number. For the

15 mm pendent sprinkler with an 11 mm orifice diameter, median volume

diameters of 943 /an and 703 /an were found for 1 i/s and 2 i/s flow rates

respectively at positions in the spray perpendicular to the plane of the frame

arms. The median volume diameter decreased to 575 /^m in the plane of the

frame arms at a flow rate of 2 i/s.

12
8 . ACKNOWLEDGEMENTS

Appreciation is extended to Mr. Emil Braun of the Center for Fire Research for

his assistance in developing the data transfer routines used in this project

and helping with other computer related efforts. Mr. Paul Bennett of Autodata

Engineering Software is recognized for his assistance in creating a unique

computer program for collecting and displaying test data from the droplet

analyzer. The management and technical staff of Bete Fog Nozzle Inc. provided

advice and assistance on experimental technique and equipment throughout the

proj ect

.

13
9 . REFERENCES

[1] Alpert, R. L. , Delichatsios , M. M. , Calculated Interaction of Water

Droplet Sprays With Plumes in Compartments, NBS -GCR- 86 - 520 , National Bureau of

Standards, U.S.A., 1986.

[2] Ball, J. A., Pietrzak, L. M. , Investigation to Improve the Effectiveness

of Water in the Suppression of Compartment Fires, Fire Research, 1, No. 4/5,

Netherlands, 1977-78.

[3] Droplet Analyzer System Operators Manual, Bete Fog Nozzle Inc.,

Greenfield, MA (1985)

.

[4] Dundas P.H., THe Scaling of Sprinkler Discharge: Prediction of Drop Size,

Progress Report No. 10, FMRC Serial No. 18792, RC73-T-40, Factory Mutual

Research Corporation, Norwood, Massachusetts, 1974.

[5] Braidech, M.M. and Neale, J.A., "The Mechanism of Extinguishment of Fire

by Finely Divided Water", NBFU Research Report No. 10, Underwriters'

Laboratories, Inc., 1955.

[6] Kroesser, F.W.

,

"The Measurement of Drop Sizes Produced by the Discharge

of Water From a Sprinkler", FMRC Serial 18792 Technical Report, August 1969.

14
Test

No.

Flow

Rate

Cylindrical

Angle

Position

Angle

Number

of

Test

Droplet

Count

Mean

Volume

Mean

Median

Volume

Median

Total

Volume 3

(

S/s )

(degrees)

(degrees)

Frames

(mm )

CM

CD

CO

CD

CD m

eg

CD

O) egCD

CDCD

CM

COCD

CM

OmCD

CD

CD

CM

CD

CD -3- CM

CO CD CO

CD cm

CO CD rH

CO O CD

cd m cd

CD G)

CO CO CD

cd co

ID rH

CD cn

(D CD

CD CD

CO CO

CDO

CM

CM O rH CO

CD rH CO

CM CO CO

<r CO IT) CD CD <r CM CM CMCD CO rH rH

cd CD CM CM CM CMeg

CM

CO<

CM

co

-3- CM

rH CD m co

•3* nr

<r CD CM CO CD CD cd in coCO rH -3 m co co 3 CO *3* oU-)

COCD

CO

CO 3

CM O

3 co

CD

rH

CO

CO

rH3

in cm co CO CO rH CO CM

CO CO 3 3 CO

CO CD m co CO CM

eg

CO mCO

co -3- m

O rH m

CO CO CM

CO CO CD O

cm co

o eg o CM 3 n CM CO n 3 co m 00 rH rH CM o CD CD in eg rH rH rH CD CD O m CM o CD CD CD o O o O CD CO

*3* 3 *3- 3 CO CO CD *3- -3- •3" CO CO

rH CO 3 cm

CM

rH CD

CO CD CM CO

CD

CD CO CD rH m

O CD

co3

O CDcd

O CD CD O

O 3 CD rv O

CD CD *3* CM

O CD CD o O 3 CD o

CD CD 3 eg

o CD CD O o 3 CD o

CD CD 3 CM

o o CD CD o o

CD CD O O

CD CD O O

CD CD OCD O

CD O O o o o

o

CM OCM o oeg eg o oCM CM oCM o o oeg cm cm

rH cm co 3 m CD oo CD cm co *3- «n

rH rH rH rH

15

4013

259

304

221

383

58.
Figure 1. Photograph of strobe/camera module and sprinkler head

16

V'

''''
Figure 2

.

Photograph of sprinkler head under test

17
Figure 3. Photograph of video screen showing water droplets

18
Sprinkler

head

22®®

Q.E

(8

</)

19

Figure

4„

Analyzer

field

orientation
Figure 6: Radial test positions.

20
Centerline

Coordinate

Radial

Coordinate

Video

image

area

Figure 7. Terms used to define analyzer position relative to sprinkler.

21
fflo

Figure 8: Vertical and horizontal test positions.

22

mm
NUMBER

LU

O

>

awmoA ivioi/awmoA BAiivnnwno

B3awnN nvioi/d38wnN 3Aiivnnwno

23

Figure

9.

Normalized

cumulative

volume

and

cumulative

number

vs.

diameter,

Test

No.

1

(1

i/s,

90°,

90°)
.00

i

r

—

—

r

—

i—

—i

~

1

\j

'

"

—

~T

!

NUMBER

LU

O

>

o o o o o O o o o o

cn CD h- LD LD cn OJ t o

o o o O O o o o o o

tnc

o

L,U

CC

LU

!

LUS

<

HH

Q

3wmoA nvioi/3wmoA SAiivnnwno

d30wnN nvioi/d30HnN 3Aiivinwno

24

Figure

10.

Normalized

cumulative

volume

and

cumulative

number

vs.

diameter

,

Test

No.

2

(1

i/s,

90°,

64.7°)
NUMBER

UJ

o

>

3wmoA ivioi/awmoA 3Aiivnnwno

B3awnN nvioi/d3GwnN 3Aiiv“inwno

cnc

o

c_CJ

crUJ

i—

UJ

<

i—

i

o

25

Figure

11.

Normalized

cumulative

volume

and

cumulative

number

vs.

diameter,

Test

No.

3

(1

£/s,

90°,

46.6°)
cr LU

LU 2

CD ZD

2: U

ZD O

~ZL >

awniOA nvioi/awmoA aAiivmwno

uaawnN ivioi/uaawnN aAiivinwno

26

Figure

12.

Normalized

cumulative

volume

and

cumulative

number

vs.

diameter,

Test

No.

4

(1

i/s,

90°,

27.9°)
NUMBER

lli o

>

o

o

o

C\J

o

o

CD

o

o

ID

o

o

'T

o

o

C\J

o

o

o

o

o

CD

o

o

CD

O

^r

o

o

oj

c

o

c_u

crLU

LU

<

—

i

Q

3wmoA nvioi/3wmoA 3Aiivnnwno

fcl3QWnN lVlOl/U30WnN 3AIlV“inwn3

27

Figure

13.

Normalized

cumulative

volume

and

cumulative

number

vs.

diameter,

Test

No.

5

(1

i/s,

90°,

0°)
c LU

LU 2: CD ZD

21 _J

ZD o

Z >

gwmoA ivioi/awmoA 3Aiivmwno

H38wnN nvioi/aaawnN 3Aiivmwno

28

Figure

14.

Normalized

cumulative

volume

and

cumulative

number

vs.

diameter,

Test

No.

6

(2

J!/s,

90°,

90°)
NUMBER

UJ

0

>

1 o

ocncDr^tDin^rcnc\j't-io <^0000000000

3wmoA ivioi/3wmoA 3Aiivnnwno

B3awnN nvioi/d3SwnN 3Aiivnnwno

tnc

o

c_

CJ

ccLU

I—

LU

IE

<

t—

1

O

29

Figure

15.

Noramlized

cumulative

volume

and

cumulative

number

vs.

diameter,

Test

No.

7

(2

i/s,

90°,

64.7°)
.

00

i

—

—

—

—i

—

r~

!

i

i

,

"'

Tn

i

i

i

~n

NUMBER

LU

21

ZD

_JO

>

o o O o o o o o o o

CD 03 r^ to ID cn OJ o

O O o o o o o o O o

cnc

o

c_u

CE

LU

I—

LU

<

h—

I

o

3wmoA nvioi/3wmoA 3Aiiv“inwno

d39wnN nvioi/tGSNnN 3AiivnnNn3

30

Figure

16.

Normalized

cumulative

volume

and

cumulative

number

vs.

diameter,

Test

No.

8

(2

i/s,

90°,

46.6°)
NUMBER

UJ

:zZD

_i

>

o

oooooooooo

awmoA nvioi/awmoA 3Aiivinwno

H39wnN nvioi/tiaawnN aAiivnnwno

C/3 c

o

c_u

cr

LU

i—

LU

:z<

t—

i

Q

31

Figure

17.

Normalized

cumulative

volume

and

cumulative

number

vs.

diameter,

Test

No.

9

(2

i/s,

90°,

27.9°)
CL UJ

LLJ 21

CD Z>

2: _l

Z5Z >

o

o

o

C\J

o

o

GO

O

CO

O

o

^r

o

o

C\J

o

o

o

o

o

00

o

o

CD

o

o

o

o

CM

tnc

o

L,U

cr

LU

h~

LU

<

HH

Q

awmoA ivioi/awmoA 3Aiiv~inwno

aaawriN nvioi/aaawnN aAiivinwra

32

Figure

18.

Normalized

cumulative

volume

and

cumulative

number

vs.

diameter,

Test

No.

10

(2

J?/

s,

90°

,

0°)
NUMBER

LU

O

>

C/D C

o

c_

cj

cc

LU

f—

LU

<

i—

i

O

cno

CD

o o

CD

O

in

o

^r

o

cno

C\J

o

o

o

3wmoA nvioi/awmoA 3Aiiv"inwno

d3swnN ivioi/asawnN 3Aiivnnwno

33

Figure

19.

Normalized

cumulative

volume

and

cumulative

number

vs.

diameter,

Test

No.

11

(2

i/s

,

0°,

90°)
NUMBER

LU

O

>

I o

o

o

ai

o

o

CD

^“1 o

o

CD

O

o

o

oj

o

o

o

o

o

CD

o

o

CD

O

o

o

a

o

m

c

o

c_u

c

LU

(—

LU

:z<

hi

O

3wmoA nvioi/3wmoA 3Aiivnnwno

d3awnN ivioi/ti38wnN 3Aiiv~inwno

34

Figure

20,

Normalized

cumulative

volume

and

cumulative

number

vs.

diameter.

Test

No.

12

(2

i/s,

0°,

64.7°)
NUMBER

LU

O

>

cno

coo oLO

O

ID

O o

CO

o

OJ

o

awmoA nvioi/3wmoA 3Aiiv~inwno

lgghhn ~ivioi/u3awnN 3Aiivnnwno

o

o

cnc

o

c_o

c

LU

I—

LU

<

1—

1

O

35

Figure

21.

Normalized

cumulative

volume

and

cumulative

number

vs.

diameter.

Test

No.

13

(2

&/s,

0°.

46.6°)
c Ld

Ld 2: m 3

:e3 O

3 >

I o

3wmoA nvioi/awmoA 3Aiiv"inwno

«3awnN nvioi/u39HnN 3Aiivnnwn3

m

c

o

c_u

CE

LU

LdS

<

I—

!

Q

36

Figure

22.

Normalized

cumulative

volume

and

cumulative

number

vs.

diameter,

Test

No.

14

(2

i/s,

0°,

27.9°)
NUMBER

LU

O

>

CD

O

CD

O o

CD

O

ID

O O

cnoOJ

o

awmoA “ivioi/3wmoA 3Aiivnnwno

ti3QwnN nvioi/d38wnN 3Aiivnnwno

o

o

cnc

o

c_u

cn. LU

I—

LU

<

i—

1

O

37

Figure

23.

Normalized

cumulative

volume

and

cumulative

number

vs.

diameter,

Test

No.

15

(2

2/

s,

0°,

0°)
NUMBER

LU

3

_JO

>

awmoA nvioi/awnnoA aAXivmwno

aaewnN nvioi/aaawnN aAiivnnwno

38

Figure

24.

Aggregate

normalized

cumulative

volume

and

cumulative

number

vs.

diameter

for

Tests

No.

1

-

5,

(2

f/s)
NUMBER

UJ

2:

ID

I O

>

Cfi c

o

c_u

cc

LU

I—

LU

<

1—

1

Q

CD

O

CD

O o

CD

o

in

o o

cno

CM

O

o

o

3wmoA nvioi/3wmoA 3AiivinHno

d3swnN nvioi/d39wnN 3Aiiv~inwno

39

Figure

25.

Aggregate

normalized

cumulative

volume

and

cumulative

number

vs.

diameter

for

Tests

No.

6

-

10

(2

i/s)
CL LU

LU 21

CD 3

21 _J 3 O

z: >

I o

gwmoA 'ivioi/swmoA 3Aiivnnwno

tisawnN nvioi/u39wnN SAiivnnwno

40

DIAMETER

(microns)

Figure

26.

Aggregate

normalized

cumulative

volume

and

cumulative

number

vs.

diameter

for

Tests

No.

11

-

15

(2

i/s)
cr LU

LU 21

CD ZD 2: 1 ZD O 2 > O

OJO

w

CD • \ T—1

co>

I-I

5-1 '—

O 03 r—1 E

LO 3 •

”<-“1 c 02

(1) > 4-> *r4 CO

O 4-3 <D

cC

H

i-i rH 3 r—1 £ •i-l O 0 0 cn T3 c

•1—1 0 C

ru c0

c_

02

<D

T3

0)

3-i 0 | 3

4-1 •I—1 1—1 D. 0 E O 03 0 — > O 0

vt cr

03>

CO

4-> LU •H 03 1— 4J 1—4 0

LU2

03 r-1 3 a0

S-i 0 < E 33 CD 1—1 3 O O 3-1 0

-3 4-1

03CO 3-i

O *r-i 03 O 1—1

4-3 LD COE

0)E U 03 O •t-H 2 03

O •

CNI

03

3-1 3 0 40 0

OJ0 O O O 0 O O O 0 0 0

OD CD LO LD oq- CO OJ Vi 0 O O 0 O O O 0 0 0 0

awmoA nvioi/3wmoA 3Aiiv“inwno

d3awnN nvioi/d3awnN 3Aiiv~inwn3

41

CL

LU

I—

LU2<l—l O

crUJ

1—

LU

2:<

1—1 O

LU

21

ZDO> < <

LU LU
VOLUME

o

0 0 O 0 O 0 0 0 0 O

cn CD ID in CO OJ O

0 O 0 O 0 0 0 0 O O

m

c

o

L.U

CL

LU

t—

LU

<

h1

o

3wmoA nvioi/3wmoA 3Aiivnnwno

usewriN ivioi/a3SwnN 3Aiivinwno

42

Figure

28.

Normalized

cumulative

volume

and

cumulative

number

vs.

diameter

for

droplets

captured

in

oil

Test

No.

2

(2

i/s)
T ID

o

D

(0 CO <c •“o •—o e _o

k.

"O "D “O

<J) •- •- £

CO

CO co

ID O)

ID O)

“

O) k_

®

0)

co ®

CO

CO

CO

CD

TO

c3

®

o

k_ z Q *

oS 3 D

CD CD

o CD CD

©

~o E E

CO E E

k_

CO

co co

o <3

>» >* >s

O o o

o o O O o

0) 0)0

• •* B»

• ® ® © 4-* 4—> 4_» CO © © *- k- k_

s 5 5

o o o

H- Hco co to

^

cm cm • «

>»

.2 ID

©

COO

OB (P/^P)

y31>!NlddS /

U313^Via 30l3ld0

y313^IVia NVICI3W 3NmOA

43

WEBER

NUMBER

(We)

Figure

29.

Experimental

verification

ofW

e

"

1/3

prediction
Flow

Cylindrical

Rate

Angle

1

1!

s

90°

o

o

0<3 O

O)

o>

CO CO

CM CM

o o o o o

o

GO

o

K

UJ o _|

CD 0

ID O

b

CD

o

CL

o 0

CO

o

CM

- O

-OB—ko

CM

O

OO

o

o

GO

O

o

CD

o

o

CM

(UJ7/) U313KIVICI NVICJ3W BKIfTlOA

44

Figure

30.

Volume

median

diemeter

vs.

position

angle
FORM NBS-1 14A (REV. 11 -84)

U.S. DEPT. OF COMM. 1. PUBLICATION OR 2. Performing Organ. Report No. 3. Publication Date

BIBLIOGRAPHIC DATA

REPORT NO. April 1988

SHEET (See instructions) NBSIR-88/3715

4. TITLE AND SUBTITLE

Measurement of Droplet Size in Sprinkler Sprays

5. AUTHOR(S)

J.R. Lawson, W.D. Walton, and D.D. Evans

6. PERFORMING ORGANIZATION (If joint or other than NBS, see in struction s) 7. Contract/Grant No.

NATIONAL BUREAU OF STANDARDS

U.S. DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

GAITHERSBURG, MD 20899

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

Swedish Fire Research Board n General Services Administration

and _ Stockholm,. Sweden Washington, DC

10.

SUPPLEMENTARY NOTES

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

11.

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

bi bl iography or literature survey, mention it here)

A computer-controlled video shadowgraph was used to collect data on' the spray

characteristics of a commercially available sprinkler head. A total of 15

tests were carried out that measured spray characteristics at different

positions close to the sprinkler head. Tests were conducted using two

different water flow rates, one and two liters per second. Droplet diameters

were measured and analyzed to produce graphic presentations of normalized

cumulative volume and cumulative number vs. droplet diameter data. In

addition, a comparison was made between the droplet diameters measured using

the video analyzer and droplet samples collected in a light oil and measured

manually using a microscope. The data are also compared with results found

in the literature. Data on more than 66,000 spray droplets were collected and

used for analysis in the development of this report.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) drop size measurements; droplets; water sprays; sprinkler heads; sprinkler

systems

13. AVAILABILITY 14. NO. OF

PRINTED PAGES

[jKj Uni i mi ted 51

~ For Official Distribution. Do Not Release to NTIS

Order From Superintendent of Documents, U.S. Government Printing Office, Washington, DC

20402. 15. Price

|~X] Order From National Technical Information Service (NTIS), Sptingfield, VA 22161 $13.95

USCOMM-DC 85-6006