Reference

i NBS

Publications A1110S L1A777

NBSIR 81-2373

An Evaluation of the MSHA

Temperature-Pressure Spray

Ignition Test for Hydraulic Fluids

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Center for Fire Research

Washington, DC 20234

September 1981

Final Report

Prepared for: U.S. Bureau of Mines

Pittsburgh, Pennsylvania 15213

and - - QC ie Safety and Health Administration

jjj idelphia. West Virginia 26059

. U56

81-2373

1981

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library

NOV ? 3 1981

NBSIR 81-2373

AN EVALUATION OF THE MSHA

TEMPERATURE-PRESSURE SPRAY

IGNITION TEST FOR HYDRAULIC FLUIDS

Joseph J. Loftus

Adalberto Maldonado-Rosado

Paula J. Allen

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Center for Fire Research

Washington, DC 20234

September 1981

Final Report

Prepared for: U.S. Bureau of Mines

Pittsburgh, Pennsylvania 15213

and

Mine Safety and Health Administration

Triadelphia, West Virginia 26059

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

NATIONAL BUREAU OF STANDARDS, Ernest Ambler. Director
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PREFACE

The alternate temperature pressure spray ignition test proposed

in this report, for measuring the flammability of hydraulic fluids

intended for use in underground coal mines, is intended to provide

for a simple quantitative measurement which can be used for quickly

rating or ranking fluids for flammability resistance. The method is

not proposed nor intended to provide for a standard measurement of

the properties of materials.
'

I
TABLE OF CONTENTS

Page

LIST OF FIGURES iv

LIST OF TABLES iv

Abstract 1

1. INTRODUCTION 1

2. TEST MATERIALS 2

3 . TEST METHOD 3

3.1 Apparatus 5 3.2 Test Procedure 7 3.3 Test Criteria 8

4. "MSHA TEST" - SPRAY IGNITION RESULTS 8

5. FLOW RATE CHARACTERIZATION 8 5.1 Calibration 10

5.2 Pressure Variations 12

5.2.1 Water 12

5.2.2 Hydraulic Fluids 12

6. ALTERNATIVE SPRAY IGNITION TESTS 16

6.1 Distance of Ignition Source 18

6.2 Nozzle Orifice Size 22

6.2.1 Pressure Variations 22

6.2.2 Temperature Variations 25

6.3 Test Results at 65°C and 150 psig 27

7. SUMMARY AND CONCLUSIONS 34

8. RECOMMENDATIONS 37

9. BIBLIOGRAPHY 38

iii
LIST OF FIGURES

Page

Figure 1. Spray ignition test apparatus 6

Figure 2. Effect of pressure on water spray 13

Figure 3. Effect of pressure on a hydraulic fluid 14

Figure 4. Thermopile for spray ignition test 19

Figure 5. Spray ignition test cabinet 20

Figure 6. Effect of distance (spray nozzle to ignition source) on

the flammability of hydraulic fluid spray 21

Figure 7. Relation of fluid temperature to flammability of invert

emulsion hydraulic fluids 28

Figure 8. Relation of fluid temperature to flammability of

synthetic hydraulic fluids . . 29

Figure 9. Relation of heat flux to exhaust temperature 32

LIST OF TABLES

Table 1. Viscosity of hydraulic fluids at various temperatures .... 4 Table 2. Results of MSHA spray ignition tests on hydraulic fluids . . 9

Table 3. Flowrate measurements for spray nozzles using water at

room temperature and 100 psig • 11

Table 4. Comparison of fluid flows - hydraulic fluids and water

sprayed at 65°C (150°F) and 150 psig 17

Table 5. Test nozzle orifices 23

Table 6. Relation of nozzle size and fluid pressure to stack

temperature rise 24

Table 7. Temperature rise values generated by the flaming fluid

sprays at various test temperatures 26

Table 8. Temperature rise and heat flux for hydraulic fluids at

65°C (150°F) and 150 psig pressure 30

Table 9. Comparison of spray ignition test results on hydraulic

fluids 33

IV
An Evaluation of the MSHA Temperature-Pressure

Spray Ignition Test for Hydraulic Fluids

Joseph J. Loftus, Adalberto Maldonado-Rosado and Paula J. Allen

Abstract

The Mine Safety and Health Administration

(MSHA) Temperature-Pressure Spray Ignition Test

for determining the fire resistance of hydraulic

fluids was evaluated in spray ignition tests on

14 different hydraulic fluids including water

glycols, synthetics, and invert emulsions.

Results of these and of other tests designed to

evaluate the test method and its procedures are

discussed in this report.

Key words: Hydraulic fluids; spray ignition;

fire resistance.

1. INTRODUCTION

At the request of the Mine Safety and Health Administration

(MSHA) and the Bureau of Mines (BOM) , the Center for Fire Research

at the National Bureau of Standards (NBS) evaluated the operational

1
characteristics of the fire test methods used by MSHA to qualify

hydraulic fluids as fire resistant and suitable for use in underground coal mines. There are three test methods described in the Code of Federal Regulations [l]"*" that an hydraulic fluid must meet

to be rated fire resistant. They are: (1) Autogenous ignition;

(2) Effect of evaporation on the flammability of hydraulic fluids;

(3) Temperature-pressure spray ignition.

This report is an evaluation of the Temperature-Pressure Spray

Ignition Test. The test equipment was assembled and standard tests were performed on 14 different hydraulic fluids. A calibration pro- cedure was developed for the system. Also, an alternative measure

of a fluid's flammability was developed to eliminate the subjective

nature of the present measurement.

2 . TEST MATERIALS

The 14 different hydraulic fluids used for the evaluation

tests included two water glycols, seven synthetics, and five invert

emulsions

.

Invert emulsions are fluids which consist of oil in a water

emulsion in which water is the continuous phase, and may vary

from 40 to 90 percent.

Numbers in brackets refer to the references at the end of this

report.

2
Synthetics are fluids which contain organic esters (e.g.,

phosphates) or synthetic hydrocarbons.

Water glycol fluids consist of a water glycol solution with

at least 35 percent water.

The fluids were obtained from manufacturers who normally

supply these materials to the underground coal mining industry

and who report that the fluids meet the flammability requirements

cited for hydraulic fluids in the above Code of Federal Regulations.

Table 1 lists specific gravity and viscosity measurements

(made by NBS ) for the fluids. At 20°C (8°F) the specific gravities

3 ranged from 0.91 to 1.15 g/cm and viscosities ranged from 38 to

417 centistokes. At 37.7°C (100°F) viscosities ranged from 21 to

168 centistokes and at 65°C (150°F) from 10 to 53 centistokes.

3. TEST METHOD

Virtually all the equipment used to mine or remove coal from

the working face is hydraulically operated. A rupture of the

hydraulic lines could release a high pressure fluid spray. If this spray were to encounter an ignition source, such as a hot surface

or a small open flame, it could produce flaming conditions that

would make fire a significant threat to the lives of the miners

3
Table 1. Viscosity of hydraulic fluids at various temperatures

Fluid

No. Type Specific Gravity Viscosity (Centistokes)

g/cm^ °C 20 38 65

1 Water Glycol 1.08 82 46 22

2 Water Glycol 1.06 83 52 23

3 Synthetic 0.99 191 94 32

4 Synthetic 1.14 263 88 24

5 Invert Emulsion 0.92 153 86 34

6 Synthetic 1.14 417 168 37

7 Invert Emulsion 0.94 120 76 25

8 Synthetic 1.20 38 21 10

9 Synthetic 1.13 144 54 18

10 Synthetic 1.15 95 45 15

11 Invert Emulsion 0.91 231 134 53

12 Synthetic 1.14 118 60 18

13 Invert Emulsion 0.93 290 130 52

14 Invert Emulsion 0.92 162 90 38

4
and cause damage to mining machinery. The Temperature-Pressure

Spray Ignition Test attempts to determine fluid fire performance

under simulated spray conditions.

In this test, hydraulic fluids at a temperature of 65°C

(150°F) and under a pressure of 1034 KPa (150 PSIG) are sprayed

(in separate tests) across each of three different ignition sources.

These are: (1) electric sparks; (2) a propane torch flame; (3) a flaming trough (made by igniting cotton gauze soaked in kerosene)

.

3.1 Apparatus

Figure 1 shows a schematic diagram of the Temperature-Pressure

Spray Ignition Test apparatus used in this evaluation. The system

consists of the following parts:

3 1. A 1000 cm (1 liter) capacity sample cylinder (fitted

with heating elements) to contain and heat fluids to testing

conditions

.

2. An atomizing round spray nozzle having a discharge orifice

of 0.64 mm (0.025 in) in diameter, reported by the manufacturer to

be capable of discharging 12.4 liters (3.28 gallons) of water per

hour with a spray angle of 90 degrees at a pressure of 689 KPa

(100 PSIG)

.

5
6

FIGURE

1

SPRAY

IGNITION

TEST

APPARATUS
3. A commercial pressurized cylinder containing nitrogen

with customary regulators, valves, tubing, and connectors to supply

nitrogen to the sample cylinder.

4. Additional apparatus includes a timer counter, programmable

timer, digital thermometer, temperature controller, pressure transducer, solenoid valve and two shielded chromel alumel thermocouples

to monitor fluid temperatures in the sample cylinder and at the spray

nozzle

.

3.2 Test Procedure

1. Test hydraulic fluid is added to the sample cylinder and

is heated to the test temperature of 65 + 5°C (150°F) .

2. The filled cylinder is pressurized to the testing pressure

of 1034 KPa (150 PSIG)

.

3. Fluid is sprayed (for up to 1 minute) into each of the

three different ignition devices held in the spray at a distance

of 45 cm (18 in) from the spray nozzle. [Note: Although not

specified in the Code of Federal Regulations, MSHA also conducts

tests at 60 and 90 cm (24 and 36 in) distances from the spray

nozzle .

]

4. A fluid is rated for flammability in accordance with

provisions of test outlined in 3.3 Test Criteria.

7
3.3 Test Criteria

A hydraulic fluid material meets the requirements of the

spray ignition test when visual observations show that it's spray

does not ignite or produce flaming for 6 continuous seconds or more

(when the ignition source is 45 cm (18 in) or more from the spray

nozzle) .

4. "MS HA TEST" - SPRAY IGNITION RESULTS

Table 2 lists the results of (CFR's) tests on 14 different

hydraulic fluids. Each spraying fluid was exposed to three different

ignition sources. Only one fluid (no. 10) , ignited when exposed to

electric sparks. (Note: Sparks were generated across a 1.25 cm (1/2

in) air space separating two copper electrodes.) The flaming cotton

and propane torch ignition sources produced identical results. Of

all the fluids tested, only three did not ignite from any exposure

two water glycols (nos. 1 and 2) and one synthetic (no. 3) . Certification based on tests at MSHA's Approval and Certification Center

on similar type fluids indicated that all these fluids were

acceptable by the above test procedure.

5. FLOW RATE CHARACTERIZATION

Because of the above noted disagreement (between MSHA and CFR)

in rating fluids for fire performance, the spray system's flow rate

was characterized. Initially, water was used to calibrate several

8
Table 2. Results of MSHA spray ignition tests on hydraulic fluids

Fluid Ignition Source

No. Type

Torch

(Benzomatic)

Electric

Sparks

Flaming

Cotton

1 Water Glycol N N N

2 Water Glycol N N N

3 Synthetic N N N

4 Synthetic I N I

5 Invert Emulsion I N I

6 Synthetic I N I

7 Invert Emulsion I N I

8 Synthetic I N I

9 Synthetic I N I

10 Synthetic I I I

11 Invert Emulsion I N I

12 Synthetic I N I

13 Invert Emulsion I N I

14 Invert Emulsion I N I

N - Nonignition

I = Ignition

9
nozzles. This was followed by a characterization of hydraulic

fluid flow rates through a stainless steel nozzle at the same

operating temperature of the test method but at different pressures.

5.1 Calibration

A simple, rapid procedure for calibrating the nozzle flow

rate was developed. The procedure requires that a preweighed

plastic bag be secured around the tip of the spray nozzle. The

plastic bag is sufficiently large to contain approximately 1 liter

of fluid. The spray system is activated and the fluid discharged

into the plastic bag for 1 minute. The volume of fluid discharged

and the rate of discharge can be calculated from fluid's specific

gravity and the weight of fluid collected in the plastic bag.

Using this procedure, six nozzles were calibrated. Three

were brass nozzles purchased by MSHA and three were stainless steel

nozzles obtained directly from the manufacturer. Table 3 lists

the flow rates obtained by discharging water through each nozzle.

The manufacturer rated these nozzles at (3.28 GPH) at a pressure of

689 KPa (100 PSIG) . The last column in table 3 shows the percent

difference between the measured flow rates and that claimed by the

manufacturer. The stainless steel nozzles showed a much smaller

difference in flow rate than the brass nozzles.

10
Table 3. Flowrate measurements for spray nozzles using

water at room temperature and 100 psig

% Difference

cc/min GPH From Expected*

Brass Nozzles

No. 1 234 3.71 +13

2 339 5.37 + 64

5 240 3.80 +16

Stainless Steel Nozzles

No. 1 222 3.52 + 7

2 203 3.22 - 2

3 224 3.55 + 8

Expected flow 3.28 GPH.

11
5.2 Pressure Variations

The effects of variations in pressure on the flow rate of

discharging fluid were studied to determine the precision with which

the pressure must be monitored. If small fluctuations in pressure

produced large fluctuations in the discharge rate, fire performance

in this test may vary and account for the observed discrepancies.

5.2.1 Water

The flow characteristics of a standard nozzle [Binks 0.64 mm

(0.025 in) diameter orifice] was determined by measuring the total

flow of water at 65°C (150°F) with delivery pressures ranging from

689 KPa (100 PSIG) to 6890 KPa (1000 PSIG) . Flow measurements were

made using the described procedure for nozzle flow rate calibration.

Figure 2 shows flow data for seven different pressures. Here the

total flow is plotted against the time of discharge. As expected,

the total flow increased linearly with increasing pressure. Water

discharge through the nozzle is about three times greater at 1000

PSIG than 100 PSIG.

5.2.2 Hydraulic Fluids

Total flow measurements for an invert emulsion fluid (no. 14)

at 65°C (150°F) and at six different pressures are shown in figure 3.

Compared to water flows (see figure 2) this fluid (and all other

12
350

(oo) mou

13

FIGURE

2.

EFFECT

OF

PRESSURE

ON

WATER

SPRAY
ALL

TEST

USE

SINKS

NOZZLE

F12-25

ORIFICE

.025"

o o o o o

o o o o o

CO LO CO OJ

(00) MOU

14

FIGURE

3.

EFFECT

OF

PRESSURE

ON

A

HYDRAULIC

FLUID
hydraulic fluids tested exceeded the water flow by values ranging

from 31 to 131 percent. Table 4 lists flow values for all 14 test

fluids and water when sprayed under test conditions.

An examination of this table shows that the general rank order

for decreasing fluid flows was invert emulsions, synthetic and

water glycol. All of the invert emulsions double the flow value

observed for water.

CONCLUSIONS - FLOW RATE CHARACTERIZATION

Flow rate characterization measurements were made to determine

if differences in flows might be responsible for differences found

between MSHA spray ignition test results (all 14 fluids were certified) and CFR's results (obtained using MSHA spray ignition test

procedures) where only three of the 14 fluids were rated as passing

fluid materials. Although the MSHA spray nozzle flow rates were

found to be higher (13-64%) than the nozzle manufacturer's reported

value of 3.28 GPH at 100 psig pressure (see table 3) and CFR's nozzle

flows were more closely aligned with the specified flow rates, it

would appear that these differences would not be large enough to

account for the differences in test results seen here.

CFR would thus attribute these differences to "operator

observations" (i.e., Did the fluid spray ignite and flame for 6 seconds continuously or not?). Quite possibly CFR was more critical of

test events than MSHA.

15
In order to avoid this qualitative method of obtaining test

results, CFR thus sought to develop a more objective (quantitative)

means of test whereby numbers (i.e., temperature and heat flux

values) would be used to rate or rank fluids for flammability

resistance. This alternate spray ignition test method would thus

essentially eliminate subjective interpretations of test results.

6. ALTERNATIVE SPRAY IGNITION TESTS

The new approach to spray ignition testing used the same

test apparatus and temperature-pressure testing conditions as specified in the MSHA spray ignition test. The new test provided

for measurement of heat (temperature rise) and energy (heat flux)

developed by flaming fluid materials which values would yield a more

quantitative measurement of flammability resistance. Numerical

values are thus obtained for exhaust gas temperature rise and heat

flux normal to the spray axis.

Temperature rise measurements are obtained with a thermopile

made of nine chromel-alumel thermocouples (0.64 mm diameter) connected

in parallel (see figure 4) . The thermopile is shown mounted in the

exhaust port of the test chamber (see figure 5)

.

16
Table 4. Comparison of fluid flows - hydraulic fluids and water

sprayed at 65°C (150°F) and 150 psig

Fluid No. Type Flow cc/min* % > Water

Water 214 0

8 Synthetic 280 31

9

If 318 49

1 Water Glycol 330 54

2

M 338 58

10 Synthetic 380 78

12 If 402 88

4

II 410 92

6

II 410 92

3

II 422 97

13 Invert Emulsion 434 103

11 II 442 106

7

ll 482 125

14 ll 486 127

5 Invert Emulsion 494 131

* Binks nozzle F-12-25 orifice 0.025 in used for test.

17
Heat flux measurements are made with a water cooled heat flux

transducer (Medtherm Corporation, Model No. 64-1-20) mounted in one

of the doors of the test chamber (see figure 5) and positioned to

look into and across developing flame fronts generated by flaming

fluid spray patterns.

The ignition source used for this spray test is the same as one of those used in the MSHA test; i.e., the flaming cotton or

trough test.

6.1 Distance of Ignition Source

Three different spray nozzle to ignition source distances

used by MSHA in their certification tests [45 cm (18 in) , 60 cm

(24 in), and 90 cm (36 in)] were evaluated by the CFR spray ignition

test. An invert emulsion fluid (no. 14) was used as the single test

fluid. Figure 6 shows a plot of temperature rise versus distance

for the test fluid. The data show that the stack temperature rise

was minimal for the 90 cm test. This was generally due to the fact

that the spray did not travel far enough to reach or become involved

with the ignition source. At 45 and 60 cm, the fluid sprays were

easily ignited and flamed considerably. The greatest degree of

flammability (highest temperature rise) was noted at the 45 cm

distance. An examination of these curves shows that after 10 seconds

of testing, the 45 cm distance (spray) had generated a temperature

rise of 270°C (518°F) while for the same time period the 60 cm

18
19

FIGURE

4.

THERMOPILE

FOR

SPRAY

IGNITION

TEST
20

*

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DEMINSIONS,

IN

CENTIMETERS
350

o ’03a 3aniva3dW3i

21

FIGURE

6.

EFFECT

OF

DISTANCESPRAY

NOZZLE

TO

IGNITION

SOURCE

ON

THE

FLAMMABILITY

OF

HYDRAULIC

FLUID

SPRAY
test spray produced a 120°C (248°F) of temperature rise. With the

ignition at the 90 cm test location the temperature rise was less

than 50°C even after 30 seconds of exposure.

6.2 Nozzle Orifice Size

Table 5 lists the spray nozzle type, spray angle, and orifice

diameter for five different nozzles used for tests described in

section 6.2.1.

6.2.1 Pressure Variations

Using an invert emulsion fluid (no. 14) as the test fluid and

a test temperature of 65°C (150°F) , stack temperature measurements

were for four different pressures ranging from 100 to 500 PSIG.

Results are listed in table 6.

An examination of this data shows that temperature rise and

temperature differences were slight for all size nozzles at 100 PSIG.

Negligible differences were also found for the .018 and .020 in

nozzles even at 150 and 300 PSIG pressures. The MSHA (.025 in) spray

nozzle produced the highest spray temperatures for all the nozzles

tested at pressures ranging from 150 (the MSHA test pressure) to

500 PSIG.

The 10 second temperature rise cut off point was arbitrarily

selected for two reasons (i.e.: safety and comparison of nozzle

performance) . To continue testing much beyond 10 seconds was

22
Table 5. Test nozzle orifices

Nozzle No. Type Spray Angle Orifice

1 Hollow Cone 70 .014

2 Hollow Cone 90 .018

3 Hollow Cone 70 .020

4 Round Spray 90 .025

5 Hollow Cone 70 .028

* Note: Nozzle diameter values are reported in terms of inches

by the nozzle manufacturers.

23
Table 6. Relation

to stack

of nozzle size and

temperature rise

fluid pressure

Nozzle No. 10 Sec Temperature Rise °C

in 100 psig 150 psig 300 psig 500 psig*

1 (.014) 52 56 176 206

2 ( .018) 47 43 48 106

3 ( .020) 55 54 60 164

4 (.025 ) 50 105 257 *

5 ( . 028) 71 102 142 326

* Flaming too severe to obtain a 10 sec reading.

NOTE: Nozzle diameter values in inches and pressure values in

psig are terms in common use by nozzle manufacturers.

24
judged unsafe and would have caused severe damage to test equipment.

In the case of the MS HA (.025 in) nozzle data for 10 seconds was

not obtained because of test severity.

As expected the quantity of fluid discharged (from the large

size nozzles) into the ignition source and its effect of flame

intensity was more pronounced at the higher fluid pressures

especially at 300 and 500 PSIG.

6.2.2. Temperature Variations

In the tests described here, the fluid temperature was varied

while the fluid pressure was held fixed at 150 PSIG.

Table 7 lists the spray nozzle type, spray angle, orifice

diameter, and the 10-second temperature rise values generated by

sprays for fluids at three different test temperatures.

Data show that a 30°C spread in fluid temperature (65 to 95°C)

did not appreciably affect the flammability of sprays from the smaller

size (0.014, 0.018, and 0.020 in diameter) spray nozzles. Temperature

rise values for these nozzles ranged from 41 to 61°C.

Temperatures generated by fluids sprayed from the larger size

nozzles (0.025 and 0.028 in diameter) showed that the 65°C fluid

produced values doubling those measured for the smaller size nozzles.

At fluid temperatures of 80 and 95 °C these temperature rise values

were higher by almost a factor of 3.

25
Table 7 . Temperature rise values generated by the flaming

fluid sprays at various test temperatures

Spray Nozzle 10 Sec Temperature Rise °C

Spray Fluid Test Temperature

Type Angle Orifice (in) 65° 00 O

o 95

Hollow Cone 70 .014 56 61 47

Hollow Cone 90 .018 43 53 41

Hollow Cone 70 .020 54 51 45

Round Spray* 90 .025 105 129 51

Hollow Cone 70 .028 102 184 162

* MS HA specified nozzle.

26
The highest temperature rise was recorded for fluid sprayed

from the 0.028 in diameter nozzle when the fluid temperature was

80°C.

Using the standard MSHA nozzle, figures 7 and 8 show the effect

of fluid temperature variation on stack temperature rise for invert

emulsion and synthetic fluids. In general, increasing the fluid's

starting temperature increases a fluid's flammability as measured

by stack temperature.

6.3 Test Results at 65°C and 150 PSIG

Table 8 lists the peak temperature rise and heat flux values

obtained for tests on hydraulic fluids using the CFR (alternate)

spray ignition test method. Tests were made under MSHA test conditions of fluid temperature at 65°C (150°F) and fluid pressure of

150 PSIG. Results show that the two water glycol fluids and one

synthetic resisted ignition and flaming in the tests, while all

five invert emulsions and six of the seven synthetic fluids did

ignite and flame vigorously. For safety reasons all tests were

terminated between 10 and 30 seconds.

Also listed in the table are 10-second temperature rise and

heat flux values for all of the test fluids. An examination of

these values shows that three invert emulsion fluids produced

27
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29
Table 8. Temperature rise and heat flux for hydraulic

fluids at 65°C (150°F) and 150 psig pressure

Fluid

2 No . Temperature Rise (°C) * Heat Flux Watts/Cm

10 Sec Peak 13-30 Sec 10 Sec Peak

1 Water Glycol 0 2 .02 .03

2 Water Glycol 5 8 .05 .05

3 Synthetic 3 12 .09 .15

4 Synthetic 6 53 .10 .38

5 Invert Emulsion 222 306 1.35 1.37

6 Synthetic 10 99 .16 .53

7 Invert Emulsion 34 129 .11 .43

8 Synthetic 140 158 .63 .70

9 Synthetic 70 204 .62 1.09

10 Synthetic 107 214 .82 1.19

11 Invert Emulsion 128 226 .51 .85

12 Synthetic 82 242 .71 1.09

13 Invert Emulsion 218 286 1.37 1.39

14 Invert Emulsion 216 296 1.37 1.48

* Temperature rise = peak temperature °C minus 30 °C.

30
temperature rise values greater than 200°C (392°F), while one

emulsion fluid and two synthetics showed temperatures greater than

100°C (212°F) in the initial 10-second time period.

The peak heat flux values, as expected, followed the same

rise patterns as were measured for temperature, e.g.: the lowest

values were recorded for the nonigniting water glycols and the

highest values were observed for the fluids which produced high

temperature rise values (296°C) . Maximum recorded values for

temperature rise and heat flux shown plotted in Figure 9 shows

good correlation between these parameters. This suggests that

either measurement could be used to characterize the flammability

of the hydraulic fluids tested.

A comparison of the MSHA method's spray ignition test results

with the Center's shown in Table 9 indicates that only three fluids

(nos. 1, 2 and 3), two water glycols and one synthetic, did not

ignite by MSHA standards. These fluids also performed well in the

Center's tests showing temperature rises ranging from 2°C to 12°C.

The main difference between the two test procedures is that the

Center's test generally gives quantitative information, by providing

for measurement of temperature rise and heat flux values generated

by flaming fluids. These numbers can be used to rate or rank

hydraulic fluids according to their fire resistance performance. The

MSHA test on the other hand only provides for a Pass/Fail concept

which in effect provides no information on the overall severity of

flaming exhibited by a burning fluid.

31
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32

TEMPERATURE

DEGREES

CENTIGRADE
Table 9. Comparison of spray ignition test results on hydraulic fluids

Fluid Number CFR Method MSHA Method

Temperature Rise (°C)*

10 seconds maximum

1 0 2 N

2 5 8 N

3 3 12 N

4 6 53 I

5 222 306 I

6 10 99 I

7 34 129 I

8 140 158 I

9 70 204 I

10 107 214 I

11 128 226 I

12 82 242 I

13 218 286 I

14 216 296 I

* Temperature rise = peak temperature °C minus 30 °C.

33
At the present time, no limits have been established for

temperature rise or heat flux values in the Center's spray

ignition test; however, it would appear that 10-second peak

temperature or heat flux values might serve as the base or limit

point for rating hydraulic fluids for fire resistance.

7. SUMMARY AND CONCLUSIONS

1. The Mine Safety and Health Administration (MSHA) Spray

Ignition Test (included in the Code of Federal Regulations Schedule

30 Part 35 Flammability Regulations for Hydraulic Fluids) was used

to determine the fire resistance of 14 different hydraulic fluids.

Two water glycol and one synthetic fluid met all the requirements

of the MSHA test while the remaining fluids failed to meet the test

criteria.

2. Electric sparks as an ignition source (in the MSHA test)

were unable to ignite 13 of the 14 test fluids.

3. The exact duplication of results obtained for propane

torch and flaming cotton (trough) tests in the MSHA tests questions

the need for two flame ignition sources in the MSHA test method.

4. A procedure was developed for calibrating spray nozzles for

flow rates. By this method, nozzles which operate within + 10 percent

of the nozzle manufacturer's stated flow rate might be specified in

the test method.

34
5. Test hydraulic fluids discharged at a faster rate than

water in the spray test setup. At the specified test temperature

of 65°C (150°F) and pressure of 150 PSIG, the decreasing order of

flow rates by fluid type was invert emulsion, synthetic, water

glycol, and water. On a percent basis the hydraulic fluid flow

rates were 31-131 percent greater than for water.

6. A quantitative spray test concept for determining the fire

resistance of hydraulic fluids was developed by the Center for Fire

Research at the National Bureau of Standards (NBS) . The method uses

temperature rise and heat flux measurements to rate or rank fluids

for flammability based on their performance in the test.

7. Evaluations of the distances between the spray nozzle and

the ignition source, e.g., 45, 60, and 90 cm, in spray ignition

tests showed that the "worst case conditions" or highest temperature

rise values were obtained for fluids sprayed at a distance of 45 cm

(18 in) from the ignition source. The distance specified for the

MSHA test is 45 cm.

8. The effect of varying parameters on the fire performance

of hydraulic fluids showed that flame intensity increased with

nozzle pressure and short nozzle to ignition source distance.

9. A study of the relation of hydraulic fluid temperature

to flammability showed in the Center's spray ignition tests that

flaming intensity (for all fluid sprays except water glycols)

increased with increasing fluid temperatures.

35
10. A comparison of MSHA test results with stack temperature

rise values obtained in the Center's tests showed that a criterion

of a maximum acceptable stack temperature of 50°C produced excellent

agreement between the two tests (shown in table 9)

.

11. The combined effect of spray nozzle orifice size and

varying fluid pressures on flammability showed that at 100 PSIG

pressure the size of the spray nozzle orifice was not critical to

temperature rise; however, at 150 PSIG the temperature rise generated

by sprays from the large size nozzles (0.025 and 0.028 in) was almost

double the temperature values measured for fluid sprayed from the

smaller size nozzles (0.014, 0.018, and 0.020 in). At 300 PSIG

sprays from the MSHA nozzle (0.025 in) produced the highest temperature

rise value, 257°C, and at 500 PSIG the spray from the MSHA nozzle

flamed so severely that a 10-second reading could not be attempted.

For safety reasons the MSHA specified pressure of 150 PSIG appears

adequate for making spray test measurements.

12. The combined effect of spray nozzle orifice size and

varying fluid temperatures on flammability showed that sprays from

the small size nozzles (0.014, 0.018, and 0.020 in) produced only

slight differences in temperature rise for the test fluid sprayed

at temperatures of 65, 80, and 95°C.

The larger size nozzles (0.025 and 0.028 in), as expected,

allowed more fluid (or fuel) to become involved with the ignition

36
source and thus temperature rise values increased by at least a

factor of three over values recorded for smaller size nozzles.

8 . RECOMMENDATIONS

Based on the results of this evaluation study, the following

recommendations can be made:

1. The MSHA Temperature-Pressure Spray Ignition Test conditions

i.e., 150 PSIG pressure, 65°C (150°F) temperature, spray nozzle

orifice size of 0.025 in diameter and distance—spray nozzle to ignition source of 45 cm, all appear to be ideal for conducting spray

ignition tests on hydraulic fluids.

2. The flaming cotton test should be used as the sole ignition

source for the MSHA spray ignition test because it represents the

most severe (or worst case) condition and is safer to conduct

than the propane torch test when the torch must be moved in the

fluid spray.

3. The main problem or difficulty found with the MSHA spray

ignition test method is in the interpretation of test results (i.e.,

in making decisions as to whether a test fluid flamed for six continuous seconds or not) . Since this pass-fail judgement is qualitative and is left to the test operator it sometimes occurs that

different viewers of the same test may reach opposite conclusions.

37
Under such circumstances it is not unexpected that reproducibility

of the test among different laboratories may indeed be poor. It is

recommended that the present criterion be changed to a maximum

temperature rise criterion and that this procedure be developed

further and completely evaluated.

9. BIBLIOGRAPHY

[1] Code of Federal Regulations Schedule 30 Part 35 for Measuring

the Flammability of Hydraulic Fluids.

[2] NBSIR-81-2247 Flammability Measurements on Fourteen Different

Hydraulic Fluids Using a Temperature Pressure Spray Ignition

Test.

38
NBS-114A (rev. 2 -eo) U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR 81-2373

2. Performing Organ. Report No 3. Publication Date October 1981

4. TITLE AND SUBTITLE

AN EVALUATION OF THE MSHA TEMPERATURE-PRESSURE SPRAY IGNITION TEST FOR HYDRAULIC

FLUIDS

5. AUTHOR(S)

Joseph J. Loftus, Adalberto Maldonado-Rosado, and Paula J. Allen

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)

U.S. Bureau of Mines

Pittsburgh, Pennsylvania 15213

Mine Safety and Health Administration

and Triadelphia, West Virginia 26059

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)

The Mine Safety and Health Administration (MSHA) Temperature-Pressure Spray Ignition

Test for determining the fire resistance of hydraulic fluids was evaluated in spray

ignition tests on 14 different hydraulic fluids including water glycols, synthetics,

and invert emulsions. Results of these and of other tests designed to evaluate the

test method and its procedures are discussed in this report.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) Coal mine; fire tests; hydraulic fluids; invert emulsions; pressure-temperature;

spray; synthetics; water glycol.

13. AVAILABILITY

[jq|[ Unlimited

| | For Official Distribution. Do Not Release to NTIS

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

20402.

[X2£. Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

44

15. Price

$6.50

USCOMM-DC 6043-P80