flammability test data in risk assessment

THE ANNALS OF UNIVERSITY “DUNĂREA DE JOS“ OF GALAŢI
FASCICLE VIII, 2008 (XIV), ISSN 1221-4590
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Paper present at
Bucharest, Romania
FLAMMABILITY TEST DATA IN RISK ASSESSMENT
Lorena DELEANU 1) , Dragoş BUZOIANU 2) , Ştefan CRĂCIUNOIU 2) ,
Minodora RÎPĂ 1) , Constantin SPÂNU 1)
1) University Dunărea de Jos Galaţi, ROMANIA, 2) ICTCM, Bucharest, ROMANIA
lorena.deleanu@ugal.ro
ABSTRACT
This paper reviews the most recent information on standards dealing with testing
fire-resistance of hydraulic fluids in order to emphasis the importance of selecting
hydraulic fluids including as basic criteria of reducing fire risk in particular
and general industrial applications, gives information on an original stand for
determining the flammability characteristics of fire fluids in contact with hot surface
and presents preliminary results of the tests. These test results may be included in a
risk assessment in order to enhance the security and health levels in industry.
Keywords: flammability test, hydraulic fluid, risk assessment.
1. INTRODUCTION
Some relevant factors concerning hydraulic
fluid selection are: materials’ compatibility analysed
for the entire system, particular design requirements
(lubricating, sealing, cooling etc.), price of the selected
hydraulic fluids related to the price of the entire
system including maintenance and fire suppression
mechanisms, operating temperature range, lubrication
capacity, load capacity, operating pressure, maintenance
requirements, health, safety and environmental
requirements, fire-resistance [20, 43].
Selecting hydraulic fluids including as basic
criteria of reducing fire risk becomes of major interest
in particular and general industrial applications [3-5,
7, 16, 30, 34].
There are several reasons of fluid leaking:
- fatigue of system elements, under severe exploittation
conditions (cracks, creep etc.),
- hot metal increases its dimensions, bolts stretch; hot
fluid exhibits lower viscosity. In new and old systems,
frequent sources of leaks are flanges and hoses [1, 25],
- seals may become inefficient due to their property
changes produce by long exposure to temperature
or/and chemicals, but also by trapped solid particles;
- operator faults [1, 25]
- screwups: the tips come from actual case histories [22,
25]; a controlled mounting and operation decrease the
leak probability under functioning conditions. Also it is
important to respect procedures characterising the
opening and stopping of the equipment.
2. CURRENT STANDARDS ON FIRE-
RESISTANT HYDRAULIC FLUIDS
Table 1 presents the latest standards on testing
fire resistance of the hydraulic fluids including EN
ISO 20823: 2003 – Determination of the flammability
characteris-tics of fluids in contact with hot surfaces -
Manifold ignition test, EN ISO 2592:2001–Determination
of flash and fire points - Cleveland open cup
method, Approval Standard for Flammability Classification
of Industrial Fluids (Class 6930, 2002) [2],
Factory Mutual Global etc. and their relations to several
European Directives that include estimation of fire
resistance of the hydraulic fluids and safety for particular
industries (coal mine, metallurgical plants etc.).
Both manufacturers and users ask for tests that
certify fluid flammability characteristics, preferring
especially ISO or ASTM standards. Many documents,
including EU Directives, give recommendations to
use standard tests for estimating flammability characterisation
of fluids [2-4, 8, 11, 12, 14, 16, 17, 44].
The authors point out that the qualitative and
quantitative quantification of fire resistance of a
hydraulic fluid could not be done by one property only
and the different aspects of fire resistance have to be
outlined by different tests, including tests simulating on

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small scale the worst scenario that could happen in real
applications, when using hydraulic fluids [2-5, 16-19].
A particularity of many of these tests is that the test
result is delivered as “pass” or “not pass”. The fluids
that passed the tests are included in recommendations
or approvals, but these ones are specific to regional
reglementations (in SUA: Approval Guide or List of
Qualified Fluids, in European Union: [6, 7, 14, 16] or
in national normatives: [3, 13, 15]).
Organizations such as Occupational Safety and
Health Association (OSHA), National Fire Protection
Association (NFPA) and some specialists classify
flammable liquids according to their flashpoint [10,
33, 34, 39, 41]. A flashpoint within the operating
temperature range of the system obviously is
undesirable as any leak would create an immediate
fire hazard [20, 43].
The globalization of hydraulic fluid market
involved studies on existing and proposed fireresistance
and flammability tests in order that
manufacturers and users of such fluids have common
level of appreciating and comparing these products,
their applications and possible effects [11, 23].
Selling into multiple markets is very difficult if each
country or economic community has different
requirements and standards on using hydraulic fluids.
Many countries and firms subscribe to international
standards, but there are important economies as USA,
Japan ones that rely on their own standards, some of
them similar to international ones, other ones being
different. Users require that the products they buy
have to be certified according to standards applied in
their country. These have substantial financial
implications concerning expenses on laboratories and
test procedures, for both manufacturer and users [10,
40, 44]. The hydraulic fluid manufacturers have few
possibilities for complying this challenge: making
different products for different markets, making a
single product that passes multiple tests (taking into
account the potential of a cost disadvantage),
selecting only some of the potential markets
(international or domestic) accepting the risk of not
being a “global” producer.
The laboratories dealing with flammability and
fire-resistance properties have the advantage that
more tests implies more work, visibility and of
course, money but it also requires disadvantages as:
larger investment in equipment, a greater understandding
of similarities and differences among
related tests (including well-trained specialists),
agreements for cross-border acceptance of the
results [19, 20, 27].
The development of fire-resistant hydraulic
fluids required the identification of test methods that
could reproducibly differentiate the fire-resistance of
the fluids in a manner that would relate to real
industrial conditions [1, 25, 40]. Zinc elaborated a
classification of types of fire tests [44] according to
four elements (fig. 1):
- the fire resistant property that is being measured
as there are several different facets of fire resistance
and a test can measure one or more of them,
- the ignition source used in the test (almost all
fire resistance tests ignite or attempt to ignite the fluid
during the test),
- the state of the fluid during the test,
- whether the test simulates an accident condition
or measures an intrinsic property of the fluid.
Some tests are based on a simulated accident
(either explicitly or implicitly) while others measuring
an intrinsic property of the fluid are not based on
the conditions of any particular accident mode.
3. TESTS FOR DETERMINING THE
FLAMMABILITY CHARACTERISTICS OF
FLUIDS IN CONTACT WITH HOT
SURFACES
Specialists give information on testers and
methodologies that are related to flammability
characteristics of fluids on hot surfaces but the
methodologies and the procedures have a high degree
of differentiation [24, 26, 29, 35, 38, 41].
The standard SR EN ISO 20823:2004 “Ţiţei şi
produse înrudite. Determinarea caracteristicilor de
inflamabilitate a fluidelor în contact cu suprafeţe
calde. Încercarea de inflamabilitate pe metal cald” is
the national adoption by the endorsement method of
the standard EN ISO 20823:2003 Petroleum and
related products - Determination of the flammability
characteristics of fluids in contact with hot surfaces -
Manifold ignition test (ISO 20823:2003). This
standard gives a testing method for determining the
relative flammability of the fluids when the fluid
Fig. 1. Classification of fire tests.

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Table 1. Fire tests for hydraulic fluids.
Test Fluid state and ignition source / standards Measurements
flash point
Cleveland Open Cup Tester
Temperature value for flash point
[26, 36]
ISO 2592:2001, ASTM D92-05a, BS 4689:1980, IP 36
fire point
Cleveland Open Cup Tester
Temperature value for fire point
[10, 26]
ISO 2592:2001, ASTM D92-05a
open flame ignition
of a fluid spray
[28, 31, 42]
spark ignition of a
fluid spray [42]
hot surface ignition
of a fluid spray
[24, 29, 42]
open flame ignition
of bulk fluid [40]
flammability on hot
surfaces (plate or
manifold) [19, 39]
autoignition of fluid
ignition of fluid
soaked rags [2, 11]
ignition of fluid on
an absorbent
medium [16]
spray from 6.89MPa hollow cone nozzle – ISO 15029-1,
7 th LR 3.1.2, FM 6930:2002, RP55H * , ASTM D5306-
92(2002)e1
open flames may range from that equivalent to a match to
a blowtorch
Sparks energy in the range of 2mJ…2J
several types of sprays including that from ISO 15029-2,
7 th LR 3.1.3, RP55H *
flat hot plates with fixed temperatures up to 600°C, the
hot surface is moving through the fluid spray, varying
inclination and surface temperature.
a standard pool of fluid,
a fluid stream on an inclined plate, exposed to an open
flame; a range of open flame ignition sources
the fluid drops are fallen on a manifold heated
up to 700°C, i.e.: ISO 20823:2003
Federal Test Method 791, Method 6053.1.
the determination of hot- and cool-flame autoignition temperatures of a
liquid chemical in air at atmospheric pressure in a uniformly heated
vessel. i.e.: DIN 51794, ASTM E659-78(2005)
fluid-soaked mineral wool heated in an oven for an
extended period of time at a fixed temperature.
The test may provide pertinent information for safe
transportation and storage.
ISO 14935:1998, 7 th LR 3.1.3, RP66H * .
the heat release rate of the ignition
source
occurrence and position of any
ignition
linear flame propagation rate
the occurrence, energy and position of
any ignition within the spray
temperature of the hot plate measured
usually by infrared unit
ignition occurrence
observations of any ignition, time to
ignition and shape and position of the
flame
manifold temperature may be fixed up to 700°C
any noticed ignition, persistence of burn, flash
on, above or under the tube
autoignition
temperature **
bulk temperature, exposure time and
occurrence of any exothermal process are
monitored
assessment of the persistence of a flame
applied to the edge of a wick of nonflammable
material immersed in fireresistant
fluid.
7 th LR - 7 th Luxembourg Report
* All CETOP Technical Recommendations are no longer available for purchase from June 2002 and are officially
withdrawn but similar text might have been included in other official documents.
** This standard should be used to measure the properties of materials, products, or assemblies in response to heat and
flame under controlled laboratory conditions and should not be used to describe or appraise the fire hazard or fire risk of
these under actual fire conditions. However, results of this test may be used as elements of a fire risk assessment which takes
into account all of the factors which are pertinent to an assessment of the fire hazard of a particular use.
Table 2. Comparing two testing methods for testing fluid flammability on hot surfaces.
Manifold Ignition Test (Federal Test Method
791, Method 6053.1) [40],
EN ISO 20823:2003 Petroleum and related products -
Determination of the flammability characteristics of fluids in
contact with hot surfaces - Manifold ignition test
Test parameters
simulated manifold is heated at 700°C, temperature measured in
three points, fluid volume rate: 10 ml in 40...60 sec; fluid
temperature 20...25°C, dispenser tip at 300mm above the probably
impact point on the manifold,
sheet metal box 300 x 300 x 450 (mm)
Test evaluation
I(T), when the fluid flashes or burns on the tube but does not
continue to burn when collected in the tray below,
I(D), when the fluid flashes or burns on the tube and continues to
do so when collected in the tray below,
N when the fluid does not flash or burn at any time.
N when the fluid does not flash or bur nat any time.
simulated manifold is heated at 704°C (1300°F),
temperature measured at one point in the central
zone of the manifold, fluid volume rate: 10 ml in
40...60s
sheet metal box: 300 x 300 x 460 (mm)
a. flashes and burns on the manifold but not after
dripping from the manifold,
b. does not flash or burn on the manifold but does
after dripping from the manifold,
c. the fluid does not flash or burn on manifold or
after dripping from the manifold.
contacts a hot metallic surface having at fixed
temperature. The method also allows establishing the
ignition temperature of the studied fluid by varying
the manifold temperature.
The standard ISO 20823 was the subject of a
debate in the ISO/TC 28 [44]. The method appears
simply but it has not to be vague, so many comments
were done on expressing the principle, the method

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and the procedure. Even if the test is, in principle,
simple and the results are quantified in only three
possible ways, the procedure was well established in
order to obtain repeatability, a desired characteristic
of the test results but hard to obtain for test involving
fire or flammability characteristics [26]. Discussions
at ISO/TC 28 from 2000 also set the test parameters
accuracy, in order to give the possibility of ranking
fluids based on a well established procedure. For
instance, there was introduced three temperature
sensors, with imposed position on the manifold (two
on its opposite sides – near the ends of the rod and
one at the center of it), and not one as in the first
version of the standard, in order to have a better
control of the temperature uniformity that has to be at
all these three points within 700°C±5°C (or other
selected temperature, but with same accuracy)
Several specifications are related to the fluid
sample: the temperature, the volume and the state
(including the fact that “any air bubbles which may
have arise on mixing shall be allowed to escape from
the fluid before testing”). It is interesting to notice
that the majority of comments were done by countries
that are big manufac-turers and users of hydraulic
fluids (United Kingdom, Canada) [45].
This international test method and tester has the
highest degree of resemblance to the American Hot
Manifold Ignition Test (Federal Test Method 791,
Method 6053.1) [40], the results of the test being also
quantified in a similar way (Tab. 2). Even the tester
dimensions are very close to those of the tester
describes in EN ISO 20823:2003.
This ISO testing method is mainly used for
assessing the resistance to ignition of the fire-resistant
fluids that are, by definition, difficult to be ignited.
The procedure given in this standard is also specified
in ISO 12922-1999, Lubri-cants, industrial oils and
related products (class L). Family H (hydraulic
systems). Specifications for categories HFAE, HFAS,
HFB, HFC, HFDR and HFDU.
Many specifications related to hydraulic fluids
and oils include the results of some others tests
concerning the fire resistance and flammability, the
shear stability and the determination of extremepressure
and anti-wear properties, taking into account
other standards than those involved in this study [20,
21, 43]
The FM Standard 6930 [2] was intended to test
only hydraulic fluids. A sample of the hydraulic fluid
being tested was pressurized to 6.89MPa and heated
to a fixed temperature starting from 60°C. There were
performed four tests: test for determining the
chemical heat release rate of the fluid, flame
propagation test, test for measuring critical heat flux
for ignition, hot surface ignition test. The latest was
designed to mimic hydraulic fluid leaking under high
pressure from a hose in an environment where hot
surfaces are common. Hydraulic fluid was sprayed
from a nozzle onto a steel surface heated to 700°C.
FM will also work with the American Petroleum
Institute to include the new specification test
standard within a new hydraulic fluid flammability
standard being developed by the International
Organization for Standardization (ISO) [34].
The objectives of the grant CEEX-M4-452
includes applicative research concerning the three
testing methods that now are not performed in our
country for technical fluid assessment conformity by
taking into account the requirements of the European
directives [6-9, 14]. As far as the authors could have
investigated, the test included in SR EN ISO
20823:2004 has not been not performed in Romania
till nowadays. This affirmation is based on the
negative answers received from 10 laboratories
having RENAR (Asociatia de Acreditare din
Romania, Romanian Accreditation Association)
accreditation for analysing, testing and research on
fuels, oils, lubricants. These laboratories confirm that
they can not perform any one of the three tests under
the requirements of the European standards, as imposed
by the Directive 92/104 [7]. These laboratories
are: ICERP SA Ploieşti, ICMET Craiova, INCERP -
CERCETARE SA Ploieşti, LAREX CNIEP - Centrul
Naţional pentru Încercarea si Expertizarea Produselor,
ROMPETROL QUALITY CONTROL SRL,
PETROTEL LUKOIL SA Ploieşti, RULMENTUL
SA, PETROM SA (ARPECHIM).
Some laboratories explain the reasons why they
could not do these tests, especially the absence of the
necessary equipment and some of them could do one
or two of these tests but in accordance to other
standards. For instance, Total Lubrifin SA can
perform two of the above-mentioned tests but
following the requirements of ASTM standards.
4. THE TESTER
The tester design meets the requirements
imposed by SR EN ISO 20823:2004, comprising (fig.
2) a robotic system 1 that automatically ensures the
positioning of the fluid dispenser 5 above the
simulated manifold, at a position desired by the
operator, within a high temperature enclosure 4. The
manifold is made of corrosion resistant steel and it
could be heated by an electric system up to 700°C.
The temperature control is done by the help of three
digital thermocouples mounted on a transversal
guiding system 3 that allow them to be in contact
with the manifold and then withdrawn during the
fluid dropping. All the above mentioned subsystems
are enclosed in the ventilated enclosure 2.
5. PRELIMINARY RESULTS
Table 3 presents three tests done at elevated
temperature and in the last column there are presented
comments that could give supplementary
characteristics of the tested fluids. For instance, a

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characteristic that is not mentioned in ISO standard,
but was recorded during these preliminary tests, was
the time interval till the fluid starts to burn, time
measured from the starting of the fluid dispensing
process. From Table 3, one may notice that the grade
oil ACEA-2002 A2/B2 – API SL/CF had the largest
time interval between drop starting and burn starting
on the hot manifold. This larger time may be crucial
in activating the fire suppression systems. Another
important aspect noticed during these tests was the
quality and quantity of the residues left on the
manifold, in the tray and on the metal box walls.
Varying the manifold temperature and repeating
the test methodology it is possible to establish a temperature
(or a very narrow range of temperature) to
ignite the fluid, under the test conditions. This temperature
could be compared to the ignition point or flash
point, this comparison being a criterion for establishing
the degree of hazardous probability for the fluid.
Fig. 2. Tester for determining the flammability characteristics of fluids in contacts with hot surfaces.
Table 3 Preliminary results in determining the flammability characteristics of fluids in contacts with hot
surfaces (methodology as required by EN ISO 20823:2003) Average high 300± 10 mm, Oil volume 10±0.5 ml.
Number
Tested
oil of
test
Comments
Oil
grade
H.G. 46
Manifold
temperature
( o C)
Dropping
time
(sec)
1 620 45
2 620 45
3 620 45
1 700 50-60
Oil
grade
T 90
API
2 700 50-60
GL-2 3 700 o C 50-60
Oil grade
ACEA-
2002
A2/B2 –
API
SL/CF
1 700 o C 50-60
2 700 50-60
3 700 50-60
Permissible
deviation
of
parameters
±20 o C;
± 10 sec;
±20 o C;
± 10 sec;
±20 o C;
±0.5 ml;
± 10 sec;
- the fluid ignites after 5-7 sec and after dropping 1…1,5 ml of
fluid;
- test result: I(T), when the fluid flashes or burns on the tube
but does not continue to burn when collected in the tray below.
- the fluid ignites on the manifold after 5…10 sec of start dropping
and it burns in the tray below.
- test result: I(D), when the fluid flashes or burns on the tube
and continues to do so when collected in the tray below
- the fluid ignites and burns after 22 sec from drop starting; it burns
on the manifold, during its dripping but it does not burn in the tray,
- a lot of residue was noticed after burning on the tube but also on
the walls of the high-temperature metal enclosure,
- test result: I(D), when the fluid flashes or burns on the tube
and continues to do so when collected in thetray below

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a) The first fluid drops reach the manifold.
temperature at which the same fluid spray was not
ignited at least once. The conclusions of this study
reveal:
- the viscosity only seems to affect the oil
atomization, not the combustion,
- the flash point has little effect on the minimum
hot surface ignition temperature,
- hot surface ignition is affected both by
chemical reactivity and volatility of the fluid.
Babrauskas [41] assumed that the hot surface
ignition temperature is approximately 200°C above
the autoignition temperature, and future tests will try
to relate this characteristic to the temperature range
that passes one fluid from N category (when the fluid
does not flash or burn at any time) to I(T) or I(D)
categories.
6. USING TEST RESULTS IN RISK
ASSESSMENT
b) The first flashes, few seconds after starting the
fluid dropping.
c) The fluid burns on the manifold, during its drip and
it burns in the tray below.
Fig. 3. Images during the test.
Figure 3 presents images during the test done
for the fluid ACEA-2002 A2/B2 – API SL/CF.
A complex study [41] based on a simple
principle as that in ISO 20823, gave a range of hot
surface ignition temperatures for different fluids. The
test results are differently appreciated: the lower
value is the minimum hot surface temperature at
which the oil spray was not ignited at least once,
while the higher one is the maximum hot surface
There is no standard test which can reflect the
full range of hazard scenarios [2, 21, 32, 40, 44]. The
situation is complicated by the fact that, in industry,
there is no common understanding of the term „fireresistant”
and no universally accepted tests to
measure it. As a result fluids have been accepted as
„fire-resistant” and selected for safety critical end use
situations according to their performance in single
small scale tests of questionable scientific basis.
A engineer, working in either design or
maintenance department, has to do a selection of the
hydraulic fluids based on:
- information on the system that is designed or
under survey / maintenance,
- analysis of information and commentaries on
the similar situations that finished with fire accidents,
- a solid knowledge of hydraulic fluids and their
possible applications,
- a realistic risk assessment diagram [5] that
may indicate the test methods suitable for be
performed for fluid acceptance,
- the results of the selected tests.
The risk assessment is a scientifically based
process consisting of the following steps: hazard
identification, hazard characterization, exposure
assessment, and risk characterization. The risk, its
probability of occurring and possible damages it
could cause, vary depending on particularities of the
industrial and domes-tic applications. The risk
assessment is necessary for assuring an acceptable
level of security that differs due to the analysed
specific application [5, 11, 27, 32].
The difficulty in a risk assessment is the lack of
data for many inputs that has to be taken into account.
Results from laboratory tests have the potential to
solve, often only partially these problems but
specialists (both laboratory and risk assessment
experts) do not offer clear methods of how to use the
laboratory results [27].

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In a full risk assessment the evaluator has to do
a detailed examination of both technical system and
its environment and to perform a “full” inventory
(many accidents are the result of a “forgotten” aspect)
of potential ignition sources. This will include the
location and temperature of any hot surface, the
presence of lagged pipes or the existence of unsealed
electrical equipment etc. In normal functioning, if the
surface temperatures the fluid might contact, were
below the hot manifold ignition temperature (that
means for ISO 20823 the fluid is in N category), then
the source may be discounted in all but fault
conditions. Tribology could help specialists to
evaluate temperatures of different surfaces in relative
motion, in critical scenarios (leak of lubricant, plastic
deformations etc., total or partial removing of friction
coatings etc.). The evaluator may develop the
following scheme for ignition on hot surfaces:
- if normal functioning temperatures exceed the
test hot manifold temperature T c , the ignition
probability is 1,
- for functioning temperatures below T c , the
evaluator has to designate an ignition probability on a
scale that could be zero for some fraction from T c
(some specialists give 0.5T c or 0.75T c [27]),
- additional rising of ignition probability when
fault conditions are possible to happen.
In some cases the evaluator could apply risk
index methods, calculating a “risk value” or a risk
index, based on the relationship:
where
a j
= ∑ n
risk j ⋅ j
j=
1
I a r (1)
is the attribute j related to risk evaluation
(for instance, ignition temperature on hot surface,
smoke production, electrical ignition sources etc),
j=1...n, and is a value associated to probability of
r j
occurrence and consequences. Both
a j
and
r
j
have
to be introduced in a normalised scales. r j
may have
the following values: 0 – the occurrence is not
credible, 1 – unlikely, 2 – medium probability, 3 –
highly likely. For the attribute of ignition on hot
surfaces, the associated value could be related to
the ignition temperature of the fluid involved, but in
an indirect proportionality. For instance, if the
engineer had to select an industrial fluid among
several with different hot surface ignition
temperatures, T1〈 T 2...T
〈 n, after testing under the
procedure of ISO 20823, the fluid j has the
normalised attribute
a = T /T j (2)
j
It is obviously that a lower value of this
attribute is desired for safety functioning and for a
low probability of hazardous events. The problem to
be solved is the compromise between initial costs and
performances of the fluid to be selected. Several
decades ago the ratio between high security fluids and
n
r j
hazardous fluids was as great as 5...3 to 1. For
instance, a fluid-power system will be more
expensive when using water-based fluids due to the
materials involved in designing (especially corrosion
resistant steels, sealings etc.) as compared to a system
with similar performances but using mineral oils.
Recently, specialists give design solutions that
overpass only with 30...50% the classical ones that
use more hazardous fluids [20].
In mining industry potential sources of ignition
such as sparks, flames, electric arcs, high surface
temperatures, acoustic energy, optical radiation and
electro-magnetic waves have been identified in Directive
92/104/EEC [7] as being potentially present in underground
mines (the discharge of static electricity, stray
electric currents or discharges from malfunctioning
electricity supply equipment that could produce overheating
of surfaces or sparks capable of causing
ignition, friction between moving surfaces or the
entrapment of foreign bodies between moving
surfaces caused, for example, by failures of
mechanical plant, causing localised overheating, high
surface temperatures present in internal combustion
engines, braking systems, transmissions or exhausts,
the use of smoking or other materials that may be
contraband in some mines, existing fires caused by
ignition of other flammable materials in the mine).
Industrial development depends also on hydraulic
fluids, so their risk to fire has to be reduced by
different means: modifying their chemical
composition in order to shift temperatures related to
fire risk, mixing fluids in order to enlarge the
temperature range with no flammability or to reduce
fire risk, design solution for avoiding situations with
fire risk, a continuous training of operators, efficient
fire suppression systems.
The fire resistance of some hydraulic fluids may
change with time or with operational service. Fireresistant
fluids rely on their water content or their
chemical composition and physical properties to
provide fire resistance. Circumstances that could
result in the reduction of the water content below its
original value or chemical or physical changes in the
fluid could produce hard-to-estimate fire resistance.
Such situations could arise through persistent high
temperatures, fluid spillage where evaporation or
separation could occur, or breakdown of fluid
chemical properties during use. No specific test has
been designated to cater for these situations, which
should be addressed through regular fluid monitoring
and good maintenance procedures. The risk assessment
should assess the likelihood of the fire
resistance of a product being reduced in the application
for which it is intended. Other aspects such as
environmental requirements may have to be considered
and these may require additional or alternative
safety precautions to be employed [9, 32, 40, 43].
For reducing potential risks it is very important to
train employees on the risks associated with any
chemicals used at the operating site, the federal Right

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TRIBOLOGY
to Know laws (SUA) and several Directives of the
European Council [6-9, 14] require hazardous material
training for employees. However, the amount of
training provided to employees directly responsible for
hydraulic fluids is a decision left up to the plant
manager. They may not include all regulations, but will
provide some important limits.
The flammability on hot surfaces as a property
of technical fluids becomes more and more
investigated and related to actual applications, as this
event of fluid leaking on hot surfaces (if it is
happening) could lead to fire, self ignition and
explosion [1, 22, 25, 35, 37].
The European Union established serious and
ample reglementations for security and health
protection of workers, including the necessity of
having a realistic risk assessment done for the
particular industrial process [11]. An example is the
Council Directive 92/104/ EEC on the minimum
requirements for improving the safety and health
protection of workers in surface and underground
mineral-extracting industries (12th individual
Directive within the meaning of Art. 16(1) of
Directive 89/391/EEC) [7]. The enforced
requirements for hydraulic fluids are given in Part C
of the Annex of the Directive (Special minimum
requirements applicable to underground mineralextracting
industries) and are related to art. 11, Fires,
combustions and heatings.
BS EN 1050:1997 [5] also provides guidance
for the risk reduction.
Determination of what is “less hazardous” is
achieved by subjecting fluids to accepted tests, the
results of which give some quantitative measure of
their fire resistance. The importance of applying the
results of experience to the risk assessment procedure
cannot be over stressed. Substantial experience of the
safe use of fire-resistant fluids underground and in
other hazardous applications, and with the use of
other safety measures, is available [11, 25, 32, 33, 40].
The fluid suitability for a particular application
should be assessed in the light of experience of use in
the concerned equipment. The risk assessment should
therefore consider whether secondary safety
measures, in conjunction with, or instead of, certain
test requirements might be needed to provide a
satisfactory operational safety level. The level of fire
resistance of a fluid, i.e. the primary safety measure,
considered to be necessary, may depend on whether
secondary safety devices, e.g. fire extinguishers, are
in use at the site of application [11].
7. CONCLUSIONS
There is no test that ensures a high level of
safety for fire resistance but a particular set of tests,
selected after an actual risk assessment could give a
better solution for a system using hydraulic fluids in
high risk environments.
Determination of fluid flammability on hot
surfaces imposes particular solutions for improving
the security of the designed system.
Reducing fire risk is a matter of combining upto-date
information on fluids and design solutions for
using them, but also involves knowledge about
technological processes, work security. It has to be
analysed how close could be the test conditions to the
real ones. Large differences between these conditions
make the test information not only non-useful but
also dangerous because the results may be wrong
interpreted. Thus, they could lead to unsufficient
or/and unefficient measures for reducing or
eliminating potential ignition sources.
The list of hydraulic fluids possible to be
selected and the tests that these fluids have to pass,
will have to be known and set even in the designing
stage of the equipment in order to introduce necessary
solution for reducing fire risk. It is also important to
analyse similar accidents related to the real
applications in order to notice possible improvements
in equipment, process and environment control and
for workers’ training.
AKNOWLEDGEMENT
This research was supported by National
Authority for Scientific Research (ANCS), Minister
of Education and Research Romania, under the grant
CEEX-M4-452 “Adoption and Implementation of
Test Methods for Lubricant Conformity Assessment”.
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