THE ASSEMBLY,
RECALLING Article 15(j) of the Convention on the
International Maritime Organization concerning the functions of the Assembly in relation
to regulations and guidelines concerning maritime safety,
RECALLING FURTHER that it adopted, by resolution A.564(14), the Revised
Recommendation on Fire Test Procedures for Surface Flammability of Bulkhead, Ceiling and
Deck Finish Materials, with reference to the term "low flame spread" in regulations
II-2/3.8, II-2/34.3 and II-2/49.1 of the International Convention for the Safety of Life
at Sea, 1974, as amended,
RECOGNIZING the need to
improve these test procedures in the light of experience gained,
HAVING CONSIDERED the recommendation made by the Maritime Safety
Committee at its fifty-seventh session,
1.
ADOPTS the Recommendation on Improved Fire Test Procedures for Surface Flammability of
Bulkhead, Ceiling and Deck Finish Materials, the text of which is annexed to the present
resolution and which supersedes the Revised Recommendation annexed to resolution
A.564(14);
2. RECOMMENDS Governments
concerned to apply the Recommendation on Improved Fire Test Procedures set out in the
Annex, in lieu of the Revised Recommendation as annexed to resolution A.564(14) in
conjunction with the guidelines on the evaluation of fire hazard properties of materials
set out in resolution A.166(ES.IV).
Annex Recommendation on improved fire test procedures for surface flammability of bulkhead, ceiling and deck finish materials
01 Scope
This Recommendation specifies a procedure for measuring fire
characteristics of bulkhead, ceiling and deck finish materials as a basis for
characterizing their flammability and thus their suitability for use in marine
construction.
02 Warning
2.1 Ignition hazards
The use of this test method involves the generation of very high
heat flux levels which are capable of causing ignition of some materials such as
clothing following even brief exposures. Precautions should be taken to avoid
accidental ignitions of this type.
2.2 Toxic
fume hazards
The attention of the user of this test is drawn to the fact that
the fumes from burning materials often include carbon monoxide. Other more toxic
products may in many instances be produced. Suitable precautions should be taken to
avoid any extended exposure to these fumes.
03 Definitions
Certain terms used in this Recommendation require definition
for clarity. Other fire characteristic terms are also used; these are defined
hereunder but relate only to the results of measurements by this specific test
method.
3.1 Compensating thermocouple
A thermocouple for the purpose of generating an electrical signal
representing long-term changes in stack metal temperatures. A fraction of the signal
generated is subtracted from the signal developed by the stack gas thermocouples.
3.2 Critical flux at extinguishment
A flux level at the specimen surface corresponding to the distance
of farthest advance and subsequent self-extinguishment of the flame on the
centreline of a burning specimen. The flux reported is based on calibration tests
with a dummy specimen.
3.3 Dummy specimen
A specimen used for standardizing the operating condition of the
equipment; it should be roughly 20mm thickness, 800± 100 kg/m3 density
and should meet the requirements of resolution A.472(XII) as non-combustible.
3.4 Special calibration dummy specimen
A dummy specimen as defined by figure 14 intended only for use in
calibration of heat flux gradient along with specimen.
3.5 Fume stack
A box-like duct with thermocouples and baffles through which
flames and hot fumes from a burning specimen pass. Its purpose is to permit
measurement of the heat release from the burning specimen.
3.6 Heat for ignition
The product of the time from initial specimen exposure until the
flame front reaches the 150mm position and the flux level at this position; this
latter obtained in prior calibration of the apparatus. 3.7 Heat release of specimen
The observed heat release under the variable flux field imposed on the specimen and
measured as defined by the test method.
3.8
Heat for sustained burning
The product of time from initial specimen exposure until arrival
of the flame front and the incident flux level at that same location as measured
with a dummy specimen during calibration. The longest time used in this calculation
should correspond to flame arrival at a station at least 30 mm prior to the position
of furthest flame propagation on the centreline of the specimen.
3.9 Reverberatory wires
A wire mesh located in front of, but close to, the radiating
surface of the panel heat source. This serves to enhance the combustion efficiency
and increase the radiance of the panel.
3.10
Viewing rakes
A set of bars with wires spaced at 50mm intervals for the purpose
of increasing the precision of timing flame front progress along the
specimen.
04 Principle of the test
This test provides methods for evaluating flammability
characteristics of 155mm × 800mm specimens in vertical orientation. The specimens
are exposed to a graded radiant flux field supplied by a gas-fired radiant panel.
Means are provided for observing the times to ignition, spread and extinguishment of
flame along the length of the specimen as well as for measuring the compensated
millivolt signal of the stack gas thermocouples as the burning progresses.
Experimental results are reported in terms of: heat for ignition, heat for sustained
burning, critical flux at extinguishment and heat release of specimen during
burning.
05 General
A detailed description of the facility and apparatus required
for conduct of this test is included in the appendix. Compliance with the appendix
forms an essential requirement of the test method. The equipment needed may be
summarized as follows:
5.1.1 Special test
room fitted with fume exhaust system as well as fresh air inlet.
5.1.2 Radiant panel frame fitted with blower or other
source of combustion air, a methane* or natural gas supply system with suitable
safety controls, and a radiant panel heat source, with reverberatory wires, arranged
to radiate on a vertical specimen. Alternatively, an electrically heated radiant
source of the same dimensions may be used provided it can expose the specimen to the
heat flux distribution shown in table 1. The effective source temperature of any
radiant panel is not greater than 1,000°C.
5.1.3 The specimen holder frame, three specimen holders, two parts of
pilot burners, specimen holder guides, viewing rakes and a viewing mirror.
5.1.4 A specimen fume stack with both stack
gas and stack temperature compensating thermocouples together with a means for
adjusting the magnitude of the compensation signal.
5.1.5 Instrumentation comprising a chronograph, digital or
sweep second electric clock, a digital millivoltmeter, a two-channel millivolt
recorder, gas-flowmeter, heat-fluxmeters, a wide angle total radiation pyrometer and
a stopwatch. Use of a data acquisition system to record both panel radiance and the
heat release stack signal during test will facilitate data reduction.
The use of gases other than methane or natural gas is not
recommended although with changes in panel-specimen spacing it has been reported
possible to use the equipment with propane up to flux levels of 50
kw/m2. 06 Calibration
Mechanical, electrical and thermal calibrations should be
performed as described in the appendix. These adjustments and calibrations should be
performed following initial installation of the apparatus and at other times as the
need arises.
6.1 Monthly verification
The calibration of the flux distribution on the specimen and the
proper operation of the fume stack with its thermocouple system should be confirmed
by monthly tests, or at more frequent intervals if this is found necessary (see
4.3.1 and 4.6 in the appendix).
6.2 Daily
verification
As a means of assuring continued proper adjustment of the
apparatus, the following tests should be performed on a daily basis, or more
frequently if the nature of the specimens makes this necessary.
6.2.1 Adjustment of the pilot burner, the acetylene and
air supply should be adjusted to provide a flame length of about 230mm*. When this
has been done, the flame length as viewed in a darkened laboratory will be seen to
extend about 40mm above the upper retaining flange of the specimen holder. The
burner spacing from the specimen is adjusted while the radiant source is operating
by the use of softwood splines of 3mm thickness and of 10mm and 12mm width. When
these splines are moved during a two second exposure along the flame length, between
the pilot burner flame and a dummy specimen surface, the 10mm spline should not be
charred but the 12mm spline should show char. With the specimen in the vertical
position, the charring of the 12mm spline should occur over a vertical distance of
at least 40mm from the upper exposed edge of the specimen (see figure 9 in the
appendix). 6.2.2 The stack gas thermocouples should be cleaned by light brushing at
least daily. This cleaning may be required even more frequently, in some instances
before each test, when materials producing heavy soot clouds are tested. These
thermocouples should also be individually checked for electrical continuity to
ensure the existence of a useful thermojunction. Following daily cleaning of the
parallel connected stack gas thermocouples, both they and the compensating junction
should be checked to verify that the resistance between them and the stack is in
excess of 106 ohms. 6.3 Continuous monitoring of operation A dummy
specimen should remain mounted in the position normally occupied by a specimen
whenever the equipment is in stand-by operation. This is a necessary condition of
the continuous monitoring procedure which is accomplished by measuring: .1 the
millivolt signals from both the stack thermocouples and the total radiation
pyrometer mounted securely on the specimen holder frame facing the surface of the
radiant panel; or .2 the millivolt signals from both the stack thermocouples and a
heat-fluxmeter positioned at 350mm from the exposed hot end of a marine board
specimen of about 20mm thickness (see appendix, paragraph 4.3.2). Either of these
measurement methods would be satisfactory for determining that an appropriate
thermal operating level has been achieved. The use of the radiation pyrometer is
preferable since it permits continuous monitoring of panel operating level even when
tests are in progress. Both signals should remain essentially constant for three
minutes prior to the test. The observed operating level of either the radiation
pyrometer or the fluxmeter should correspond, within 2%, to the similar required
level specified in table 1 and referred to in the calibration procedure mentioned in
6.1 above.
* It is recommended that, to give increased precision, acetylene
rather than other gases be used wherever possible. 07 Specimens
7.1 Number required
Three specimens should be tested for each different exposed
surface of the product evaluated and applied.
7.2 Dimensions
The specimens should be
wide by
long, and should be representative of the product.
7.2.1 Specimen thickness: materials and
composites of normal thickness 50mm or less should be tested using their full
thickness, attaching them, by means of an adhesive if appropriate, to the substrate
to which they will be attached in practice. For materials and composites of normal
thickness greater than 50mm, the required specimens should be obtained by cutting
away the unexposed face to reduce the thickness to
7.3 Composites
Assembly should be as specified in 7.2. However, where thin
materials or composites are used in the fabrication of an assembly, the presence of
an air gap and/or the nature of any underlying construction may significantly affect
the flammability characteristics of the exposed surface. The influence of the
underlying layers should be recognized and care taken to ensure that the test result
obtained on any assembly is relevant to its use in practice.
7.4 Metallic facings
If a bright metallic faced specimen is to be tested, it should be
painted with a thin coat of flat black paint prior to conditioning for test.
7.5 Marking specimens
A line should be marked centrally down the length of the tested
face of each specimen. Caution should be exercised to avoid the use of a line which
would influence specimen performance.
7.6 Conditioning of
specimens
Before test, the specimens should be conditioned
to constant moisture content, at a temperature of 23± 2°C, and a relative
humidity of 50± 10%. Constant moisture content is considered to be reached when,
following two successive weighing operations, carried out at an interval of 24
hours, the measured masses do not differ by more than 0.1% of the mass of the
specimen.
08 Test Procedure
8.1 General considerations
The test method involves mounting the conditioned specimen in a
well-defined flux field and measuring the time of ignition, spread of flame, its
final extinguishment together with a stack thermocouple signal as an indication of
heat release by the specimen during burning.
8.1.1 Prepare a properly conditioned specimen for test in a cool holder
away from the heat of the radiant panel. Prior to insertion in the specimen holder,
the back and edges of the specimen should be wrapped in a single sheet of aluminium
foil of 0.02mm thickness and dimensions of (175 + a)mm × (820 + a)mm where "a" is
twice the specimen thickness. When inserted in the specimen holder each specimen
should be backed by a cool 10 ± 2mm board of non-combustible refractory insulating
material with the same lateral dimensions and density as the dummy specimen. When
mounting non-rigid specimens in the holder, shims should be placed between specimen
and holder flange to ensure that the exposed specimen face remains at the same
distance from the pilot flame as a rigid specimen. For such materials, the shims may
often only be required for a 100mm length at the hot end of the specimen.
8.1.2 The dummy specimen in a specimen
holder should be mounted in position facing the radiant panel. The equipment fume
exhaust system should be started.
8.1.3
The radiant panel is operated to realize the test conditions as specified in 6.3.
Start the millivolt recorder recording the output signal of the stack thermocouples,
as well as signal from the total radiation pyrometer or heat-fluxmeter positioned,
as described in 6.3.2.
8.1.4 When the
radiant panel and stack signals have attained equilibrium, after the preheat period,
light the pilot flame, adjust its fuel flow rate and observe both signals for at
least three minutes and verify continued signal stability.
8.1.5 After both signals reach stable levels, remove the
dummy specimen holder and insert the specimen in the test position within 10 s.
Immediately start both the clock and chronograph.
8.1.6 Operate the event marker of the chronograph to indicate the time of
ignition and arrival of the flame front during the initial rapid involvement of the
specimen. The arrival at a given position should be observed as the time at which
the flame front at the longitudinal centreline of the specimen is observed to
coincide with the position of two corresponding wires of the viewing rakes. These
times are recorded manually both from measurement on the chronograph chart and from
observations of the clock. As far as possible, the arrival of the flame front at
each 50mm position along the specimen should be recorded. Record both the time and
the position on the specimen at which the progress of flaming combustion ceases. The
panel operating level, as well as stack signals, should be recorded throughout the
test and continued until test termination.
8.1.7 Throughout the conduct of the test, no change should be made in the
fuel supply rate to the radiant panel to compensate for variations in its operating
level.
8.2 Duration of test The test
should be terminated, the specimen removed, and the dummy specimen in its holder
reinserted when any one of the following is applicable: .1 the
specimen fails to ignite after a 10 min exposure; .2 3 min have
passed since all flaming from the specimen ceased; .3 flaming
reaches the end of the specimen or self-extinguishes and thus ceases progress
along the specimen. This criterion should only be used when heat release
measurements are not being made.
8.2.1
Operations 8.1.1 to 8.1.7 should be repeated for two additional specimens
(see 8.3).
8.3 Conditions of retest
In the event of failure, during test of one or more specimens, to secure
complete flame spread times or a reasonable heat release curve, the data secured
should be rejected and a new test or tests performed. Such failures might
involve, but not be limited to, incomplete observational data or malfunction of
data logging equipment. Excessive stack signal baseline drift should also
require further equipment stabilization and retest.
8.3.1 In the event that the first two or three specimens
do not ignite following exposure for 10 min, at least one specimen should be
tested with the pilot flame angled to impinge on the upper half of the specimen.
If this specimen ignites, two additional tests should be run under the same
conditions.
8.3.2 If a specimen shows
extensive loss of incompletely burned material during test, at least one
additional specimen, restrained in the testing frame by poultry netting, should
be tested and the data secured reported separately.
8.4 Observations In addition to the recording of the
experimental data, observations should be made and recorded on general behaviour
of the specimen including: glowing, charring, melting, flaming drips,
disintegration of the specimen, etc.
09 Derived fire characteristics
Experimental results should be reported in terms of the
thermal measurements of incident flux measured with a dummy specimen in place. The
results should not be adjusted to compensate for changes in the thermal output of
the radiant panel during the conduct of the test. The following data should be
derived from the test results.
9.1 Heat for
ignition
As defined in 3.6.
9.2 Heat
for sustained burning
A list of the values of this characteristic as defined in
paragraph 3.8.
9.3 Average heat for sustained
burning
An average of the values for the characteristic defined in 3.8
measured at different stations, the first at 150mm and then at subsequent stations
at 50mm intervals through the final station or the 400 mm station, whichever value
is the lower.
9.4 Critical flux at
extinguishment
A list of the values of this characteristic for the specimens
tested and the average of these values.
9.5
Heat release of the specimen
Both a heat release time curve and a listing of the peak and total
integrated heat release should be secured from the experimental data. They should be
corrected for the non-linearity of the heat release calibration curve. The curve of
the millivolt signal from the stack thermocouples should include at least 30 s of
the initial 3 min steady state verification period as well as the starting transient
just prior to and following specimen insertion. In converting millivolt signals to
heat release rate, the zero release level of the calibration curve should be set at
the level of the initial steady state just prior to test of the specimen involved.
See figure 13.
9.5.1 Total heat release
The total heat release is given by integration of the positive
part of the heat release rate during the test period (see figure 13).
9.5.2 Peak heat release rate
The peak heat release rate is the maximum of the heat release rate
during the test period (see figure 13).
10 Classification
Materials giving average values for all of the surface
flammability criteria not exceeding those listed in the following table, are
considered to meet the requirement for low flame spread in compliance with
regulations II-2/3.8, II-2/34 and II-2/49 of the International Convention for the
Safety of Life at Sea, 1974, as amended.
11 Test Report
The test report should include both the original data,
observations made on each specimen tested and the derived fire characteristics. The
following information should be supplied:
- Name and address of testing
laboratory.
- Name and address of sponsor.
- Name and address of
manufacturer/supplier.
- Full description of the product tested including
trade name, together with its construction, orientation, thickness, density and,
where appropriate, the face subjected to test. In the case of specimens which
have been painted or varnished, the information recorded should include the
quantity and number of coats applied, as well as the nature of the supporting
materials.
- Data from the test including: .5.1 number of
specimens tested; .5.2 type of pilot flame used; .5.3
duration of each test; .5.4 observations recorded in accordance
with 8 above; .5.5 other relevant observations from the test, such
as flashing, unstable flame front, whether or not pieces of burning
materials fall off, separations, fissures, sparks, fusion, changes in form;
.5.6 derived fire characteristics as described in 9 above;
.5.7 classification of the material.
- A limiting
use statement.
Note: The test results relate only to the behaviour of the test specimens of a
product under the particular conditions of the test; they are not intended to be
the sole criterion for assessing the potential fire hazard of the product in
use.
Appendix
This appendix provides technical information intended to permit
construction, erection, alignment and calibration of the physical equipment required
for the conduct of tests by this procedure.
1 Test equipment fabrication
Figures 1 to 5 show photographs of the equipment as assembled
ready for test. Detailed drawings and a parts list are available from the IMO
Secretariat. These provide engineering information necessary for the fabrication of
the main frame, specimen holders, stack and other necessary parts of the equipment.
1.1 Brief parts list for the test
equipment assembly includes:
- The main frame (figure 1) which comprises two
separate sections, the burner frame and the specimen support frame. These two
units are bolted together with threaded rods permitting flexibility in
mechanical alignment.
- Specimen holders which provide for support of the
specimens during test. At least two of these are required. Three prevent delays
resulting from required cooling of holders prior to mounting specimens.
- A specimen fume stack fabricated of stainless steel sheet of 0.5±
0.05mm thickness complete with gas and stack metal compensating thermocouples.
- The radiant panel which has radiating surface dimensions of 280mm x
483mm. It has been specially fabricated for use with this equipment through use
of commercially available porous refractory tiles.
- The blower for
combustion air supply, radiant panel, air flow metering device, gas control
valves, pressure reducer and safety controls which are all mounted on the burner
frame (figure 3). Requirements are summarized below:
- Air supply of about
30m3/h at a pressure sufficient to overcome the friction losses
through the line, metering device and radiant panel. The radiant panel drop
amounts to only a few millimetres of water.
- The gas used may be
either natural gas or methane. The use of gas other than methane or natural
gas is not recommended*, although with changes in panel-specimen spacing, it
is possible to use the equipment with propane at flux levels of 50
kW/m2. A pressure regulator should be provided to maintain a
constant supply pressure. Gas is controlled by a manually adjusted needle
valve. No venturi mixer is necessary. Safety devices include an electrically
operated shutoff valve to prevent gas flow in the event of electric power
failure, air pressure failure and loss of heat at the burner surface. The
gas flow requirements are roughly 1.0m3/h to 3.7m3/h
for natural gas or methane at a pressure to overcome line pressure losses.
- The specimen holder, pilot flame holder, fume stack, flame front viewing
rakes, radiation pyrometer and mirror are all assembled on the specimen support
frame. The arrangement of parts on this frame is shown in figures 1 and 2.
- A dummy specimen approximately 20mm thick, made of non-combustible
refractory board of 800± 100 kg/m3 density should be continuously
mounted on the apparatus in the position of the specimen during operation of the
equipment. This dummy specimen should only be removed when a test specimen is to
be inserted.
* Flashback limits the maximum operating level with
propane.
2 Instrumentation
2.1 Total radiation pyrometer
This should have a sensitivity substantially constant between the
thermal wave lengths of 1μ m and 9μ m and should view a
centrally-located area on the panel of about 150mm x 300mm. The instrument should be
mounted on the specimen support frame in such a manner that it can view the panel
surface.
2.2 Heat fluxmeters
It is desirable to have at least two fluxmeters for this test
method. They should be of the thermopile type with a nominal range of 0
kW/m2 to 50 kW/m2 and capable of safe operation at three
times this rating. One of these should be retained as a laboratory reference
standard. They should have been calibrated to an accuracy of within ±5%. The target
sensing the applied flux should occupy an area not more than 80 mm2 and
be located flush with and at the centre of the water-cooled 25mm circular exposed
metallic end of the fluxmeter. If fluxmeters of smaller diameter are to be used,
these should be inserted into a copper sleeve of 25mm outside diameter in such a way
that good thermal contact is maintained between the sleeve and water-cooled
fluxmeter body. The end of the sleeve and the exposed surface of the fluxmeter
should lie in the same plane. Radiation should not pass through any window before
reaching the target.
2.3 Timing devices
Both a chronograph and either an electric clock with a sweep
second hand or a digital clock should be provided to measure time of ignition and
flame advance. The chronograph for timing ignition and initial flame advance may
comprise a strip chart recorder with paper speed of at least 5 mm/s and an event
marker pen. Both the chronograph paper drive and the electric clock should be
operated through a common switch to initiate simultaneous operation when the
specimen is exposed. This may be either hand operated or actuated automatically as a
result of complete specimen insertion.
2.4
Recording millivoltmeter
A two-channel strip chart recording millivoltmeter having at least
one megohm input resistance should be used to record signals from the fume stack
thermocouples and the output from the radiation pyrometer. The signal from the fume
stack will in most instances be less than 15 mV but in some cases this may be
exceeded by a small amount. The sensitivity of the other channel should be selected
to require less than full scale deflection with the total radiation pyrometer of
fluxmeter chosen. The effective operating temperature of the radiant panel should
not normally exceed 93 5°C.
2.5
Digital voltmeter
A small digital millivoltmeter will be found convenient for
monitoring changes in operating conditions of the radiant panel. It should be
capable of indicating signal changes of 10μ or less.
3 Space for conducting tests
3.1 Special room
A special room should be provided for performance of this test.
The dimensions of it are not critical but it may be roughly 45m3 volume
with a ceiling height of not less than 2.5 m.
3.2 Fume exhaust system
An exhaust system should be installed above the ceiling with a
capacity for moving air and combustion products at a rate of 30m3/min.
The ceiling grill opening to this exhaust system should be surrounded by a 1.3 m x
1.3 m refractory fibre fabric skirt hanging from the ceiling down to 1.7 ± 0.1 m
from the floor of the room. The specimen support frame and radiant panel should be
located beneath this hood in such a way that all combustion fumes are withdrawn from
the room.
3.3 The apparatus
This should be located with a clearance of at least one metre
separation between it and the walls of the test room. No combustible finish material
of ceiling, floor or walls should be located within 2 m of the radiant heat source.
3.4 Air supply
Access to an exterior supply of air, to replace that removed by
the exhaust system, is required. This should be arranged in such a way that the
ambient temperature remains reasonably stable (for example: the air might be taken
from an adjoining heated building).
3.5 Room
draughts
Measurements should be made of air speeds near a dummy specimen
while the fume exhaust system is operating but the radiant panel and its air supply
are turned off. At a distance of 100mm the air flow perpendicular to the lower edge
at midlength of the specimen should not exceed 0.2 m/s in any direction.
4 Assembly and adjustment
4.1 General
The test conditions are essentially defined in terms of the
measured heat flux incident on a dummy specimen during calibration. Radiation
transfer will predominate, but convection transfer will also play a part. The flux
level incident at the specimen surface is a result of the geometrical
configuration between the radiant panel and the specimen, as well as the thermal
output from the radiant panel.
4.1.1
Both in original adjustment of test operating conditions and periodic verification
of this adjustment, the measured heat flux at the surface of the specimen is the
controlling criterion. This heat flux is measured by a fluxmeter (see 2.2) mounted
in a special dummy specimen(figure 14).
4.1.2 Between consecutive tests, the operating level should be
monitored either by use of a fluxmeter mounted in a dummy specimen as defined in
paragraph 3.3 of the Recommendation under "Definitions" or preferably by use of a
radiation pyrometer which has been previously periodically calibrated on the basis
of the readings of such a fluxmeter. This radiation pyrometer should be rigidly
fixed to the specimen-holder frame in such a manner that it continuously views the
radiating panel surface (see 2.1).
4.2 Mechanical alignment
Most of the adjustments of the components of the test
apparatus may be conducted in the cold condition. The position of the refractory
surface of the radiant panel with respect to the specimen must correspond with the
dimensions shown in figure 6. These relationships can be achieved by appropriate
use of shims between the panel and its mounting bracket, adjustment or separation
between the two main frames, and adjustment of the position of the specimen holder
guides. Detailed procedures for making these adjustments are suggested in
paragraph 5.
4.2.1 The fume stack for
heat release measurements should be mechanically mounted on the specimen support
frame in the position shown in figure 7. The method of mounting should ensure the
relative positions shown but should allow easy stack removal for cleaning and/or
repair. The compensating thermocouple should be mounted in such a manner that good
thermal contact is achieved while ensuring greater than one megohm electrical
resistance from the stack metal wall.
4.3 Thermal adjustment of panel operating level
Thermal adjustment of the panel operating level is achieved
by first setting an air flow of about 30m3/h through the panel. Gas is
then supplied and the panel ignited and allowed to come to thermal equilibrium
with a dummy specimen mounted before it. At proper operating condition, there
should be no visible flaming from the panel surface except when viewed from one
side parallel to the surface plane. From this direction, a thin blue flame very
close to the panel surface will be observed. An oblique view of the panel after a
15 min warm-up period should show a bright orange radiating surface.
4.3.1 With a water-cooled* fluxmeter
mounted in a special dummy specimen, the flux incident on the specimen should
correspond to the values shown in table 1. Compliance with this requirement is
achieved by adjustment of the gas flow. If necessary, small changes in air flow
can be made to achieve the condition of no significant flaming from the panel
surface. Precise duplication of the flux measurements specified in table 1 for the
50mm and 350mm positions on the basis of the fluxmeter calibration used will fix
the flux at the other stations well within the limits called for. This does not
mean that all other flux levels are correct, but it does ensure that a fixed
configuration or view geometry between the panel and specimen has been achieved.
To meet these requirements, it may be necessary to make small changes in the
specimen longitudinal position shown in figure 6. A plot and smooth curve should
be developed on the basis of the eight flux measurements required. The shape of
the curve should be similar to that defined by the typical data shown in table 1.
These measurements are important, since the experimental results are reported on
the basis of these flux measurements. If a total radiation pyrometer is to be used
to monitor panel operation, records of its signal should be kept following
successful completion of this calibration procedure. If a change in panel-specimen
axial position is necessary to meet the requirements for flux at the 50mm and
350mm positions, this should be accomplished by adjusting the screws connecting
the two frames. In this way, the pilot position with respect to the specimen will
remain unchanged. The specimen stop screw adjustment may be changed to meet the
flux requirements in the standard and then the position of the pilot burner mount
may require adjustment to maintain the 10± 2mm pilot spacing.
4.3.2 Once these operating conditions have been
achieved, all future panel operation should take place with the established air
flow with gas supply as the variable to achieve the specimen flux level as
calibrated. This level should be monitored with use of either a radiation
pyrometer fixed to view an area of the source surface or a fluxmeter mounted in a
dummy specimen, as defined in paragraph 3.3 under "Definitions", at the 350mm
position. If the latter method is used, the assembly of dummy specimen and
fluxmeter should remain in place between tests.
* Water cooling of the fluxmeter is required to avoid
erroneous signals at low flux levels. The temperature of the cooling water
should be controlled in such a manner that the fluxmeter body temperature
remains within a few degrees of room temperature. If this is not done,
correction of the flux measurement should be made for temperature difference
between the fluxmeter body and room temperature. Failure to supply water-cooling
may result in thermal damage to the thermal sensing surface and loss of
calibration of the fluxmeter. In some cases repairs and recalibration are
possible. 4.4 Adjustments and calibrations - general
The following adjustments and calibrations are to be
achieved by burning methane gas from the line heat source located parallel to, and
in the same plane as, the centreline of a dummy specimen located in position and
without fluxmeters. This line burner comprises a 2 m length of pipe of 9.1 mm
internal diameter. One end is closed off with a cap and a line of 15 holes of 3mm
diameter are drilled at 16mm spacing through the pipe wall. The gas burned as it
flows through this line of vertically positioned holes flames up through the
stack. The measured flow rate and the net or lower heat of combustion of the gas
serve to produce a known heat release rate which can be observed as a compensated
stack millivolt signal change. Prior to performing calibration tests, measurements
must be conducted to verify that the stack thermocouple compensation has been
properly adjusted.
4.5 Compensation adjustment
The fraction of the signal from the compensator thermocouple
which is subtracted from the stack thermocouple output should be adjusted by means
of the resistance of one leg of the potential divider shown in figure 10. The
purpose of this adjustment is as far as practical, to eliminate from the stack
signal the long-term signal changes resulting from the relatively slow stack metal
temperature variations. Figure 11 shows the curves resulting from
under-compensation, correct compensation, and over-compensation. These curves were
obtained by abruptly placing the lighted gas calibration burner adjacent to the
hot end of a dummy specimen and then extinguishing it. For this adjustment, the
calibration gas feed rate should be set to correspond to a heat rate of one kW.
The compensator potential divider should be adjusted to yield curves that show a
rapid rise to a steady state signal which is essentially constant over a 5 min
period following the first minute of transient signal rise. When the calibration
burner is shut off, the signal should rapidly decrease and reach a steady state
value within two minutes. Following this, there should be no long-term rise or
fall of the signal. Experience has shown that between 40% and 50% of the
compensation thermocouple signal should be included in the output signal to
achieve this condition. When properly adjusted, a square thermal pulse of 7 kW
should show not more than approximately 7% overshoot shortly after application of
the calibration flame ( see figure 11 ).
4.6 Fume stack calibration
With the adjustment described in 4.5 completed and a steady
state base signal having been achieved, stack calibration should be carried out
with the radiant panel operating at 50.5 kW/m2 and the pilot burner not
lit. The calibration of the stack millivolt signal rise should be made by
introducing and removing the line burner, as described in 4.4. The flow rate of
methane gas of at least 95% purity should be varied over the range of about
0.004m3/min to 0.02m3/min in sufficient increments to
permit plotting the data in a well defined curve of stack compensated millivolt
signal rise against the net or lower heat input rate. A similar calibration should
be performed with the calibration burner located at the cool end of the specimen.
The two curves should show agreement in indicated heat release rate within about
15%. A typical curve is shown in figure 12. The curve for the calibration burner
at the hot end of the specimen should be the one used for reporting all heat
release measurements. This completes the calibration and the test equipment is
ready for use.
5 Assembly and mechanical adjustment of the flammability test apparatus
The following instructions assume that parts of the flammability test apparatus
have been made according to the drawings. The radiant panel subassembly has been
completed with the exception of the support brackets and reverberatory screen. The
equipment can be assembled to permit test of specimens of thickness up to 50mm or
75mm. Unless there is a real need for test of thicker specimens, assembly for 50mm
specimens is preferable.
5.1 The panel
frame should be placed upright on a level floor, preferably in the location in which
the equipment will be used.
5.2 The
rotating ring should be mounted on its three guide bearings.
5.3 The panel mount frame should be bolted together, and to
the ring, by four bolts.
5.4 A check
should be made that the ring lies in a vertical plane. If the error is large, an
adjustment of the upper ring support-bearing location may be necessary. Prior to
making such an adjustment, it should be determined whether the error is due to
excessive clearance between the ring and bearing rollers. If this is the case,
rollers of larger diameter may correct the problem.
5.5 The four panel support brackets should be fastened to the
radiant panel at four corners. Do not use too much force in bolting these brackets
in place. Prior to mounting these brackets, one 35mm M9 cap screw is placed in the
hold that will be farthest from the panel end. These screws provide a means for
mounting the panel.
5.6 Four washers
should be placed on each of the panel mounting screws and the panel assembled on the
mount bracket.
5.7 The angularity of the
radiant panel surface with the plane of the mounting ring should be checked. This
can be accomplished by means of a carpenter's square and measurements to the
refractory tile surface at both ends of the panel. Any deviation from the required
15° angle may be adjusted by increasing or reducing the number of washers on the
mounting screws.
5.8 The radiant panel
should be rotated to face a specimen mounted in a vertical plane.
5.9 The panel surface should be checked with a level to
ensure that it also lies in a vertical plane.
5.10 The specimen frame with specimen support rails on side and bottom
positions and pilot burner holders assembled in approximate positions should be
brought up to the burner frame and the two frames fastened together with two bolts
and six nuts or two threaded rods and eight nuts. The spacing between the frames is
roughly 100mm.
5.11 The spacing of the
two sides of the frames is adjusted to ensure that the specimen support frame
longitudinal members are at a 15° angle to the radiant panel surface.
5.12 The single specimen holder side guide
rail for vertical specimen orientation should be adjusted so that it is at the
required 15° angle to the radiant panel surface.
5.13 An empty specimen holder should be slid into position on the rail
and the position of the upper guide fork adjusted to ensure that when a specimen is
inserted in the holder its surface will lie in a vertical plane.
5.14 The stop screw determining the axial position of
the specimen holder should be adjusted to ensure that the axis of the pilot burner
is 10±2mm from the closest exposed edge of the specimen. This adjustment should
again be made by use of an empty specimen holder and substitution of a 6 mm steel
rod of 250mm length for the pilot burner ceramic tube. When viewed from the back of
the specimen holder, the spacing between rod axis and the edge of the specimen
retaining flange of the holder should be 10±2mm.
5.15 With the specimen holder still in place against the top screw, the
spacing between the panel and specimen support frames should be adjusted to make
dimension B, figure 6, equal to about 125 mm. This adjustment is made by means of
the two screws fastening the frames together. In making this adjustment, it is
important to make equal adjustments on each side to maintain the angular
relationship called for in adjustments 5.11 and 5.12.
5.16 The nuts supporting the specimen holder side guide rail
should be adjusted to ensure that dimension A, figure 6, is 125±2mm. Again, equal
adjustments to the two mounting points are required. When doing this, a check should
be made to ensure that the guide rail and edge of the specimen holder are in a
horizontal plane. In making this adjustment, it is important to ensure that the 45mm
stack position dimension shown in figure 7 is maintained. Another way of adjustment
to dimension A is through changes in the number of washers mentioned in 5.6.
5.17 If necessary, procedure 5.13 should be
repeated.
5.18 The reverberatory screen
should be mounted on the radiant panel. This must be done in such a manner that it
is free to expand as it heats up during operation.
5.19 The viewing rake with 50mm pins is mounted on an angle
fastened to the specimen holder guide rail. Its position is adjusted so that pins
are located at multiples of 50mm distance from the closest end of the specimen
exposed to the panel. It should be clamped in this position.
6 Table 1 Calibration of flux to the specimen
Typical flux incident on the specimen and specimen positions
at which the calibration measurements are to be made. The flux at the 50mm and 350mm
positions should be matched. Calibration data at other positions should agree with
typical values within 10%.
| Distance from exposed end of
the specimen | Typical flux levels at the specimen | Calibration position to be used |
| 0 | 49.5 kW/m2 | |
| 50 | 50.5 | 50.5 kW/m2 |
| 100 | 49.5 | |
| 150 | 47.1 | × |
| 200 | 43.1 | |
| 250 | 37.8 | × |
| 300 | 30.9 | |
| 350 | 23.9 | 23.9 |
| 400 | 18.2 | |
| 450 | 13.2 | × |
| 500 | 9.2 | |
| 550 | 6.2 | × |
| 600 | 4.3 | |
| 650 | 3.1 | × |
| 700 | 2.2 | |
| 750 | 1.5 | × |
7 Figures
Figure 01 General view of the apparatus
Figure 02 View from specimen end
Figure 03 View from radiant panel end
Figure 04 Radiant panel with reverberatory wires viewed through specimen mount frame
Figure 05 Pilot burner and mount
Figure 06 Specimen - panel arrangement
Figure 07 Stack - specimen position dimensions
Figure 08 Pilot burner details and connections
Figure 09 Position of pilot flame
Figure 10 Diagrammatic sketch of thermocouple circuit
Two sets of thermocouples and lead wires are required. The
wire size and lengths within the fume T.C. group must be the same to ensure proper
signal aberaging. The parallel connection of the couples may be achieved at the
mixing box by plug connection of the leads. This allows quick remaval and checks
for continuity and grounding problemes with minimum delay. No cold junction should
be used but the signal mixing box shall be shielded from panel radiation.
Figure 11 Response behaviour of heat release signal to a square wave thermal pulse
Figure 12 Typical stack calibration
Figure 13 Conversion of the millivolt signal rise U to heat release of the specimen
a - millivolt signal change recorded during test
b - millivolt signal to heat release rate curve
Figure 14 Special calibration dummy specimen for flux gradien calibration