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Protective clothing against the effects of heat
Journal of Occupational
Accidents,
11 (1990)
221
221-228
Elsevier
Protective Clothing against the Effects of Heat KURT
JUNG
Occupational (Received
Safety Institute
- BZA, D-5205 Sankt Augustin
(W. Germany)
22 March 1989; accepted 24 October 1989)
ABSTRACT Jung, K., 1990. Protective 11: 221-228. Protective
clothing against the effects of heat. Journal of Occupational
Accidents,
clothing against the effects of heat and welding has to meet the requirements
of the
corresponding use. In addition to basic requirements for protective clothing the following items were investigated: the reaction to liquid pig iron and welding droplets as well as inflammability. Based on the corresponding German and International amined in the laboratory and in the field. The results of these tests were translated account industrial experience.
standards these characteristics
into safety technological
requirements
were ex-
taking into
INTRODUCTION
Within the framework of research contracts of professional associations for the iron and metal industry, the Occupational Safety Institute - BIA - performed tests to establish the safety level of protective clothing used in workplaces exposed to heat. Technical safety requirements had to be developed for a DIN standard. This required examination of the influences and factors responsible for reduced protection. One objective of this study was to compare the protection and durability of heat-proof clothing, that was free of asbestos with asbestos containing clothing to promote asbestos substitution. The essential procedures and findings are presented in this paper. FLAME-RESISTANT
CLOTHING
For this type of clothing to be effective good behaviour against ignition is essential. This behaviour was tested according to DIN 54336 (Deutsches Institut fiir Normung, 1980a) ignition. The outcome of these tests determined the classification (Table 1) according to DIN 66083 (Deutsches Institut fur Normung, 198Ob). Flame-resistant clothing should correspond at least to classification S-b.
0376-6349/90/$03.50
0 1990 Elsevier Science Publishers B.V.
TABLE
1
Classification Burning-class
Is -a S-b sL -< S-d
of burning behaviour DIN 66083 After-flame time (s)
<2 < 3 < 20
After-glow
Melting
Dripping
time (s)
<5 <25
no no
no no no
Damaged length
Flame spread time
(mm)
(mm/s)
<:10 < 150 a
S-e
G.30 < 70
“The second marker thread 400 mm from the sample hemline must not be severed.
The performance levels against ignition determined for new clothes should be maintained over the entire duration of use. Protective clothing is exposed to varying stress factors in different workplace atmospheres the destructive effect of which may be reinforced by the many cleaning procedures used in laundries. In cooperation with five metal plants, we investigated the influence of operational stress factors during the wearing of protective clothing including cleaning in specialised laundries. Each plant supplied new protective suits as well as used and cleaned clothing for the tests. For testing purposes, BIA received. _ new clothing; _ clothing subjected to 10 wearing/cleaning cycles; _ clothing subjected to 20 wearing/cleaning cycles; and _ clothing subjected to 30 wearing/cleaning cycles. The behaviour of this clothing against ignition was determined. These results were compared with the test results obtained from 6 new suits after cleaning 25 times in the laboratory at 93 ‘C. To sum up it can be said that the flame-resistant protective suits used in metal plants have to be assessed differentially (Fig. 1) . Even material treated with PROBAN, which is supposed to protect permanently against flames, only partly meet the requirements of classification S-b after 20 wearing/cleaning cycles. It is remarkable that some manufacturers guarantee the fulfilment of the requirements regarding burning behaviour for up to 40 or 50 machine boiling procedures. Results on the burning behaviour indicate distinctly the variable quality of flame-resistant materials. This has to be considered when providing protective clothing for different purposes. Moreover, proper cleaning procedures have to be taken care of. Materials not permanently equipped against flames by FLAMMENTIN can
223
ma(g/m-Z) Cotton - PRO6AN:400
:461
:446
NEW Fig. 1. Burning behaviour,
10
20 25 (DIN) Number of cleanings
30
influence of cleaning.
be classified as S-b only when new. After only 10 wearing/cleaning cycles the material could only be classified S-d although it had been subjected to a repeat treatment after each cycle. After 30 wearing/cleaning cycles it only corresponded to category S-e, thus revealing the problems of a proper repeat treatment. We also have to consider the fact that, in practice, suits are subjected to at least 40 wearing/cleaning cycles before disposal. In addition, results obtained for the burning behaviour of materials cleaned in laundries and laboratories were found to be comparable. HEAT PROTECTIVE
CLOTHING
The aim was to recommended substitutes for asbestos in heat protective clothing while retaining the protective effect and durability. The behaviour of this clothing against molten masses is the relevant protective function. Based on thorough literature search, asbestos substitutes suitable for heat protective clothing were tabulated. The table contains 179 potential asbestos substitutes. In cooperation with five metal plants and three manufacturers of heat protective clothing, 88 materials were selected for tests against liquid pig iron (Fig. 2). Asbestos cloth was also tested for comparison. The average quantity of molten iron was 1150 g, the pig iron temperature was 1460’ C. In principle the test was done as described in ISO-DIS 9185 (International Organization for Standardization, 1988a). Subsequently, 11 persons inspected and assessed the 89 exposed materials (Table 2 ) . The materials thought to be appropriate (group 1 and 2 ) were ranked
224
Fig. 2. Reaction TABLE Reaction
to molten masses, poring tests.
2 to molten masses, subjective
Group
Assessment
1 2 3
As asbestos substitute l suitable . with restrictions . unsuitable
evaluation
Note: Materials have to be evaluated: (a) according to their visual appearance considering front and back; and (b) neglecting available personal experiences and other possibly known mechanical/technological characteristics.
from best to worst. Materials unanimously evaluated as unsuitable (group 3 ) were discarded and were not included in further assessments. Thirty-one materials remained, 30 of them did not contain asbestos. A statistical analysis of the subjective evaluation of these 30 materials showed that 10 were better, 1 the same and 19 worse than asbestos. This outcome was confirmed by a repeat trial. Based on the results of burning behaviour, the reaction to heat radiation and liquid pig iron as well as mechanical/technological characteristics like mass
225
Glassf ibre Glf. PBI&vlar/Glf. PBIIKevlar/Glf. INIx
Aramid
Kevlar/Glf. Kev1arICarbon Leather/sheet PBIIKevlar/Glf. KevlarAJiscose Kevlar/Carbon Asbestos I I I I I I I I I I I I
KevlarICarbon KevlarIGlf, Kev1arICarbon Glass f ibre Sebatan-Leather KevlarIGlf Preox id ized PAN PBI/Glf.
I I I I I I
I
1 I I I I
q metal 1ised
Ceramic
surf ace
PBI/Kevlar/Glf. PBIIKevlar/Glf,
rretallised surf ace
Kevlar/Carbon Preatex
n Asbestos
Glass f ibre Ceramic Preatex 38 m
40
1988
Fig. 3. Heat protective
50 Total
clothing, appropriate
68 points
asbestos substitutes.
scored
70
a0
226
per unit area, breaking force and tear propagation behaviour, the various materials were assessed. According to the results obtained, points were allocated to individual parameters. More points were given for a parameter the better the material behaved for that parameter. The scores obtained were between 35 and 71 points. Asbestos, for instance, achieved a total of 59 points. To sum up the results of this study it can be said that asbestos in heat protective clothing can be replaced by other materials. Recommended materials are summarized in Fig. 3 on the basis of the total score. PROTECTIVE
CLOTHING
FOR WELDERS
The reaction of this clothing to welding droplets is the relevant protective function. In principle the test was done as described in IS0 9150 (International Organization for Standardization, 198813). The tip of a metal wire is melted by an oxygen-acetylene flame. The generated drops are directed against a vertically positioned sample via an inclined guide. The rise in temperature on the back of the sample is measured by a probe. The number of drops necessary to obtain a temperature increase of 40
b
\ Burner
jet Drop
guide
Temperature Increase A T[Kl (b)
(a)
ma = 406
0
1 -
Fig. 4. Reaction
2 Time
1 [mln]
to welding droplets, test scheme.
3
g/m*
227
1
Number of drops
150
300
450
600
4 750
Mass per unit area of material .s ma (g/m*21 BIA 1988 Fig. 5. Reaction to welding droplets, trend analysis.
K on the back of the sample serves as the assessment parameter. The experimental setup is shown in Fig. 4. This figure also shows two typical curves of the temperature-time on the back of the sample. While for sample “a” a temperature rise of 40 K, i.e. an increase from 25 to 65”C, was observed after applying 14 drops, sample “b” required more than 60 drops. Altogether we tested the reaction to welding droplets for 38 different materials. Figure 5 shows the results, indicating that higher mass per unit area requires a greater number of drops to obtain a temperature rise of 40 K. The regression line in the figure can only serve as a guide since in addition to mass per unit area the kind of material and the fabric density influence its protective capacity. CONCLUSIONS
The reaction of heat and welders protective clothing to flame, liquid pig iron and welding droplets are most essential for assessing the relevant protective function. The tested materials are to be assessed differentially. The test results show differences between the permanently flame-resistant and the not permanently equipped materials with regard to the inflammability of the materials. Some of the permanently flame-resistant equipped materials do not meet the requirements guaranteed by the manufacter already after 20 wearing/cleaning cycles.
228
Based on a literature search 179 potential asbestos substitutes were listed. Liquid pig iron was poured on 88 of these. The assessment proved 30 materials to be suitable as asbestos substitutes. The tests with welding droplets showed a favourable influence of the mass per unit area. The higher mass per unit area, the smaller the heat transfer created by the welding droplets impinged on the material. Nevertheless, type and fabric density of the material are of importance, too. Detailed information on methodology, materials and results of these investigations are given in the following BIA Reports (in German): - The influence of different factors on durability and inflammability of fabrics for heat protective clothing (Schltiter et al., 1988); - Asbestos substitutes for heat-proof clothing (Schliiter et al., 1987); and _ Investigations on the protective effect of protective clothing for welders (Schliiter et al., 1986).
REFERENCES Deutsches Institut Ztindung durch Deutsches Textile Berlin.
ftir Normung, 1980a. Bestimmung des Brennverhaltens Kantenbeflammung: DIN 54 336. Beuth Verlag GmbH,
Institut ftir Normung, 1980b. Kennwerte ftir das Brennverhalten Flachengebilde ftir Arbeitsund Schutzkleidung: DIN 66083.
International Organization for Standardization, tance of materials to molten metal splash: International Organization for Standardization,
Lotrechtmethode Berlin. textiler Erzeugnisse; Beuth Verlag GmbH,
1988a. Protective clothing - Assessment ofresisISO/DIS 9185. Beuth Verlag GmbH, Berlin. 198813. Protective clothing - Determination of
behaviour of materials on impact of small splashes of molten metal: IS0 9150. Beuth Verlag GmbH, Berlin. Schltiter, R., Jung, K., Cieslik, J., Fendel, R., Unger, H. and Wilm, N., 1986. Untersuchungen zur Schutzwirkung von Schweisserschutzanziigen: BIA-Report 4186. BIA, St. Augustin. Schliiter, R., Jung, K., Cieslik, J. and Unger, H., 1987. Asbestersatzstoffe fiir Hitzeschutzkleidung: BIA-Report 4187. BIA, St. Augustin. Schltiter, R., Jung, K., Cieslik, J., Fendel, R., Unger, H. and Wilm, N., 1988. Einfluss verschiedener Faktoren auf die Haltbarkeit und Entflammbarkeit von Geweben fiir Hitzeschutzkleidung: BIA-Report 5188. BIA, St. Augustin.
Accidents,
11 (1990)
221
221-228
Elsevier
Protective Clothing against the Effects of Heat KURT
JUNG
Occupational (Received
Safety Institute
- BZA, D-5205 Sankt Augustin
(W. Germany)
22 March 1989; accepted 24 October 1989)
ABSTRACT Jung, K., 1990. Protective 11: 221-228. Protective
clothing against the effects of heat. Journal of Occupational
Accidents,
clothing against the effects of heat and welding has to meet the requirements
of the
corresponding use. In addition to basic requirements for protective clothing the following items were investigated: the reaction to liquid pig iron and welding droplets as well as inflammability. Based on the corresponding German and International amined in the laboratory and in the field. The results of these tests were translated account industrial experience.
standards these characteristics
into safety technological
requirements
were ex-
taking into
INTRODUCTION
Within the framework of research contracts of professional associations for the iron and metal industry, the Occupational Safety Institute - BIA - performed tests to establish the safety level of protective clothing used in workplaces exposed to heat. Technical safety requirements had to be developed for a DIN standard. This required examination of the influences and factors responsible for reduced protection. One objective of this study was to compare the protection and durability of heat-proof clothing, that was free of asbestos with asbestos containing clothing to promote asbestos substitution. The essential procedures and findings are presented in this paper. FLAME-RESISTANT
CLOTHING
For this type of clothing to be effective good behaviour against ignition is essential. This behaviour was tested according to DIN 54336 (Deutsches Institut fiir Normung, 1980a) ignition. The outcome of these tests determined the classification (Table 1) according to DIN 66083 (Deutsches Institut fur Normung, 198Ob). Flame-resistant clothing should correspond at least to classification S-b.
0376-6349/90/$03.50
0 1990 Elsevier Science Publishers B.V.
TABLE
1
Classification Burning-class
Is -a S-b sL -< S-d
of burning behaviour DIN 66083 After-flame time (s)
<2 < 3 < 20
After-glow
Melting
Dripping
time (s)
<5 <25
no no
no no no
Damaged length
Flame spread time
(mm)
(mm/s)
<:10 < 150 a
S-e
G.30 < 70
“The second marker thread 400 mm from the sample hemline must not be severed.
The performance levels against ignition determined for new clothes should be maintained over the entire duration of use. Protective clothing is exposed to varying stress factors in different workplace atmospheres the destructive effect of which may be reinforced by the many cleaning procedures used in laundries. In cooperation with five metal plants, we investigated the influence of operational stress factors during the wearing of protective clothing including cleaning in specialised laundries. Each plant supplied new protective suits as well as used and cleaned clothing for the tests. For testing purposes, BIA received. _ new clothing; _ clothing subjected to 10 wearing/cleaning cycles; _ clothing subjected to 20 wearing/cleaning cycles; and _ clothing subjected to 30 wearing/cleaning cycles. The behaviour of this clothing against ignition was determined. These results were compared with the test results obtained from 6 new suits after cleaning 25 times in the laboratory at 93 ‘C. To sum up it can be said that the flame-resistant protective suits used in metal plants have to be assessed differentially (Fig. 1) . Even material treated with PROBAN, which is supposed to protect permanently against flames, only partly meet the requirements of classification S-b after 20 wearing/cleaning cycles. It is remarkable that some manufacturers guarantee the fulfilment of the requirements regarding burning behaviour for up to 40 or 50 machine boiling procedures. Results on the burning behaviour indicate distinctly the variable quality of flame-resistant materials. This has to be considered when providing protective clothing for different purposes. Moreover, proper cleaning procedures have to be taken care of. Materials not permanently equipped against flames by FLAMMENTIN can
223
ma(g/m-Z) Cotton - PRO6AN:400
:461
:446
NEW Fig. 1. Burning behaviour,
10
20 25 (DIN) Number of cleanings
30
influence of cleaning.
be classified as S-b only when new. After only 10 wearing/cleaning cycles the material could only be classified S-d although it had been subjected to a repeat treatment after each cycle. After 30 wearing/cleaning cycles it only corresponded to category S-e, thus revealing the problems of a proper repeat treatment. We also have to consider the fact that, in practice, suits are subjected to at least 40 wearing/cleaning cycles before disposal. In addition, results obtained for the burning behaviour of materials cleaned in laundries and laboratories were found to be comparable. HEAT PROTECTIVE
CLOTHING
The aim was to recommended substitutes for asbestos in heat protective clothing while retaining the protective effect and durability. The behaviour of this clothing against molten masses is the relevant protective function. Based on thorough literature search, asbestos substitutes suitable for heat protective clothing were tabulated. The table contains 179 potential asbestos substitutes. In cooperation with five metal plants and three manufacturers of heat protective clothing, 88 materials were selected for tests against liquid pig iron (Fig. 2). Asbestos cloth was also tested for comparison. The average quantity of molten iron was 1150 g, the pig iron temperature was 1460’ C. In principle the test was done as described in ISO-DIS 9185 (International Organization for Standardization, 1988a). Subsequently, 11 persons inspected and assessed the 89 exposed materials (Table 2 ) . The materials thought to be appropriate (group 1 and 2 ) were ranked
224
Fig. 2. Reaction TABLE Reaction
to molten masses, poring tests.
2 to molten masses, subjective
Group
Assessment
1 2 3
As asbestos substitute l suitable . with restrictions . unsuitable
evaluation
Note: Materials have to be evaluated: (a) according to their visual appearance considering front and back; and (b) neglecting available personal experiences and other possibly known mechanical/technological characteristics.
from best to worst. Materials unanimously evaluated as unsuitable (group 3 ) were discarded and were not included in further assessments. Thirty-one materials remained, 30 of them did not contain asbestos. A statistical analysis of the subjective evaluation of these 30 materials showed that 10 were better, 1 the same and 19 worse than asbestos. This outcome was confirmed by a repeat trial. Based on the results of burning behaviour, the reaction to heat radiation and liquid pig iron as well as mechanical/technological characteristics like mass
225
Glassf ibre Glf. PBI&vlar/Glf. PBIIKevlar/Glf. INIx
Aramid
Kevlar/Glf. Kev1arICarbon Leather/sheet PBIIKevlar/Glf. KevlarAJiscose Kevlar/Carbon Asbestos I I I I I I I I I I I I
KevlarICarbon KevlarIGlf, Kev1arICarbon Glass f ibre Sebatan-Leather KevlarIGlf Preox id ized PAN PBI/Glf.
I I I I I I
I
1 I I I I
q metal 1ised
Ceramic
surf ace
PBI/Kevlar/Glf. PBIIKevlar/Glf,
rretallised surf ace
Kevlar/Carbon Preatex
n Asbestos
Glass f ibre Ceramic Preatex 38 m
40
1988
Fig. 3. Heat protective
50 Total
clothing, appropriate
68 points
asbestos substitutes.
scored
70
a0
226
per unit area, breaking force and tear propagation behaviour, the various materials were assessed. According to the results obtained, points were allocated to individual parameters. More points were given for a parameter the better the material behaved for that parameter. The scores obtained were between 35 and 71 points. Asbestos, for instance, achieved a total of 59 points. To sum up the results of this study it can be said that asbestos in heat protective clothing can be replaced by other materials. Recommended materials are summarized in Fig. 3 on the basis of the total score. PROTECTIVE
CLOTHING
FOR WELDERS
The reaction of this clothing to welding droplets is the relevant protective function. In principle the test was done as described in IS0 9150 (International Organization for Standardization, 198813). The tip of a metal wire is melted by an oxygen-acetylene flame. The generated drops are directed against a vertically positioned sample via an inclined guide. The rise in temperature on the back of the sample is measured by a probe. The number of drops necessary to obtain a temperature increase of 40
b
\ Burner
jet Drop
guide
Temperature Increase A T[Kl (b)
(a)
ma = 406
0
1 -
Fig. 4. Reaction
2 Time
1 [mln]
to welding droplets, test scheme.
3
g/m*
227
1
Number of drops
150
300
450
600
4 750
Mass per unit area of material .s ma (g/m*21 BIA 1988 Fig. 5. Reaction to welding droplets, trend analysis.
K on the back of the sample serves as the assessment parameter. The experimental setup is shown in Fig. 4. This figure also shows two typical curves of the temperature-time on the back of the sample. While for sample “a” a temperature rise of 40 K, i.e. an increase from 25 to 65”C, was observed after applying 14 drops, sample “b” required more than 60 drops. Altogether we tested the reaction to welding droplets for 38 different materials. Figure 5 shows the results, indicating that higher mass per unit area requires a greater number of drops to obtain a temperature rise of 40 K. The regression line in the figure can only serve as a guide since in addition to mass per unit area the kind of material and the fabric density influence its protective capacity. CONCLUSIONS
The reaction of heat and welders protective clothing to flame, liquid pig iron and welding droplets are most essential for assessing the relevant protective function. The tested materials are to be assessed differentially. The test results show differences between the permanently flame-resistant and the not permanently equipped materials with regard to the inflammability of the materials. Some of the permanently flame-resistant equipped materials do not meet the requirements guaranteed by the manufacter already after 20 wearing/cleaning cycles.
228
Based on a literature search 179 potential asbestos substitutes were listed. Liquid pig iron was poured on 88 of these. The assessment proved 30 materials to be suitable as asbestos substitutes. The tests with welding droplets showed a favourable influence of the mass per unit area. The higher mass per unit area, the smaller the heat transfer created by the welding droplets impinged on the material. Nevertheless, type and fabric density of the material are of importance, too. Detailed information on methodology, materials and results of these investigations are given in the following BIA Reports (in German): - The influence of different factors on durability and inflammability of fabrics for heat protective clothing (Schltiter et al., 1988); - Asbestos substitutes for heat-proof clothing (Schliiter et al., 1987); and _ Investigations on the protective effect of protective clothing for welders (Schliiter et al., 1986).
REFERENCES Deutsches Institut Ztindung durch Deutsches Textile Berlin.
ftir Normung, 1980a. Bestimmung des Brennverhaltens Kantenbeflammung: DIN 54 336. Beuth Verlag GmbH,
Institut ftir Normung, 1980b. Kennwerte ftir das Brennverhalten Flachengebilde ftir Arbeitsund Schutzkleidung: DIN 66083.
International Organization for Standardization, tance of materials to molten metal splash: International Organization for Standardization,
Lotrechtmethode Berlin. textiler Erzeugnisse; Beuth Verlag GmbH,
1988a. Protective clothing - Assessment ofresisISO/DIS 9185. Beuth Verlag GmbH, Berlin. 198813. Protective clothing - Determination of
behaviour of materials on impact of small splashes of molten metal: IS0 9150. Beuth Verlag GmbH, Berlin. Schltiter, R., Jung, K., Cieslik, J., Fendel, R., Unger, H. and Wilm, N., 1986. Untersuchungen zur Schutzwirkung von Schweisserschutzanziigen: BIA-Report 4186. BIA, St. Augustin. Schliiter, R., Jung, K., Cieslik, J. and Unger, H., 1987. Asbestersatzstoffe fiir Hitzeschutzkleidung: BIA-Report 4187. BIA, St. Augustin. Schltiter, R., Jung, K., Cieslik, J., Fendel, R., Unger, H. and Wilm, N., 1988. Einfluss verschiedener Faktoren auf die Haltbarkeit und Entflammbarkeit von Geweben fiir Hitzeschutzkleidung: BIA-Report 5188. BIA, St. Augustin.