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Flammability

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Endpoint:
flammable gases
Type of information:
experimental study
Adequacy of study:
key study
Study period:
01/08/2019 - 29/03/2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
other: ASTM E681-2009
Version / remarks:
None
Deviations:
no
Principles of method if other than guideline:
Test method is based upon observation of flame propagation after electrical ignition, and is a standard method.
GLP compliance:
not specified
Specific details on test material used for the study:
Test substance was of 99.5% purity.
Key result
Parameter:
lower explosion limit
Value:
>= 12 vol%
Remarks on result:
other: Not flammable
Key result
Parameter:
upper explosion limit
Value:
>= 12 vol%
Remarks on result:
other: Not flammable
Interpretation of results:
GHS criteria not met
Conclusions:
Testing on HCFO-1224yd(Z) flammability has shown, by strict adherence to ASHRAE 34, that HCFO-1224yd(Z) is non-flammable at 60°C.
Endpoint:
flammable gases
Type of information:
experimental study
Adequacy of study:
key study
Study period:
24/07/2017 - 17/08/2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method A.11 (Flammability (Gases))
Deviations:
no
GLP compliance:
yes (incl. certificate)
Key result
Parameter:
lower explosion limit
Value:
>= 16 vol%
Key result
Parameter:
upper explosion limit
Value:
<= 19 vol%
Conclusions:
The test material is considered flammable.
Executive summary:

The test material is considered flammable with flammable range between 16 -19% volume

Description of key information

Key value for chemical safety assessment

Flammability:
not classified

Additional information

Justification for classification or non-classification

Introduction

 

The flammability of HCFO-1224yd(Z) has been assessed using three different testing procedures: ASTM E681-2009,BS EN 1876:2009 andEU Reg (EC) 440/2008, Annex Part A Test Method A.11. The substance performed differently in each study and, as such, a weight of evidence approach has been used to assess the data, as advised in paragraph R 7.1.10.1 of ECHA Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7a: Endpoint specific guidance Version 6.0 – July 2017 (see below).

 

Weight of evidence

Where no single source of existing data (study reports, QSAR, literature data) is considered sufficiently reliable, thus not fully meeting the criteria in section 1.1.1 of Annex XI to REACH, or where several sources of similar reliability with deviating results exist, a weight of evidence approach may be used. The criteria in section 1.2 of Annex XI to REACH must then be met.

 

Test Results

 

1.     ASTM E681-2009

 

HCFO-1224yd(Z) was tested for flammability according to ASTM E681-2009 and using the procedure required in ASHRAE Standard 34-2013. The test was conducted at 60oC, using air which had a humidity of 0.0088g water vapour/gm dry air, which equates to a relative humidity of 50% at 23oC and 101.3kPa. Flame propagation was determined as described in Appendix B1 of the ASHRAE Standard, which is the 90-degree fan criterion. HCFO-1224yd(Z) was tested at concentrations of 1.0% to 12.0% vol in air at increments of 1.0% and also at 9.5% (a total of 13 test runs). No flame propagation was observed at any concentration tested.

 

It was concluded that HCFO-1224yd(Z) was non-flammable at 60oC according to the criteria of ASHRAE Standard 34 and it was decided that it was not necessary to test the substance at 23oC.

 

2.     BS EN 1876:2009

 

HCFO-1224yd(Z) was tested for flammability according toBS EN 1876:2009 (Method T).The method allows the determination of whether gases mixed with air at room temperature (circa 20°C) and atmospheric pressure are flammable. During the test, a spark is passed through the gas mixture and it is observed whether or not a flame occurs and detaches itself from the ignition source and propagates independently. If a flame detachment and an upwards propagation of at least 100 mm is observed, the test substance is classified as “Flammable”.

 

HCFO-1224yd(Z) was tested at concentrations of 1.0% to 19.0% vol in air at increments of 1.0% (a total of 19 test runs). A glow around the spark was observed at concentrations of HCFO-1224yd(Z) of 5.0 to 12.0%. A flame was observed when tested at concentrations of 13.0, 14.0 and 15.0%, but no detachment of the flame was observed. No flame was observed when tested at concentrations of 16.0% and above.

 

It was concluded that HCFO-1224yd(Z) was non-flammable according to the criteria ofBS EN 1876:2009.

 

3.     EU Reg (EC) 440/2008, Annex Part A Test Method A.11

 

HCFO-1224yd(Z) was tested for flammability in accordance withEU Reg (EC) 440/2008, Annex Part A Test Method A.11 (A.11 Test Protocol). The method allows the determination of whether gases mixed with air at room temperature (circa 20°C) and atmospheric pressure are flammable.The relevant data for the determination of whether the test substance is a non-flammable gas or a flammable gas is the occurrence of an independently propagated flame whena spark is passed through the gas mixture.

 

HCFO-1224yd(Z) was tested at concentrations of 1.0% to 10.0% vol in air at increments of 1.0%, at 12.0%, at concentrations of 14.0% to 20.0% at increments of 1.0%, at 22.0% and at 26.0% (a total of 27 test runs). A glow around the spark was observed at concentrations of HCFO-1224yd(Z) of 5.0 to 12.0%. An orange flame that did not propagate was observed when tested at concentrations of 15.0% and 20.0%. An orange flame that propagated no more than 70mm was observed when tested at concentrations of 16.0, 17.0, 18.0 and 19.0%. No flame was observed when tested at concentrations of 22.0% and above.

 

The criteria for the determination of the flammability of a gas at 20°C according to this method are as follows:

 

Category 1 Extremely Flammable Gas;

 

(a) ignitable when in a mixture of 13 % or less by volume in air; or

(b) have a flammable range with air of at least 12 percentage points regardless of the lower

flammable limit.

 

Category 2 Flammable Gas.

 

Gases, other than those of Category 1, which, at 20°C and a standard pressure of 101.3 kPa, have a flammable range while mixed in air.

 

Consequently, whilst it had a flammable range but did not ignite at concentrations of 13.0% or less, it was concluded that HCFO-1224yd(Z) would be classified as a Category 2 Flammable Gas according to the criteria ofEU Reg (EC) 440/2008, Annex Part A Test Method A.11.

 

It should be noted that this test, as conducted, also complied with test method BS EN 1876:2009. As the flame was not propagated further than 100 mm at any of the concentrations tested, the results of this study would indicate thatHCFO-1224yd(Z) would be classified as a non-flammable according to the criteria ofBS EN 1876:2009.

 

Discussion.

 

Three flammability studies have been performed with HCFO-1224yd(Z) according to different test protocols, two of which found the test substance to be non-flammable and a third which showed it to be flammable.

 

The studies conducted according to bothBS EN 1876:2009 andEU Reg (EC) 440/2008, Annex Part A Test Method A.11were conducted at the same facility (DEKRA Chilworth Laboratory) using the same test apparatus, yet they provided different results. Both tests were conducted to GLP and were conducted on 28/29.03.19 andbetween 24.07.17 and 17.08.17respectively. Possible reasons for these differences have been considered and discussed with the facility, where appropriate.

 

1.     Test Substance.

 

The samples of test substance for both studies were supplied by the manufacturer, Asahi Glass Co. Ltd., from their Chiba plant in Japan.

 

The Certificate of Analysis (CoA) for the sample submitted for the study conducted to the A.11 test protocol showed that the sample was 99.444%(Z)-1-Chloro-2,3,3,3-tetrafluoropropene, with its optical isomer, (E)-1-Chloro-2,3,3,3-tetrafluoropropene, being declared as an impurity and being present at 0.341%.

 

The Certificate of Analysis (CoA) for the sample submitted for the study conducted to BS EN 1876:2009 showed that the sample was 99.48%(Z)-1-Chloro-2,3,3,3-tetrafluoropropene, with its optical isomer, (E)-1-Chloro-2,3,3,3-tetrafluoropropene, being declared as an impurity and being present at 0.47%.

 

The report of the test conducted to ASTM E681-2009 does not include a CoA. However, the following statement is included in the report – “There are no contaminants or impurities, including isomeric and decomposition impurities, from manufacturing, transport or storage that are known to increase flammability or toxicity of the blend within the accuracy of the RCL.” (The definition of RCL is unknown.)

 

Taking all of this information into account, it is unlikely that the small differences in the levels of impurity in the two samples tested by DEKRA would explain the difference in performance of the samples in the two studies.

 

2.     Experimental Equipment.

 

The study protocols provided by the laboratory for both studies described a number of variables that may have an impact on the level of energy input to the system; e.g. distance between the two electrodes (the protocol states that this can vary between 3 and 5 mm; output voltage (the protocol states that this can vary between 10 and 15 kV); duration of spark (the protocol states that the spark is offered for 0.5 seconds).

DEKRA have stated that there were no changes or modifications to the experimental apparatus that was used to perform the two studies and that variability in the spark time would not have occurred, as itis controlled by a relay and therefore should be unchanged.

 

It is concluded that changes to the experimental equipment would not have contributed to the difference in performance of HCFO-1224yd(Z) in the two studies.

 

There are significant differences in the design of the test apparatus used in both the BS EN 1876:2009 andthe A.11 Test Protocol and that used inASTM E681-2009 and the protocols that are used. The two former test systems employ a cylindrical vessel, into which the test gas is introduced at the bottom. The ASTM method employs a spherical flask which eliminates “wall effect” issues and increase the likelihood of full homogenisation of the test gas in the vessel. Furthermore, the humidity in the ASTM test system is controlled, the criteria for ignition is more robust and the temperature of the test atmosphere can be monitored. These differences lead to a greater degree of confidence in the results of the ASTM test protocol.

 

3.     Ambient Conditions.

 

It is possible that differences in the ambient conditions (barometric pressure, humidity and temperature) may have contributed to the difference in performance of HCFO-1224yd(Z) in the two studies.

 

 

2017

2019

DATES

24thJuly to 9thAugust

28thand 29thMarch

Barometric Pressure

Ranged between 100.8 kPa and 101.7 kPa

103.6 kPa and 103.1 kPa

Humidity

Ranged between 46% and 58%

24% and 26%

Temperature

19 – 21°C

19 – 21°C

 

 

There was only a minimal difference in the barometric pressure at the times that the two studies were conducted. It is unlikely that this small difference would have contributed to the difference in performance of HCFO-1224yd(Z) in the studies.

 

There was a significant difference in the humidity at the times that the two studies were conducted. It would be reasonable to assume that substances would be more prone to ignite under conditions of lower humidity. As such, one might expect that the conditions of the test conducted in 2019 would have been more favourable to support an ignition. In fact, the opposite occurred; ignition of HCFO-1224yd(Z) was observed at a time when the humidity was high. Furthermore, moisture-free compressed gas is used to prepare the gas mixture that is introduced to the test apparatus. Consequently, the ambient humidity would have no impact on the performance of the tests. It is concluded that differences in humidity did not contribute to the difference in performance of HCFO-1224yd(Z) in the studies.

 

Conclusion

There are no clear factors in the conduct of the three studies that can explain the difference of performance of HCFO-1224yd(Z). It is generally known that halogenated compounds are difficult to ignite. In the experience of DEKRA, it is not uncommon for non-flammable compounds to show a flame upon initiation of the spark. Sometimes the flame propagates and sometimes it does not. This experimental variation appears to be the most likely explanation of the results of the studies conducted by DEKRA. Furthermore, critical differences in the conduct of the ASTM test lead to a greater degree of confidence in the results of the ASTM test protocol.

 

Taking all of these points into account, it is concluded that the weight of evidence supports the conclusion that HCFO-1224yd(Z) is Not Flammable.