A review by Amir Samadijavan
Introduction
A recently initiated ballot for registration of work item for the revision of ISO 21898-2004 proposed a significant change of this norm aiming to revise the UV test procedure in the annex A of this norm. The current version of the standard doesn’t consider outdoor storage of FIBC unless they have been specially designed for outdoor storage. Conditions for outdoor storage have to be specified and agreed between suppliers and users. Knowing that FIBC ́s very often being stored outdoor, leaves the current version of the standard room for interpretation and leads to dispute between stakeholders. It is therefore a grey area where users don’t often know under which conditions and for how long they can store filled FIBC outdoor.
This is indeed a very good approach to work on a revision to fill this gap and provide clear rule to avoid any dispute across the supply chain.
The proposed revision specifies two categories of FIBC and proposes two different methods to be applied to:
Method A applies to FIBC for indoor storage
This is the same procedure which has been currently applied, namely accelerated test using UVB 313 lamp, test specimen needs to be exposed to a test cycle including UV lamp irradiation for 8 h at 60 °C followed by 4 h at 50°C with condensation and without UV. The new method applies a total test duration of 200 h whereas the current method considers 300 h for all FIBC types without any differentiation between in- or outdoor storage.
Method B applies to FIBC for outdoor storage
The revision proposes 3 alternative methods to be applied:
- Accelerated test with UVB 313 lamp in the same manner as in Method A for a total duration of not less than 1000h.
- Sunshine carbon arc lamp method, using a weather meter, test specimen needs to be exposed to a test cycle including irradiation for 102 min and both irradiation and spraying for 18 min, test shall be repeated until a total of at least 1000 h has been reached.
- Xenon arc lamp method, using a weather meter, test specimen needs to be exposed to a test cycle including irradiation for 102 min and both irradiation and spraying for 18 min, test shall be repeated until a total of at least 1000 h has been reached.
Assessment and acceptance criteria
After completing the exposure, breaking load and elongation at break in accordance with ISO 13934-1 to be applied. The results to be compared with the results performed on another set of specimens that have been stored under dark, room temperature condition to the same test. The test result is considered as positive when the residual breaking force in % stay above 50%.
Comments
A revision of current standard is a good approach in creating a practical test method reflecting the real condition. However the current proposal fails this goal as the proposed test methods add additional problems rather than providing a practical solution. Following I would like to share my observation, based on results of a profound study which was initiated by EFIBCA.
➢ FIBC are industrial packaging for both transport and storage within a rough and uncontrolled industrial environment, they usually stay for a long time, usually up to 3 years in service for usage in- and outdoor. Dividing FIBC in two categories increases the number of specifications and SKU ́s dramatically and is against the current focus of stakeholders in striving for creating more standardized fabric types and FIBC.
➢ It is well known that UVB test doesn’t correlate with sunlight and representing an aggressive fraction of sunlight spectrum which doesn’t reflect the real outdoor situation. If we want to apply accelerated test then it is more logical to apply UVA as a new approach to amend the existing standard, this is the most relevant test method for product such as woven fabric (see Fig.1).
➢ A recent performed study of Efibca where I had the pleasure to assist as project manager showed a very good correlation of UVA with natural weathering in Florida. UVB test with a duration of 1000 h will overkill any FIBC even with a high UV stabilization and will create serious problems to producing industry. Setting such high UV stability means using high dosage of UV- additive and consequently increasing the cost dramatically and compromise overall quality of the fabric with major impact on production process. Results of aforesaid project are shown in Fig.2. it shows very clear that UVA 1200 h provide the best correlation with 12 Month Florida. One of the major finding of this project was that there is a high deviation in results between weft and warp tapes. But the good news is that despite a negative result of weft tapes in UVA 1200 h respectively 12 Months weathering in Florida, the FIBC produced out of the corresponding fabric were performed SWL 1000 kg/5:1 test positively. In this graphic R1 is a fabric which was set for 150 kLy whereas R2 represent a setting for 200 kLy, consequently the results for R2 was better than for R1.
➢ Carbon Arc lamSpWLdtoeestsing’tafrterfl1e2cMt otnhtehsrsetoarlagoeu. tdoor situation either, this because of high presentation of UVA fraction. Carbo Arc is mainly used in the automotive industry, lack of references for woven materials such as FIBC is another disadvantage of this method.
➢ Xenon Arc is for sure the most suitable and qualified method among all proposed methods in the revision draft as it offer the best simulation of full-spectrum sunlight available in an accelerated weathering test. The proposed duration of 1000 h representing 12 Month MiddleEurope whereas the standard setting in the FIBC industry provides a protection for 18 Month. Therefore the proposed method B for outdoor application doesn’t justify an implementation of this method under this circumstances and need to be reviewed based on real test results.
In summary, an update of the current standard is for sure the right approach and should be supported by stakeholder. The current proposal misses the point where an improvement needed as the concept is half-baked and doesn’t address the main issue namely proposing a fact-based alternative to the current UVB accelerated testing.