SWL: SAFE WORKING LOAD - Maximum carrying weight of a big bag
The Safe Working Load (SWL) indicates the maximum safe loading weight of the big bag.
FIBC (Flexible intermediate big containers) are designed for a specific SWL.
Common SWLs are 500kg, 1000kg, 1200kg, 1250kg, 1500kg or 2000kg. The SWL is determined by the customer.
Often the safety work load is chosen to achieve a maximal load weight on a truck of 24 or 25mt.
SF: SAFETY FACTOR
The Safety Factor (SF) reflects the ratio of the actual strength of the bag versus the safe working load.
ONE WAY VERSUS MULTI TRIP BIG BAG
One way big bags:
Big Bags are usually used only one time. They are filled and sold to a customer where they are emptied.
Usually it is not economical to collect the FIBC afterwards or to ask the customer to return the empty bag.
Often FIBC are used in food industry where it would not be hygienic to reuse them. Sometimes the FIBCs are never emptied and serve as a permanent waste bag.
The Safety factor (SF) for one way FIBC is 5:1, meaning that the big bag did burst only after reaching five times its safety work load (SWL) in the test rig.
A 1000kg big bag did therefore burst on more than 5t load. A 2000kg big bag bursts after 10t load in the test rig.
One way big bags cannot be “repaired”. It is not allowed to reuse these big bags.
Multi trip big bags:
Sometimes a multi trip big bag is more economical than a single trip one.
This is usually the case when all big bags are emptied at the same place and can be easily collected.
Furthermore, it should not be a food big bag. In this case the big bags can be returned to the filling place and reused for a limited number of times.
These multi trip big bags are constructed stronger and achieve a safety factor (SF) of 6:1 which means that the big bag did burst after more than six times its safety work load (SWL) during testing. On multi trip big bags an additional multi trip label can be added to count the number of circles.
Of course multi trip FIBC cannot be used infinite times. However there is no rule how often they should be used.
Multi trip big bags cannot be repaired. Damaged multi trip big bags must not be used. It is not allowed to fill in different materials into the FIBC on its different trips.
CERTIFICATION OF SWL AND SF
All our FIBCs are tested either in house or certified by respected testing institutes. The certificates name the safe working load and the safety factor.On request we will deliver the test reports for your FIBC.
Safe Working Load (SWL)
Single Trip SF