Fire Fighting & Safety Traning Institute | NIIFS

To calculate the SWL in kilograms of FSWR square the rope diameter (D) in millimetres (mm) and multiply by 8.
Formula: SWL (kg) = D2(mm) x 8
For example:
Rope dia (D) = 12 mm
SWL(kg) =D2 (mm)x8
= D (mm) x D (mm) x 8
= 12 x 12 x 8
= 1152 kg SWL (t) = 1.15 tonnes
The above equation can be reversed to calculate the diameter (D) in millimetres of FSWR needed to lift a given load. To do this, divide the load (L) in kilograms by 8 and find the square root of the result.
Formula: D(mm) = √L(kg) 8
For example:
Load = 1152 kg
D (mm) =  1152 ÷ 8 = √144
= 12 (mm)
Therefore a FSWR sling of at least 12 mm in diameter is required to lift a 1152 kg load for a straight lift.

NIIFS, Fire Safety and Traning Institute

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