IS 4571:1977 is the Indian Standard (BIS) for aluminium extension ladders for fire brigade use. This standard specifies the requirements for materials, dimensions, manufacture, and performance testing of aluminium extension ladders designed specifically for fire brigade rescue and fire fighting operations.
Specification of Aluminium Extension Ladders for Fire Brigade use
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Design/Test Load (Horizontal Bending) | Proof load of 180 kgf (approx. 1.77 kN) for deflection test. | Design load of 750 lb (340 kg / approx. 3.34 kN). | NFPA 1931:2020 |
| Rung Spacing (Centre-to-Centre) | 250 to 300 mm | 280 mm to 300 mm | BS EN 1147:2020 |
| Heat Exposure Indicator | Not specified | Mandatory heat sensor labels rated for 300°F (149°C) are required. | NFPA 1931:2020 |
| Minimum Inside Width | Not less than 300 mm | Not less than 406 mm (16 inches) between side rails. | NFPA 1931:2020 |
| Rung Torque Strength Test | Not specified | Must withstand a torque of 1000 lb-in. (113 Nm) without permanent deformation. | NFPA 1931:2020 |
| Rung Material Specification | Prescriptive: e.g., Aluminium Alloy HE 30 WP conforming to IS:733. | Performance-based: Rungs shall be constructed of material that passes all tests and has a slip-resistant surface. | NFPA 1931:2020 |