IS 939

: 1977

Specification for Snatch Block for Use with Fibre Rope for Fire Brigade Use

CurrentSpecializedSpecificationFire Safety · Fire Fighting
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This standard lays down the specifications for materials, dimensions, workmanship, and testing of snatch blocks specifically designed for use with fibre ropes. It is primarily used by fire brigades for rescue and general lifting operations.

Specification for Snatch Block for Use with Fibre Rope for Fire Brigade Use

Quick Reference Values
Proof load test2 x Safe Working Load (SWL)
Minimum factor of safety4 for load-bearing components
Sheave groove requirementMust be smoothly machined to prevent abrasion of fibre rope
Practical Notes
Always ensure the snatch block sheave groove size matches the specific diameter of the fibre rope to prevent rope flattening or excessive wear.
Verify the locking pin or mechanism is fully engaged before applying any tension to the rope.
Do not use snatch blocks specified under this standard with steel wire ropes, as the sheave material and groove profile are only rated for fibre ropes.