Overview
ISO 9851:1990 - "Continuous mechanical handling equipment - Overhead electrical monorail conveyors - Definitions and safety rules" defines basic terms and sets safety requirements for overhead electrical monorail systems used for materials handling. The standard covers the rail, supporting structure, lifting/lowering sections, trolleys (motorized and non-motorized) and load‑supporting devices. It does not apply to hand‑driven or gravity‑driven systems, systems conveying people, or certain aerial conveyors.
Keywords: overhead electrical monorail conveyors, monorail safety rules, continuous mechanical handling equipment, materials handling standard.
Key topics and technical requirements
- Definitions and terminology: Clear definitions for components such as monorail, trolley (chariot), mobile assembly, rail, lifting section and load‑support device help ensure consistent interpretation across design, installation and maintenance.
- Design and construction:
- Trolleys must be designed to avoid derailment or falling if a component fails.
- Couplings on motorized trolleys must prevent accidental decoupling of non‑motorized units.
- Lifting devices must comply with applicable lifting‑equipment rules.
- Identification and markings:
- Each mobile assembly must be unambiguously identified.
- Maximum permitted payload (including removable load supports) must be visibly indicated on each mobile assembly.
- Guarding and protection:
- Protect crushing, shearing and entrapment points in work and circulation zones.
- Where monorails operate over personnel areas, design must protect people from overturning loads or falling objects.
- Safety distances and clearances (examples specified):
- Minimum lateral clearances: 0.8 m in work and circulation zones; 0.6 m (reducible to 0.5 m near short obstacles) in occasional access routes.
- Vertical/clearance limits: 0.12 m between floor and mobile assemblies; 0.5 m above occasional access zones; 2.5 m when monorail passes over permanent workstations or pedestrian routes.
- Maintain at least 0.5 m spacing between mobile assemblies up to 2 m height in accessible motion zones.
- Controls, isolation and electrical safety:
- Emergency stops, secure isolators (lockable sectioning), and compliance with electrical protection rules (IEC/CEI references) are required.
- Where track speed or visibility creates risk, traffic‑control or warning devices (optical/acoustic) are advised.
- Installation, commissioning and maintenance:
- Systems must allow individual stopping of mobile assemblies; procedures for safe isolation/lockout and safe access for maintenance are mandatory.
- Personnel must be trained and informed of hazards and restricted access areas must be signposted.
Applications and users
ISO 9851 is intended for designers, manufacturers, plant engineers, safety officers, installation contractors and maintenance teams involved with overhead electrical monorail conveyors in factories, warehouses and process plants. It provides practical rules for safe design, installation, operation and servicing of monorail materials‑handling systems.
Related standards
- ISO 1819 (safety code for continuous handling equipment)
- ISO 6385 (ergonomic principles for work‑system design)
- IEC/CEI 144 and CEI 364 (electrical protection and building electrical installations)
Use ISO 9851 to ensure consistent terminology, implement required safety distances and protective measures, and align overhead monorail systems with recognized international safety practice.