When demanding lifting capacity, extended span requirements, and uncompromising safety in explosive atmospheres converge, the LHB Type Explosion-Proof Hoist Double Girder Bridge Crane emerges as the engineered solution. This robust crane integrates the structural strength of a double girder design with intrinsically safe explosion-proof (Ex) components throughout, enabling reliable and compliant heavy lifting in Zone 1/21 and Zone 2/22 hazardous environments found in petrochemical plants, pharmaceutical facilities, grain processing, paint shops, and chemical storage.
Superior Load Capacity & Span: The double girder construction provides exceptional rigidity and strength, enabling capacities typically from 5 tons to 100+ tons and spans exceeding 35 meters – capabilities often beyond the reach of single girder explosion-proof cranes.
Comprehensive Explosion Protection: Every component posing an ignition risk – hoist motor, travel motors, control panels, limit switches, pendant stations, wiring systems – is housed within certified Ex d (flameproof), Ex e (increased safety), or Ex i (intrinsic safety) enclosures, preventing sparks or hot surfaces from igniting surrounding flammable gases, vapors, or dusts.
Enhanced Stability & Precision: The double girder design offers superior hook height (maximizing usable lift under the crane) and load stability during travel, crucial for precise placement of heavy or sensitive loads in critical areas. Optional frequency-controlled drives (VF) ensure smooth, jerk-free starts and stops.
Robust Duty Cycle (A5-A7): Built for heavy and very heavy-duty applications common in industries like bulk handling (with grabs) or production lines, far exceeding the typical duty of single girder explosion-proof models.
Flexible Control & Monitoring: Operators use certified Ex d or Ex i pendant controls or explosion-proof radio remote systems. Integration of load moment indicators (LMI) and anti-collision systems is standard for enhanced safety.
*Table 1: Key Explosion-Proof Components & Ratings*
| Component | Essential Protection Method | Typical Certification/Standard | Critical Function |
|---|---|---|---|
| Main Hoist Motor | Ex d (Flameproof Enclosure) | Ex db IIC T4 Gb / Ex tb IIIC T135°C Db | Provides primary lifting power; contains internal explosion. High temp. rating (T4/T135°C). |
| Trolley/Travel Motors | Ex d or Ex e (Increased Safety) | Ex eb IIC T4 Gb / Ex tb IIIC T135°C Db | Drives trolley across bridge and crane along runway. Ex e focuses on preventing sparks. |
| Control Panel | Ex d (Pressurized Purge ‘p’ sometimes used) | Ex db IIC T4 Gb | Houses contactors, relays, VFDs. Prevents internal arcs/sparks from igniting atmosphere. |
| Pendant Control Station | Ex de (Combined d & e) or Ex i (Intrinsic Safety) | Ex de IIC T4 Gb / Ex ib IIC T4 Gb | Operator interface. Ex i limits energy to non-incendive levels. |
| Limit Switches | Ex e or Ex i | Ex eb IIC T4 Gb / Ex ib IIC T4 Gb | Prevents over-travel of hoist, trolley, bridge. |
| Cable Reels/Feeding | Ex e Components & Special Cable | Ex eb IIC T4 Gb | Supplies power to crane/trolley; uses special sheathed, non-sparking cable guides. |
| Wiring | Mineral Insulated (MI) Cable or Equivalent | Compliant with IEC/EN 60079-14 | Highly durable, fire-resistant wiring maintaining circuit integrity in harsh conditions. |
*Table 2: Hazard Zone Suitability & Gas/Dust Groups (Typical LHB Rating)*
| Hazardous Area Zone | Definition | LHB Suitability | Target Gas Group / Dust Class |
|---|---|---|---|
| Zone 1 / 21 | Explosive atmosphere likely during normal operation | SUITABLE | Gas: IIC (Hydrogen, Acetylene) / IIB (Ethylene) |
| Zone 2 / 22 | Explosive atmosphere unlikely & short duration | SUITABLE | Dust: IIIC (Conductive) / IIIB (Non-Conductive) |
| Zone 0 / 20 | Explosive atmosphere continuously present | NOT SUITABLE | Requires specialized equipment beyond standard Ex d/e/i. |
Capacity Range: 5t, 10t, 16t/20t, 32t, 50t, 63t, 80t, 100t+ (Customizable)
Span Range: 10m – 40m+ (Adapted to building structure)
Lifting Height: 6m – 30m+ (Determined by facility)
Work Duty Class: A5 (Heavy) / A6 (Very Heavy) / A7 (Extreme) – Matched to hoist spec.
Hoisting Speed: 0.8 – 15.3 m/min (Often dual-speed; VFD control common)
Trolley Speed: 5 – 20 m/min (VFD controlled for precision)
Crane Speed: 10 – 32 m/min (VFD controlled)
Power Supply: 3P, 380V, 50Hz (Standard); 415V, 480V, 60Hz options available.
Ambient Temp: -25°C to +40°C (Special designs for wider ranges possible).
Protection Class: IP55 / IP65 (Dust/Water Jet Protected) standard; IP66 for harsh washdown.
Control: Explosion-Proof Pendant (Standard), Explosion-Proof Radio Remote (Highly Recommended), Cabin Control (Possible with Ex-rated cabin).
Oil & Gas Refineries: Handling catalysts, reactor internals, valves, pipes in processing areas.
Chemical & Petrochemical Plants: Lifting drums of solvents, intermediates, bulk powders (e.g., polymers), reactor vessels.
Pharmaceutical Manufacturing: Moving flammable solvents, powdered active ingredients (APIs), large bio-reactors in classified areas.
Grain Silos & Flour Mills: Handling grain, flour, starch in silos or processing areas prone to combustible dust explosions (Dust Group IIIB/IIIC).
Paint & Coating Facilities: Lifting large tanks, mixers, or finished products in spray booths or areas with solvent vapors.
Aerospace & Defense: Servicing fuel tanks, handling rocket propellants or volatile components.
Bulk Handling (with Ex Grab): Transferring coal, biomass, or other combustible bulk materials in hazardous zones.
The LHB design prioritizes safety beyond explosion protection:
Overload Limiter: Mandatory protection against exceeding rated capacity.
Dual Braking Systems: Primary (electromechanical) + secondary (mechanical or regenerative) braking on hoist and critical motions.
Redundant Limit Switches: Upper/Lower hoist limits, trolley/bridge end limits (multiple sets).
Emergency Stop Circuits: Hard-wired E-Stop buttons on pendant/remote, accessible on crane.
Anti-Sway System (Optional): Essential for precise load control, especially with long lifts.
Compliance: Adheres to stringent international and national standards:
ATEX Directive 2014/34/EU (EU): Essential for European market.
IECEx System (International): Globally recognized certification.
GB3836 Series Standards (China): Core standard for Ex equipment.
NEC / CEC (North America – Class I Div 1/2, Class II Div 1/2): Requires specific UL/FM approvals.
FEM 1.001 / ISO 8306: Structural design standards.
Expert Installation: Requires specialized technicians familiar with Ex equipment installation standards (e.g., IEC/EN 60079-14). Correct earthing/bonding is critical.
Strict Inspection Regime: Daily operator checks, frequent inspections by qualified Ex personnel, thorough periodic inspections per regulations (e.g., annually). Focus on integrity of Ex enclosures, cable glands, and seals.
Ex-Specific Maintenance: Only certified Ex repair facilities using OEM-approved Ex components can perform repairs to maintain certification. Detailed records are mandatory.
Operator Training: Comprehensive training on safe operation in hazardous areas, understanding zone classifications, emergency procedures, and specific hazards of the crane/load.
Lifecycle Management: Factor in the higher initial cost and specialized maintenance requirements against the critical safety benefits and operational necessity in hazardous environments.
The LHB Type Explosion-Proof Hoist Double Girder Bridge Crane represents the pinnacle of safe and powerful material handling for hazardous environments. By combining the robust structural advantages of a double girder crane with rigorously certified explosion-proof technology across all potential ignition sources, it enables heavy and precise lifting operations in areas where standard equipment poses an unacceptable risk. Investing in an LHB crane is not merely an equipment purchase; it’s a fundamental commitment to operational safety, regulatory compliance, asset protection, and personnel well-being in industries where flammable hazards are inherent. For critical lifts demanding both high capacity and intrinsic safety, the LHB crane delivers unmatched reliability and peace of mind.
