Lifting heavy loads is an integral yet potentially hazardous task across many industries, including construction, manufacturing, shipping, and more. However, crews can conduct lifts safely and efficiently by utilizing precise load measurement equipment like crane scales combined with proper procedures. These heavy-lifting devices are at the heart of susceptible load cells, enabling accurate weight data to inform safe operating parameters.
What are Load Cells?
Load cells are specialist transducers that convert a physical force, such as tension or compression from a crane or hoist line, into an electrical signal proportional to the load. This analog signal connects via cabling to indicating and monitoring instruments.
How Do Load Cells Work?
Using a strain gauge-based Wheatstone bridge configuration bonded to a metal core, minute mechanical distortions from applied loads alter electrical resistance indicating the load’s weight as small mV signals. Robust constructions protect measurement integrity from sideload effects while allowing straightforward integration into lifting equipment.
Types of Load Cells for Crane Scales: Choosing the Right Fit
Selecting the appropriate load cell for a specific crane scale application is essential for optimal performance and safety. Here are some common types of load cells used in crane scales, each with its unique characteristics:
S-type load cells:
S-type load cells have a dual-ended shear beam design that measures either crane hoist tension or vertical compression from overhead lifting. Their S-shape allows load introduction from multiple directions, making them one of the most versatile options.
Compression load cells:
Exerting force axially along the cell’s vertical axis, compression load cells are extremely robust for weighing stationary vessels and tanks. They easily handle eccentric loading without losing accuracy.
Tension load cells:
Tension load cells measure inline tension forces from hoist lines or lifting gear. The load cell’s cable termination hardware connects to the crane’s hook or other lifting tackle.
Bending beam load cells:
Bending beam load cells use strain gauges on a flexible beam, which deforms slightly as side forces are applied to the hook attachment point. This style offers reliable readings on off-axis pulls.
Factors to consider when choosing a load cell for a crane scale include:
Choosing the right load cells for crane scales for your specific construction needs requires careful consideration of several factors:
- Capacity: Selecting a load cell with a capacity rating between 100-125% of your expected load requirements allows room for unexpected additional loads while maintaining high precision. Passing maximum load cell ratings risks damaging cells permanently, leading to dangerous failures.
- Accuracy: Load cells meeting 0.03% accuracy grades or better provide reliably repeatable weight readings well-suited for most lifting applications without breaking budgets. Higher accuracies to 0.015% are available for precision applications needing exact load control.
- Environmental conditions: Load cells fitted with rugged IP67 and IP68-rated protective seals maintain measurement integrity in harsh, heavy wash-down areas and wide temperature swings encountered outdoors. Choose corrosion-resistant designs where caustic chemicals or saltwater is present.
- Output signals: Digital outputs like precise 16-bit CANbus or industrial Ethernet interfaces ensure data completeness over long runs, unlike analog signals. Such digital signals also enable telemetry metrics for remote site monitoring.
- Approvals: Select load cells meeting approval standards like ATEX for intrinsically safe operation in explosive environments or look for hazardous area FM approval for North American compliance assurance.
The Benefits of Using Load Cells in Lifting Operations
Implementing load cells in lifting operations offers a multitude of benefits, including:
Enhanced safety:
Load cells continuously supply weight data through the lift to prevent dangerous overloading by keeping crane operators constantly informed of loads approaching on hoist lines. Preset adjustable overload alarms provide alerts before reaching equipment failure limits to avert disasters.
Improved efficiency:
By providing accurate real-time weight measurements to equipment operators, cranes haul optimized payloads per lift without wasted time or fuel lifting unknown payloads. Weight tracking helps balance asymmetric loads, preventing dangerous side stresses.
Minimized downtime:
Modern load cell diagnostics can quickly identify potential issues through live trouble codes, allowing preventative maintenance before catastrophic failures cause expensive operational shutdowns and jeopardize projects.
Accurate data collection:
Detailed records from high-resolution load cell measurement data determine cost allocations precisely and highlight usage patterns to refine practices and provide accountability.
Increased productivity:
Eliminating manual weighing steps and enabling optimized material handling translates directly into substantial productivity gains across cargo loading/unloading workflows measured through Industry 4.0 key metrics.
Remote Monitoring:
Networked load cell digital outputs let site managers proactively monitor multiple cranes’ rigging loads and usage remotely through plant-wide telemetrics rather than solely relying on periodic error-prone manual data recordings by operators at the shift’s end.
Considerations for Safe and Efficient Lifting Operations
While high-quality crane scales and load cells are crucial in enabling safety and efficiency during lifts, it is important to remember that they comprise just one part of a mature, comprehensive lifting safety management plan. Additional elements include:
Regular maintenance:
Scheduled verifications, cable inspections, alignment checks, and recalibrations on both load cells and overall lifting gear are imperative to ensure continued weighing accuracy and prevent dangerous wear issues before failures. Keep detailed maintenance logs.
Proper operator training:
Qualified operators understand correct equipment unfolding/setup procedures, leveling, load chart reading, overload hazards, instrumentation use, and communications and maintain site safety. Classroom and hands-on training should cover normal procedures and emergency response.
Standardized lifting procedures:
Comprehensive written step-by-step lift plans optimize approach angles, boom positioning, tagline use, and gentle multi-point load take-up to prevent uncontrolled swinging or snatch shock overloads during placements. Audits ensure conformity.
Certified lifting gear:
Regular detailed inspections, along with current testing and certificates for all slings, shackles, hooks, sheaves, and lifting points, avoid failures leading to accidents. Retire worn equipment on schedules.
Incident investigation:
Perform root cause analysis on any incidents to identify process improvements across policies, training, procedures, and equipment/technology upgrades to incorporate lessons learned through a continuous improvement approach targeting zero lift accidents.
Safety culture reinforcement:
Senior management must visibly and consistently demonstrate lifting safety is a top priority through leading key initiatives, allocating resources to upgrade capabilities, and tracking progress on key safety performance indicators to drive cultural alignment.
Conclusion
By combining robust and precise load cells for crane scales with comprehensive safe lifting plans encompassing training, procedures, and certified gear, lifting operations can maximize productivity and minimize costly downtime accidents across nearly all industries where heavy loads are handled. Trusted manufacturers provide high-quality, long-lasting load cell solutions to meet any lifting capacity need while delivering the weight data fidelity crane operators require for precision lift optimization.