Load cells have long been a ‘go to’ solution for weighing loads lifted by crane. The technology is proven, reliable and robust, especially important in demanding dockside, shipping and marine environments.
An interesting article in January’s Hoist magazine outlines the role of load cells in lifting technology, and how the way data gathered by the load cells is being used to provide more information, more quickly, to more people.
Load weights: accuracy is key
Knowing the exact weight of a load before lifting is crucial. This is not just in the interests of safety when lifting, but also for the safety of the equipment itself. With a tendency for modern loads to be heavier than ever before, lifting equipment may be operating close to their upper limits. This in tun has an effect of the working lift of the equipment over time. This is where recording and storing data from load cells comes into its own.
At the time of lifting, it’s standard practice these days for data transmitted by wireless load cell units to be sent to a handheld digital monitor. This unit presents the data in real time, enabling operators to watch load weights during all stages of the lift. Many units allow an audible alarm to sound if loads are close to the maximum load limit, so all involved in the lift can take extra precautions.
By downloading the stored data to a PC or laptop (or indeed relaying directly), the number of alarms and the exact weights lifted can be stored and analysed. This builds an audit trail of usage, and allows operators and owners alike to spot possible patterns and review their maintenance or replacement schedules.
Monitoring shifting load weights on the ground
When a load is lifted, it might distort or shift, making absolutely accuracy from second to second difficult to assess. This is where compression load cells can help. Positioned under the load on the ground, the load can be lowered onto the load cells, allowing the load to settle and a more accurate reading taken.
Slings and shackles: load cells flying high
The comparatively low cost of load cells has enabled operators to use more of them, for more accurate data. So, where previously a load lifted using slings and a spreading bar might have had a singlet load cell in the central shackle, now each sling can have its own load cell to measure the tension during the lift. Data from all load cells involved can be relayed to a central unit, where software can then accurately calculate the load’s central gravity. The result is level lifts and safer working environments.
Many units make light work
One of the big advantages of wireless load cells is the ability to send data to several handsets or units at the same time. So, where previously data from cabled load cells would end up being seen by only one person, now multiple users can see that data at one time, including the crane operator high above the dock, a supervisor, and their colleagues below.
As Niels ven der Bruggen, business development manager of Lifting Gear Hire (LGH), explains:
“Wireless connections, strong Wi-Fi signals, user-friendly software and powerful computers are becoming more mainstream within the lifting industry. That affects the way we work and the equipment we use. It is not a replacement to previous methods but an addition.”
Compliance with SOLAS requirements
This ability to relay information quickly and reliably will also help with compliance for the amended SOLAS requirement for packers, shippers and logistic companies to declare the weight of their shipping containers before they are booked onto a container ship.
“The International Maritime Organization (IMO) has amended the Safety of Life at Sea Convention (SOLAS) to require, as a condition for loading a packed container onto a ship for export, that the container has a verified weight. The shipper is responsible for the verification of the packed container’s weight. This requirement will become legally effective on July 1, 2016. After that date, it would be a violation of SOLAS to load a packed container onto a vessel if the vessel operator and marine terminal operator do not have a verified container weight.”
This is to avoid uneven loads that could cause a ship to list, lose cargo and potentially be overloaded. By weighing the container at the point where it is first lifted, i.e. at the shipper’s depot, the data can be logged and presented before arrival at the dockside.
Lifting load cells and load links
If you’re looking for wired or wireless solutions for lifting, take a look at our range at our online shop. Or let us take the strain and call us to discuss your particular requirements.