Load cells: Everything you need to know
What is a load cell?
A load cell emits an electrical signal that strengthens in response to a detected force, enabling you to understand the load exerted onto it. There are various types of load cells, including strain gauge load cells, pneumatic load cells, hydraulic load cells, piezoresistive loads cells, and magnetorestrictive load cells. In industrial environments, strain gauge load cells are the most widely established load monitoring method as they offer increased accuracy and cost-efficiency compared to the other options.
Why are load cells used?
Load cells are used to understand the loads that assets experience within a wide range of sectors, from construction and industrial manufacturing to commercial shipping and oil and gas. While their specific benefits mainly depend on their application, load cells are typically deployed to increase the safety and performance of assets.
To help protect your operations, load cells will alert you if the force exerted onto an asset exceeds its safe working capacity. You can also use load data diagnostically to determine whether an asset is handling loads as intended, which helps to maintain a safe working environment by mitigating the risk of structural integrity incidents. Lift testing, fatigue analysis and container weighing are just some of the safety-related operations that load cell technology enables.
Through real-time load monitoring, the most advanced load cells also deliver data insights that help to optimise the efficiency of your operations. Load data is critical to a host of performance enhancing operations, including model verification, value engineering, asset lifecycle extension, and predictive maintenance.
Different operations need varying levels of instrumentation to enable effective load monitoring. Recognising this, Strainstall can accommodate any pre-set configuration or project size. Depending on your requirements, our solutions range from the supply of individual load shackles and load pins, to full-scale load monitoring systems.
What are hazardous area load cells?
Hazardous areas explained
In industries such as mining and oil and gas where flammable gasses present a continuous threat, hazardous areas are predefined to help ensure the safety of onsite personnel. An area is described as hazardous if there is a possibility for explosive gasses to exist in normal operation.
The ATEX and IECEx directives enforce the following hazardous area categorisations for equipment use, which vary depending on the prevalence and persistence of flammable gasses:
Zone 0: An area where explosive gasses are present continuously and for long durations.
Zone 1: An area where explosive gasses are likely to be present, but only persist intermittently.
Zone 2: An area where explosive gasses are unlikely to be present, but have the potential to persist for short durations.
Non-hazardous area: An area where no explosive gasses are expected to be present.
Other hazardous area global directives are available which are similar to ATEX and IECX above.
Hazardous area load cells
For a load cell to be considered hazardous area certified, it must mitigate the chance of ignition in all elements of its design. The tolerance level for this heightens depending on the device’s zone classification.
Featuring specially designed wireless handsets that mitigate the risk of ignition if dropped, Strainstall offer a range of Zone 1 and Zone 2 certified load cells to meet your hazardous area needs.
Hazardous area and explosion-proof: What’s the difference?
As they are both designed for safe use in flammable environments, hazardous area certified equipment is often confused with explosion-proof devices. However, the way that they increase safety differs significantly. While hazardous area certified equipment minimises the chance of any ignition within its design or circuitry, explosion-proof equipment contains potential detonations within an enclosure, sealing it away from the flammable environment. It is important to note that explosion-proof equipment is not designed to be resistant to external explosions.
What is load cell calibration?
A calibration tests the accuracy of load cells against a pre-set standard. As a load cell’s measurement accuracy typically decreases as its age increases, it is good practice to have it regularly calibrated – particularly when deployed in high-assurance sectors such as oil and gas. While ISO9000 mandates the calibration of load cells every 18 to 24 months, it is widely recommended that calibrations should be performed every year to maximise safety.
Need to calibrate your load cells? We offer a range of calibration services to meet your requirements. Unlike other services on the market, our specialist in-house facilities can accommodate load cells of all shapes and sizes without the need to outsource equipment, saving you time and money.
What is load cell resolution?
Resolution determines how accurately a load cell can produce a measurement when detecting a change in force. This is different to load cell sensitivity, which is the minimum force that a load cell can identify. The resolution you need depends on the application, but as a benchmark, the resolution of strain gauge load cells is typically between 0.03% - 0.25% of full scale.
While most operations do not require more than 0.25% of full scale, we offer bespoke load cells with higher resolutions on request. Contact us to learn more.
Direct and indirect load monitoring: What's the difference?
Direct load monitoring devices are fitted within the primary load path to directly measure the load exerted on shackles, pins and other equipment types. On the other hand, indirect systems determine load by measuring its results from outside the primary load path. For many applications, there are significant advantages to using indirect monitoring technology. As indirect measurement avoids the primary load path, it is more cost-effective when monitoring loads upwards of 100 tonnes - which would otherwise require the costly manufacturing and transportation of heavy-duty equipment.