What are maximum capacity ratings?
You can probably think of a product that contains a mark reading “Maximum capacity ___ lbs”. Have you ever wondered how capacity ratings are determined? These ratings are the result of testing that consists of loading or filling the product until it tears, sinks, buckles or falls. Manufacturers perform these tests to determine the amount of weight a particular product can safely support.
Capacity Ratings
Proof Testing
“Proof testing” is a series of repeated tests, performed at set capacities, that determine whether or not a product has proven to be effective at those capacities. The testing ensures that a product can safely support the same amount of weight over & over again.
Repeatability is key in safety & quality control testing. For instance, in the J&M Industries snow tarpaulin video below, lift tests were repeated 30 times at predetermined target weights. If the tarpaulins withstand the repeated testing, then J&M Industries can confidently establish a capacity rating. The proof testing process helps to ensure products are safe, reliable & ready for use.
What tools are required to perform proof tests?
Measurement equipment is required to perform proof testing. The final application of the product being tested determines the measurement discipline and the type of measurement equipment required. Michelli Weighing & Measurement companies are capable of conducting proof testing in the disciplines of weight, mass, force, torque, pressure, temperature, dimensional, electrical & frequency measurement.
Those products that will be used in lifting applications, such as nets & tarpaulins, require force measurement equipment to conduct testing. In the video below, snow tarpaulins are being lifted, so force measurement testing is required. Michelli used a Dillon dynamometer with a 25K lb capacity to perform the tests. The dynamometer attaches to both the crane & the object being measured, which in this case is a snow tarpaulin. The dynamometer measures the tension created by the pull of the object as it is suspended from the crane. This measurement is displayed in lbs on the dynamometer itself, and on a remote display.
25K Dillon Dynamometer with remote display
Why did this product require proof testing?
Construction crews throughout the Northern United States cover their work sites with these snow tarpaulins at the end of each day. The snow tarpaulins help protect the site & equipment against overnight snowfall. In the morning, the crews use a crane to remove the tarpaulin full of snow. J&M Industries manufactures the snow tarpaulins & needed to establish capacity ratings to determine how much weight each tarp can safely hold. These ratings, coupled with the amount of snowfall, help the construction crews judge whether it is safe to remove the tarpaulins. If the amount of snowfall exceeds the maximum capacity, the crews wait for the snow to melt a bit prior to tarp removal.
Watch the video below to find out how a company in Southeastern Louisiana tests snow tarpaulins to maximum capacity with force measurement.
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