A crane like a gantry crane is a significant investment, but the right piece of equipment can pay itself back many times over by delivering increased safety, efficiency and productivity to your workplace. So how do you ensure the crane you choose is fit for purpose?
With crane duty classifications.
In this guide we’ll cover all you need to know about crane duty classifications: what they are, which apply in New Zealand, and how to use them to ensure your crane can do what you need it to.
What are crane duty cycle classifications?
Imagine two customers who are in the market for a power drill. The first is a homeowner who wants to hang a couple of picture frames and who knows a drill is a handy tool to have in the shed. The second is a professional builder who spends entire days screwing materials together.
These two customers will put their drills through very different ‘duty cycles’: the extent and intensity of use. As such the builder would be wise to look for a more powerful, heavier duty tool than the homeowner.
Crane duty classifications are designed to make this choice clear for anyone looking to invest in a crane. They categorise cranes by the frequency and severity use: the percentage of the day they are functioning and the percentage of the crane’s working load limit (WLL) they will function at.
Why are crane duty classifications important?
Crane classifications form a simple way for buyers and suppliers to understand the working conditions a free standing jib crane will face. This information informs design, construction, material choice and more.
If you don’t work to understand the duty cycle of your prospective crane purchase, you risk:
- Choosing an over-engineered crane that costs far more than it needs to, and that offers capabilities that you’ll never utilise.
- Choosing a crane that isn’t designed for the intensity of the work that it needs to do, leading to lower efficiency and productivity, and potential safety issues for your team members.
Crane duty classifications ensure that your new crane investment is a wise one – that it will be capable of doing the job you’re buying it for.
Which crane duty classification applies in NZ?
A number of crane duty classifications exist across the globe. In New Zealand we don’t use a single classification system – how a piece of lifting equipment is classified will depend on where it is manufactured.
That said, most crane duty classification systems take a similar approach, dividing cranes, including portable hoist cranes, into a handful of different categories based on time and working load limit (WLL) considerations, ordered from lightest duty to heaviest duty.
The most common crane duty classification system used in New Zealand is the European FEM system. To classify your crane, you must first identify the applicable load spectrum: light, medium, heavy or very heavy.
After determining your expected load spectrum, you need to determine the expected daily operating time of your crane, using the following equation:
Daily operating time = (2 x H x N x T) / (V x 60)
- H = Hoisting height (average in metres)
- N = Number of hoisting cycles per hour
- T = Time in operation per day (in hours)
- V = Hoisting velocity (metres per minute)
You can then use the table below to find your required FEM classification.
As you can see on this table, the FEM classification system aligns with the ISO crane duty classification system. The only difference is in the names of the categories: an FEM 1Am category crane is equivalent to an ISO M4 category crane.
What are other types of crane classifications?
Four main crane duty classification systems exist across the globe, and ultimately the classification that applies to your New Zealand crane will depend on the brand that manufactures it.
Along with the European FEM classification, North America has three separate classifications: ASME, HMI and CMAA. These classifications take a similar approach to FEM, calculating time and weight considerations to categorise cranes across a spectrum. ASME, for example, splits cranes into five basic categories:
- H1: Standby/infrequent usage.
- H2: Light service.
- H3: General service (used up to 25% of the day).
- H4: High volume of heavy loads.
- H5: Heavy to continuous service.
These classification systems tend to stay the same across all types of cranes: tower crane duty classification systems and overhead crane duty classification systems are one and the same.
It’s important to speak to your crane supplier to understand which classification system applies to their cranes, and the specific category that your required lifting hoist will sit within.
Enabling New Zealand businesses to work smarter, quicker and safer
Crane duty classification systems can feel complex, even overwhelming; particularly for those who don’t spend much time dealing in lifting equipment.
But identifying the appropriate crane classification is critical if you want to work safely and productively, while also ensuring you don’t overspend on surplus capability. By finding the right classification you greatly increase the chances of getting the ideal crane for your situation.
At Stratalign we’ve spent years helping Kiwi businesses identify and secure the lifting equipment that will get them working smarter, faster and safer. If you’re looking to enhance your operations with lifting equipment that does exactly what you need it to do, get in touch with our expert team today for a no-obligation consultation and quote.
