Be Careful About Relying on Magnetic Sweeper Strength Ratings, or Magnetic Field or Flux Density Quantifications
We get asked sometimes “what grade are your magnets” or “can you tell me the field or flux density of your magnetic products”.
In other words customers want specific information in regards to magnetic sweeper strength, some objective straight forward measurement they can compare from manufacturer to manufacturer. And this is completely understandable. But unfortunately, it really can’t be done, and here’s why.
The different series sweepers do vary in terms of “pickup power”. Pickup power is a very difficult thing to explain or for a potential buyer to ask about and still have it mean anything. This is why Bluestreak measures pickup power in terms of the “maximum lifting height using a two and half inch nail”. Everyone knows what a two and a half inch nail looks like. This measure indicates the maximum height that the sweeper can pick up a two and half inch nail from in a bench test.
This is the best indication of performance. We don’t provide a Gauss field measurement (Gauss: the cgs unit of magnetic induction) because Gauss is the most misunderstood term in magnetics, greatly misused by some manufacturers who use the manufacturer’s Gauss rating to indicate the strength of their products, when in truth the strength of a magnet depends on:
a) Strength of the material (manufacturer’s Gauss rating)
b) Size and weight of the magnet
For example: The earth’s magnetic field is 0.5 Gauss and a refrigerator magnet is 10 Gauss.
Considering only these numbers one would think that a refrigerator magnet is more powerful than the earth. This of course is incorrect, the earth, due to its immense size is immeasurably more powerful.
Unfortunately there is no standard mathematical formula to calculate the strength of a particular magnet.
We also don’t measure “strength” of a magnet in terms of the “weight” of steel it will pick up, because it matters what the form of the object is that is being picked up. A steel bar is dense and you can pick up a lot more weight in terms of a steel bar, than you can nails, etc.
We therefore had to come up with a way of communicating magnet strength that everyone would practically be able to relate to and understand, which is why we use the “maximum lifting height using a two and a half inch standard nail”.
It may be good to know that not everyone selects the most powerful magnet. There can be some good reasons for doing so but if you’re a mobile contractor like a roofer, many roofers want something light that they can put behind the seat of their pickup truck. They don’t have to clean a very large job site normally and if they have to pass over an area several times with a smaller magnet that’s acceptable to them.
Therefore take a close look at all the features, some magnets have a very easy auto debris release lever to make clean off easy, others have lots of wheel hole settings to make fine tuning sweeping height easy for your normal application.
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