| Bathroom Scale |
| There are many models and features to choose from, but it doesn’t have to be a confusing and frustrating process if you can define your needs and match them with the proper scale. |
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| Body Mass Index - BMI |
| The body mass index - BMI is an approximate measure of body fat. It is based on your height and weight. |
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Many countries regulate the design and servicing of scales used for commerce. This has tended to cause scale technology to lag behind other technologies because expensive regulatory hurdles are involved in introducing new designs. Nevertheless, there has been a recent trend to "digital load cells" which are actually strain-gage cells with dedicated analog converters and networking built into the cell itself.
Government regulation generally requires periodic inspections by licensed technicians using weights whose calibration is traceable to an approved laboratory. Scales intended for casual use such as bathroom or diet scales may be produced, but must by law be labelled "Not Legal for Trade" to ensure that they are not repurposed in a way that jeopardizes commercial interest.
Because gravity varies by over .5% over the surface of the earth, the issue of "weight" vs. "mass" becomes relevant for accurate calibration of scales for commercial purposes. The goal is to measure the weight (actually, the mass) in relation to the legal reference standards (not the true scientific local weight at that particular location).
Traditional “doctor’s office” balance-beam scales measure weight using a pressure spring movement in relation to movable sliding weights. The tension of the spring can change over time, giving incorrect measurements over an extended time or frequent use. Modern digital electronic scales that use load cells give an accurate and repeatable measurement that will not change over time or frequent use. Digital scales can be calibrated on-site for optimal accuracy.
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