01980 625452

Copyright © All rights reserved

Terms of Use |

Privacy Policy |

Customer Service

If you don’t see it here

We’ll find it for you

How do I calculate my BMI? What does calibration mean? And why does one weigh more at the North Pole than at Kilimanjaro? Learn more about weighing here.

Adjustment or: Why does one weigh more at the North Pole than on Kilimanjaro?

An electronic scale measures the force with which a person is pulled by the earth. This force depends on location. It gets smaller and smaller the further the scale is from the centre of the earth. Therefore, a scale must be correctly adjusted for its location of use. Otherwise, a person who weights 80 kg at the North Pole would weight only about 79.1 kg on Kilimanjaro. Scales not adjusted for this difference in the earth's gravitational pull cannot be used in medicine, since every gramme nearly always counts in medicine. Before a SECA scale is delivered, it is precisely set for it future location of use.

What does calibration mean?

In the countries of the European Union, for example, scales and measuring instruments used in the medical field must be calibrated. The calibration is used to determine the error limits of a scale. The smaller the error limits, the more accurate and better the scale. A calibrated scale is therefore of greater value than an un-calibrated scale. Most SECA scales are available in calibrated and un calibrated versions.

What is the difference between a SECA scale and a scale from the supermarket?

What is the difference between a personal scale from the supermarket and a SECA scale? Both, for example, have the same number scale with a 1 kg gradation.

The difference is that the SECA scale displays the exact weight it measures. The scale from the supermarket shows the weight which only loosely corresponds to the actual weight. The supermarket scale is not very accurate. By the way, that applies to both mechanical and electronic scales.

Definition of accuracy acc. to DIN EN 60051

The accuracy of a scale is the degree of agreement between the displayed and correct value. It is determined by the intrinsic error limits and influencing effect limits. In other words, accuracy depends on the quality of the components, the quality of the load cell and environmental conditions. An environmental condition that affects accuracy can be the temperature or humidity. Under error limits for calibrated scales is understood the permissible tolerance, i.e. the permitted weight deviation by plus and minus. They are load sensitive and defined in the calibration regulations.

Definition of gradation

Gradation is the smallest possible readable distance between to weight values. For digital scales, it is identical to readability. For mechanical scales, it is the smallest weight value on a scale consisting of dividing lines and numbers that are read with a pointer or index.

How do mechanical and electronic scales work?

Mechanical, electromechanical and electronic scales

The first scales that carried the SECA logo were mechanical models. Scales are still found today in the range of products that evoke memories of the classic scales, which are of course much improved. In the course of further technical development, electromechanical scales came more into use. With these products, the weight is determined mechanically, but displayed digitally. Today, electronic scales ensure precise measurement results. Practical equipment and auxiliary functions round out weighing technology.

How does a mechanical scale work?

A mechanical flat scale works as follows. The weight acting upon the platform of the scale is transferred to a load lever system. The system reduces the weight acting upon the platform to the measuring equipment by a fixed transformation ratio. A weight that presses on the platform with 100 kg, for example, is reduced to 10 kg. In other words, the transformation ratio is 10:1. The load lever system is connected to the pointer by a pinion, so that the weight is displayed directly and without delay on the round dial scale.

With mechanical baby scales, free-moving weights are pushed onto a bar until balance is achieved and the result can be read.

How does an electronic scale work?

Electronic scales use various technologies to determine weight. SECA uses the patented tuning fork sensor technology amongst others. This technology ensures not only accurate results, but also reduces energy consumption compared to conventional digital measurement methods by a thousand fold. The result is easily read from the digital display. The energy source is most often a battery. There are also models with a mains plug. It is important that the scale has an energy-saving automatic shutoff. Some electronic scales can display more than weight. For example, they automatically calculate the BMI value if the body size is entered in advance.

This is how measuring technique works with tuning fork sensor technology

The pitch of a violin string depends on the force that is used to clamp it. Following this principle, SECA uses two opposing tuning forks connected at their ends on which a crystal has been soldered. Both crystals are operated in such a way by a suitable electronic circuit that the tuning forks continually swing. And with a pitch that depends on the force at which the ends of the sensors are pulled. The person being weighed causes the "pull".

How do I calculate my BMI?

The Body Mass Index, BMI for short, is the only value scientifically recognised worldwide for interpreting nutritional condition.

Definition:

BMI = body weight in kg / (body size in m)2

The interpretation of the BMI according to World Health Organization (WHO) criteria:

Underweight: < 18.5
Normal weight: 18.5 – 24.9
Overweight: 25 – 29.9
Obese: ≥ 30
Severely obese: ≥ 40

Copyright - SECA gmbh & co. kg

Weighing - a science in itself by SECA