What Is a Scale?
A Scale is a general term for a tool to measure the weight of a material.
Scales are used to measure relatively large objects (e.g., parcel delivery, food), while balances are used to measure relatively small and delicate objects (e.g., hospital or pharmacy medicine).
Scales and balances are classified as digital or analog, respectively. Digital Scales are available in a wide range of sizes and weights and are more widely used than their analog counterparts. On the other hand, analog scales are also in demand depending on the intended use, so it is necessary to distinguish between them.
Uses of Scales
Scales are used in different ways for digital and analog weighing.
1. Digital Weighing Instruments
Digital Scales are used for a wide range of applications, from minute measurements such as those of pharmaceutical preparations, to large scale calculations such as those used to calculate the weight of postal items. For example, highly accurate electronic balances are used to measure pharmaceutical preparations, and large scales that can weigh up to 50 kg are used to calculate the weight of postal items.
While electronic balances are highly accurate, they are easily affected by the operating environment and workers, such as air conditioning, humidity, and vibration. Therefore, it is necessary to review the environment and inspect the balance itself before weighing. Regular maintenance by a vendor is also important.
2. Analog Type Weighers
Analog Scales do not require high precision and are useful for speedy operations. Of course, like digital scales, they can measure relatively small to large objects. However, the advantages of analog scales are that they are less expensive and easier to maintain than digital scales, and they do not require a power supply or batteries.
Principle of Scales
Analog Scales, also called spring scales, are available in hanging, upper pan, and stand types. Scales use the elastic force of a spring to measure weight. On the other hand, an analog scale weighs an object on one side of the balance and a weight on the other.
The principle of a digital scale, such as a kitchen scale, is based on the load cell method. The weight is scaled based on the electrical resistance of the object to be measured when it is placed on the balance.
Digital balances are generally classified into two types: electromagnetic and load cell.
In the electromagnetic method, electromagnetic force is applied instead of weights used in analog balances, and the magnitude of the electric current is used to Scale the weight. Electromagnetic weighing is said to be more accurate than load weighing.
How to Select a Scale
When selecting a scale, pay attention to the following points:
1. Weight Capacity
All Scales have a maximum weight that can be handled. Therefore, in principle, the weight of the object to be measured should be less than or equal to the maximum weight that the scale can handle. If the weight exceeds the maximum weight, the scale will not be able to accurately measure the weight, and the scale itself may be damaged.
To avoid damage, it is important to select a scale that has some margin for the weight of the measured object. In addition, when selecting a specific weighing instrument, it is necessary to focus not only on the maximum measurement volume but also on the scale interval on display.
2. Scale Interval
The scale interval is the minimum value that a scale can measure. It is important to select the appropriate scale after confirming the necessary scale interval in advance.
For example, a scale that can measure down to 1 µg, such as an electronic balance, should not be used to measure postal items. If you try to detect too small a scale interval, the stability of the value will be slow.
3. Loading Surface Dimension
The loading surface dimension is the size of the pan on which the item to be measured is placed. It is important to select a measuring instrument with a dish that is large enough to accommodate the size of the object to be measured.
For example, if you are measuring powder or liquid in a container, you need to select a dish that is larger than the size of the container. This is because accurate weighing is not possible if the load is larger than the dish size.