Compact Scales / Compact Balances

Compact scales are usually the scales to set-up, in which the weighing platform and the display and operating elements are arranged together in one housing. The compact scales can be equipped with mechanical, hydraulic or electronic elements for weight determination and analogue or digital display. In the following sections, however, we will focus specifically on the models with digital display and electronic weighing.

Important selection criteria for digital compact scales
Since there are many different areas in which compact scales can be used, the required features and functions for the individual applications sometimes differ considerably. First of all, it should be clarified whether verification is required for the intended use. If so, this considerably limits the number of available models and certain requirements must be observed when using them. Before comparing different models, it is helpful to determine the minimum requirements. The following criteria should be considered:

- Legal for trade
- Weighing range, resolution and accuracy
- Dimensions of the housing
- Shape and size of the weighing plate
- Draft shield
- Calculation and evaluation functions
- Storage options, interfaces
- Permissible operating temperature
- IP protection class
- Mains or battery operation

Weighing range, resolution and accuracy of compact scales
Since the weighing surface is limited and the compact scales are almost always used as bench scales, the permissible weighing range is rarely higher than 30 kilograms. Much more common are the models with a maximum load of only a few kilograms or a few hundred grams. The lower the maximum load is, the smaller the weighing surface of the compact scales. With the same maximum load, different series can differ considerably in readability and accuracy. For example, there is a model that displays a maximum load of 6,000 grams with divisions of one gram, while another compact scales with the same maximum load can already show weight differences of a tenth of a gram on the display. Unless otherwise stated, the accuracy is three to four times the readability. This means that the compact scales with a higher resolution usually also have a higher accuracy.

Differences in the design of the compact scales
Almost all models of the compact scales are built in such a way that they are primarily suitable for being set-up on a table or a raised shelf. The housing is relatively flat and can usually be aligned horizontally by means of two or four adjustable feet. The display and the operating elements are usually arranged on a more or less inclined surface in front of the weighing plate, so that the user can simultaneously see the display and the operating keys as well as the product to be weighed. The weighing plate can be rectangular, square or round and can almost always be removed for easier cleaning. Since the weighing surface should be loaded as centrally as possible, it is recommended to use the compact scales the weighing plate of which is not smaller than the weighing pieces or the weighing container.

Differences in functionality can often be seen in the external design. A numeric keypad for the function keys and a display divided into three separate areas are features that characterise the compact scales with extended piece counting functions. If, in addition to the main display, the scales have an additional display on the opposite side of the housing, it is particularly suitable for weighings, the process of which as well as the results are to be observed by several people. If such compact scales are also verified, it can also be used for trading purposes. A draft shield is an indication of the high-resolution scales where the weighing should not be distorted by air movements or fluctuations in humidity. If the compact scales are to be used with a draft shield, it is essential to ensure that its dimensions and opening options do not hinder the intended weighing procedures.

Additional functions of the digital compact scales
Digital scales can often do more than just display weight. The most common functions include zeroing the unloaded scales, selecting the weight unit and taring. The tare function means that the weight of the weighing containers or packaging is not included in the displayed result. Almost all the versions of the digital compact scales have a calibration function with which they can also be adjusted via the device menu by using suitable calibration weights. Many models also offer additional calculation and evaluation functions with which quantity checks can be considerably simplified and accelerated. These include, for example, limit weighing, percentage weighing and piece counting.

For applications where the weighing results are to be further processed on a computer, the models that can store or directly transmit the data are recommended. In most cases, RS232 or USB interfaces are offered, via which the data can be sent directly to the USB interface of a computer using a suitable interface cable. Special software facilitates the evaluation of the transmitted electronic data and the insertion into specific user programmes. If it is not possible or desired to connect the compact scales to a computer during weighing, there is the alternative option of transferring the results to a special memory element connected to the interface and reading this out later on the computer.

Compact scales for mobile or stationary use
Due to their design, the compact scales can usually be transported and used at different locations without any problems. Care must be taken with the very high-resolution models because they are particularly sensitive to environmental conditions. These scales should therefore be given a fixed place in the laboratory or workshop, which may only be changed for important reasons. If it is necessary for operational or other reasons to use the compact scales frequently in different places, it is advisable to choose a model that can be operated with batteries. In addition, if the scales are to be used in the areas where the climate does not correspond to the indoor climate of the common offices, it is important to check the temperatures for which the electronics of the compact scales is designed. If the environment at the place of use has a high dust and moisture content, the compact scales should have a high IP protection rating.