When selecting precision Digital Electronic Scales ther […]
When selecting precision Digital Electronic Scales there are, of course, tradeoffs that may be give-and-take between what you would like to have and what meets your particular needs. Since we’ve been on the subject of precision, accuracy and similar criteria let’s start with some refinements. Bear in mind that these are general distinctions and that you’ll want to discuss your specific needs with professionals such as the scientists at Tovatech.
Weighing capacity, generally indicated as the maximum weighing range, is as you would expect, the maximum load that can be placed on the precision digital scale weighing plate. The tradeoffs are in readout, reproducibility, and linearity. Scales with higher maximum load capability sacrifice readout, reproducibility, and readout. The significance may be small but should be taken into account based on your requirements.
Functionality covers what can be many weight-related functions that can be reported on the scale’s display. Many of today’s precision digital scales are quite versatile. In addition to displaying the weight of a sample other weighing-related functions they perform can include:
Piece counting. First, establish a reference quantity by placing a number of pieces (10 to 20 is generally recommended quantity and all must be the same) on the tared scale and enter the quantity. The scale calculates the weight per piece and enters it into memory. Top of Form
Piece counting functionality is extended when the scale is connected to a bulk scale and data transferred – a useful combination for inventory control. This greatly facilitates stock keeping. For more on this see our post on inventory management systems.
Check to weigh. Also termed tolerance weighing it allows users to set an acceptable plus or minus variation in weight and is achieved by programming the scale with lower and upper acceptable deviations from the target weight. This is because in many weighing applications what is important is the deviation of the target weight from a nominal value. How important is that deviation? For a box of cereal, a 1 or 2-ounce deviation may be acceptable to the buyer but to packagers of thousands of boxes, it is important. When compounding pharmaceuticals ± tolerances may be expressed in milligrams. Unacceptable deviations can be of major concern.
Recipe (batch) weighing. This feature is used when compounding products where strict control of ingredients is mandatory and when researchers create and vary formulations while seeking to develop new or improved products. Scales with recipe weighing capability range from milligram laboratory to kilogram production line models that can store multiple recipes in memory.
Percent determination determines the percentage deviation from the 100% target value.
Multiple weighing units. Scales with selectable weighing units allow users to select weighing units such as grams, kilograms, ounces, pounds, carats, and other units depending on particular models.
Hold or movement function. Also identified as animal weighing this is an important function when the load does not remain stable.
Veterinary scales are examples. As Fido wiggles on the weighing platform, the scale calculates a “stable” weight as an average value.
Record keeping capability. Recording results is a critical part of meeting GLP and GMP requirements. Precision digital scales equipped with a data interface such as a RS 232 or 485 allow users to connect the instrument to a printer or PC. Options depending on models offer USB, Bluetooth, and wireless LAN interface connectivity.
Other functions can include battery and rechargeable battery power and suspended weighing capability. Optional accessories can include dust shields, draft shields, density determination units, protective working covers, and secondary displays depending on the particular model of precision digital scale.