Posts Tagged ‘analytical balance’
Selecting Scale Weights for Calibration Testing
Calibrating precision digital scales, analytical balances and moisture analyzers that rely on accurate weight measurement requires periodic tests using a scale weight closely matching the maximum capacity of the instrument being tested.
Why Testing with Scale Weights is Important
Daily we depend on weighing accuracy – such as visits to the deli counter in the supermarket. We want assurance that the weight shown on the scale is accurate. The U.S. Government’s Weights and Measures Division sets the guidelines.
But in research labs and in food, drug and other production facilities, weighing accuracy assumes a highly critical criterion. This applies to weighing and measuring instruments where readout (the smallest weight difference displayed) and linearity (the ± deviation from the actual weight) are governed by GLP, ISO and other standards.
Adding to challenges, the accuracy of precision weighing and measuring instruments can be … Read the rest
How to Use an Analytical Balance: 5 Tips
University and industrial laboratory researchers requiring extremely accurate measurements of extremely small quantities rely on a precision instrument called an analytical balance. Shopping for an analytical balance requires being familiar with some of the advanced features available today as well as the proper use of these precision instruments. It is on the second point that we focus this post on how to use an analytical balance.
Here you will learn
- How to set up an analytical balance
- The effect of environment on weighing accuracy
- How samples can introduce errors
- The importance of personal practices
- Important maintenance tips
Inventory Management System Pairs Scale and Balance
An accurate inventory management system combining a reference balance and a bulk scale speeds the flow and accuracy of product quantities from the receiving dock through inventory control and outbound shipments. The high resolution Kern FKC stocktaking counting system, available from Tovatech, quickly calculates stock quantities, which can be transferred to a PC for record keeping. A barcode scanner can be integrated with the stock keeping system to reduce errors in stock identification.
The FKC inventory management system combines a KERN KB-N reference balances and a KERN FKA bulk scale.
Inventory Management System Components
1. Reference Quantities
Reference quantities are established with the Kern KB-N reference balance, available in maximum weighing ranges of 120 (KB 120-3N) or 1200 (KB 1200-2N) grams (4.23 or 42.33 ounces) and respective readout of 0.001 and 0.01 g, also representing the minimum piece weight. Individual piece weight is established by weighing a quantity of product … Read the rest
Tips for Analytical Balance Weighing Accuracy
Accuracy is a prime if not the prime criterion for analytical balances used in industries such as researching and compounding pharmaceuticals. Analytical balance weighing accuracy is a measure of how close the displayed weight is to the actual weight of samples on the weighing pan.
Two terms apply here. The first is readout, which is the smallest difference in weight that can be read and displayed by the unit. For an analytical balance it is typically 0.1 milligram or 0.001 g. Micro and ultra microbalances can weigh lighter samples.
Accuracy is sometimes confused with precision but it is an incorrect assumption. Precise means that results are consistent. However they may be consistently wrong, and therefore not accurate.
Instead, the second term or criterion to look for is linearity. Linearity is the maximum ± deviation of the displayed sample weight vs. the actual sample weight over the weighing range of the … Read the rest
Tips on Selecting a Laboratory Balance
A lot goes into selecting a laboratory balance. Let’s start with weight. You’ll need to select a balance that displays sample weight to the resolution desired. This is described as readout. Readout can be to several decimal places presented in grams or milligrams.
Select a balance with a weighing capacity in excess of the samples you plan to weigh. Some balances also specify the minimum load that can be placed on the weighing plate.
Why is this you ask? If the sample weight is not much larger than the expected weighing error, the measured value will be neither accurate nor repeatable. For this reason the spec sheet for laboratory balances may specify a minimum load. For the Kern ABT 0.1 mg readout balances available with maximum loads of 120, 220 and 320 grams the minimum load is 10 mg. But if you want to weigh samples less than 10 mg … Read the rest
Internal vs External Analytical Balance Calibration
Calibration is a procedure intimately associated with analytical balances. Calibration determines the relationship between the displayed value and true mass by comparison with a known mass. In other words, calibration determines the accuracy of an analytical balance or precision scale.
Suppliers of analytical balances and precision scales such as Tovatech have sources that provide calibration services and certificates for newly purchased equipment. Good laboratory practices, good manufacturing practices as well as conformance to several published regulations call for regular recalibration of these instruments and adjusting them if required. To accommodate this manufacturers such as Kern offer analytical balances and precision scales with automatic internal calibration and adjustment (if needed) or external calibration and manual adjustment.… Read the rest
How to Use a Precision Scale for Check Weighing
“Net weight one pound” it says on a bag of potato chips. You used to be able to buy a pound of coffee but now while the cans look the same the weights vary. One brand notes 11.5 ounces, another 10.3 ounces. Why is this? More than that, how do we know the can really contains 10.3 ounces of java? It is a conundrum we have to tolerate.
Joking aside, accuracy in weighing or in counting is no laughing matter when it comes to complying with rules governing net content and average weights. It is also important from a cost management perspective. While variances in potato chip and coffee weight is not a serious safety concern, putting more in the bag or can than called for is a cost management issue. Accuracy is a safety issue when it comes to pharmaceutical dosages and similar critical applications. Here is how precision … Read the rest
3 Good Questions About Precision Scales & Analytical Balances
Digital scales and balances are precision instruments. People using these instruments should be able to answer these questions:
1. How secure is your weighing data?
2. How accurate are your scales?
3. What is the degree of protection from dust and moisture?
How secure is your weighing data?
An answer can be found in Kern’s 32 bit software for Windows 95/98/NT/XP. It communicates between balances and programs such as Excel, Word, Access and others via a serial interface. Weight increments are inserted by the touch of a key or on a time-controlled basis to the current cursor location. This eliminates typing errors that may occur during manual inputting of weight increments.
Graphical displays of values and data … Read the rest