There are many applications that require a combination of high precision and legal-for-trade standards. Depending on the country, lab balances may need to meet requirements, such as EC or NTEP approval, or a certain class (like Class II), when used in certain applications. In this post, we'll take a look at standard features balances should have to be used effectively in industries such as pharmaceuticals and fields affiliated with biochemistry.
What does it mean when a weighing scale or balance is 'trade appoved'?
Trade approvals are usually issued by organizations that govern metrology in various countries. As such, certain types of approval are only valid in specific countries. For example, EC-Type approval is legally required for commercial usage in Europe, but holds no weight in the United States (where NTEP approval is needed). When a balance is certified by the required body, it means that it meets specific standards for accuracy, repeatability, reliability and other factors. You can read more about trade approval here. It is recommended that you familiarize yourself with the rules of metrology your balance must conform to wherever you operate.
What 'Class' refer to?
The weight class simply refers to the accuracy and division of the scale or balance to determine its usage dependent on equipment type or application. For example, a class II balance must display results from 1mg to 50mg (0.05g), and have a total of 100 – 100,000 divisions. The link above also has a table with classes and their increments. These balances usually have a lower capacity, which makes them right for biopharmaceuticals because the quantities weighed tend to be small.
Scale and balance GLP/ISO Compliance
Where approval and class are usually legally required for use in trade applications, GLP and ISO are guidelines that weighing instruments must follow in certain industries, particularly in labs. They help ensure the quality of the results by setting up rigorous procedures that must be followed in order to ensure quality and traceability. GLP-compliant balances make it easier to record a variety of variables, either by simply providing the information in the first place, or by making it easier to capture that information in printouts or software. It's also used for traceability, for example to manage inventory or dosage.
Features to look for in a pharmaceutical balance
Balances usually offer numerous features, and it can be difficult selecting relevant features amid all the many characteristics offered. If you are searching for a balance to be used in a bio-pharmaceutical laboratory, here are some points to consider:
- Purchase a balance that has the correct trade approval and class for their applications.
- Invest in a balance for the long-term. Poor quality could lead to loss of product, money and inaccurate results.
- Determine the capacity you will need, which depends on the amount you will be weighing.
- RS-232/USB interfaces allow balances to communicate with computers and printers, enabling easy transfer of raw data to software such as Adam DU for further study and recording.
- A stainless steel pan ensures quick, easy cleaning to avoid sample contamination.
- Some balances, like our, have a draft shield to ensure air currents don't interfere with small samples.
- Overload protection and capacity tracking reduce the chances of accidental overloads damaging the balance, and potentially increasing its longevity.
- Built-in applications such as parts counting, percentage weighing and totalization / accumulation offer users the ability to create bags and packages for products, improve inventory selection and make sample testing and formulation easier. While these features can be handy, keep in mind they're not approvable.
These aren't the only factors to consider when shopping for a lab balance, just some that can improve tasks frequently done in bio-pharmaceutical settings.
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