How to Eliminate the Greatest Enemy of Precision Weighing

The performance of micro analytical balances can be worsened by even the slightest of disturbances, and among others, static electricity is known to be especially troubling for many users. The BM series from A&D provides various means to help you perform such sensitive measurements with simplicity and accuracy, including a built-in fanless ionizer for quick and easy removal of static electricity. How to Eliminate the Greatest Enemy of Precision Weighing.

Problems due to static electricity

An electrostatically charged object induces the opposite charge in nearby objects. The resulting attraction will make stable measurement extremely difficult.

Error when weighing a charged object

The object will appear heavier. The value then changes as static is dissipated into the air or via the weighing pan.

Error when a charged object approaches

Static attraction can pull the weighing pan in the opposite direction and cause values to drift.

Filter papers, disposable weigh boats, and plastic centrifuge containers can all become charged just from normal handling. Charged powders can be displaced, causing cross-contamination.

Built-in fanless ionizer ◆

Simply hold the sample in front of the ionizer for a second or two to make sure that it is free of static before starting measurement.

Direct-current (DC) method

The ionizer of the BM series doesn’t use a fan to deliver ions and thus causes no breeze, which allows for neutralization of even extremely fine powders without disturbance.

Long life and high maintainability

The discharge electrode pins of the ionizer can be used continuously for approx. 10,000 hours. Each pin also has a protector for safe cleaning or replacement.

Making the world of micrograms accessible to all users

The BM series includes four models that display weight values with a readability of 0.001 mg; namely, BM-5, BM-5D, BM-20 and BM-22. These models are ideally suited for weighing samples for componential (quantitative, elemental, etc.) analyses, environmental analyses, or other applications that similarly require extremely fine weight measurements.

BM-22 5.1 g/22 g × 0.001 mg/0.01 mg (σ = 0.004 mg*1)

The BM-22 is a smart range model.*2 While being slightly lower in stability and repeatability (and therefore more affordable) than the BM-20, it still provides sufficient room for tare.

*1 Repeatability specification for 1 g weight
*2 The readability will switch to 0.01 mg automatically when the display value exceeds 2.1 g (BM-5D) or 5.1 g (BM-22) but returns to 0.001 mg by pressing the RE-ZERO key.

Ensuring accuracy and precision

Motor-driven internal calibration weight

All the models in the BM series are equipped with an internal calibration weight, which allows for any user to make certain that the balance always stays accurate and precise without any hassles.

One touch calibration

You can perform calibration (sensitivity adjustment) quickly and correctly any time with just one key press. For the 0.001 mg readability models, it can also be useful for a simple check of the environmental conditions at the time.*1

Automatic self calibration

The balance can be set to start calibration automatically when it detects a change in ambient temperature to prevent errors due to sensitivity drift.

Calibration test report

For daily accuracy checks and documentation, the balance is capable of testing for errors (without making any sensitivity adjustment) using its internal calibration weight, and outputting the result.

Internal weight value correction

In cases such as where the internal weight value varied over time, it can be corrected using an external weight that you have as a reference.

Automatic repeatability test

It is possible to have the balance measure the mass of its internal calibration weight 10 times and calculate the standard deviation to show repeatability under the given environment. This can also be easily included in your balance management SOPs for daily precision check.

Automatic response characteristics adjustment

The BM series automatically selects and sets the optimal combination of weighing speed and stability*2 (FAST, MID or SLOW) by analyzing the influence of external disturbances such as drafts and vibrations on the stability of the display value at the location. Alternatively, the setting can be configured manually.

*1 If internal calibration takes longer than usual, it is a sign that there is something wrong with the measurement environment, and it would be best to delay the measurement until a later time.

*2 The weighing speed and stability are in a trade-off relationship. The slower the weighing speed, the more stable the display becomes.

Managing data and compliance

User access control (UAC) and key lock to prevent misusage

The balance can be password-protected in two ways: The first way is to limit use to authorized individuals (up to 11 including one administrator—the administrator can perform all operations while other users are limited to measurements and calibration only) by setting a password for each user. The second way is to set a password just for the administrator and anyone else can use the balance without entering a password but for measurements and calibration only.

Moreover, upon receiving a command to disable its keys, the balance becomes operable only by sending commands from an external device such as a PC.

GLP/GMP/GCP/ISO compliant output

For documentation requirements, the balance manufacturer, model, serial number, ID number  (eight alphanumeric characters set by the user), date + time, space for signature for calibration report, calibration test report, and title & end blocks for a series of weighing results can be output.

Data memory

The BM series can store up to 200 weighing results (or 100 with timestamp) or the 50 latest calibration/calibration test results without requiring external memory devices such as a PC. The stored data can be output to a printer or PC in one batch.

Quick USB and RS-232C as standard interfaces

Quick USB enables readily sending data to Microsoft Excel, Word, Notepad, etc., in the same manner as keyboard input, requiring no driver software installation.*7 RS-232C allows for bi-directional serial communication (i.e. sending data and receiving commands) with a PC,*8 printer or other peripheral device. Via these interfaces, two different devices (e.g. PC and remote controller) can be connected simultaneously.

Further, an Ethernet interface (BM-08) is available as an option and can be installed in place of quick USB.

Providing simple but practical solutions for usability

Reverse backlit LCD display

The contrast of the black and white display provides excellent visibility even in dim light and prevents eye fatigue.

Interlockable sliding doors

It is possible to slide a door open using the handle on the opposite side. Effective use of both hands lets you perform weighing more efficiently.

Standard & highly recommended accessories

The BM series comes standard with various accessories that facilitate your workflows. There are also optional accessories that greatly help improve the stability of microgram weighing and are
therefore suggested especially for the BM-5/5D/20/22.

Catalogue: BM Series ENG