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Balance Enclosure: For Measurement of Hazardous Materials
Naoto Izumo
R&D Division 5, A&D Company, Limited

 

Balance Enclosure: AD-1673 + Micro analytical balance: BM-20

Two years ago we released the micro analytical balances BM-20/22. With the continued sale of these analytical balances we here at A&D have come to two realizations. The first is regarding the necessary environment for stabilizing microbalance measurements. Secondly, we have also gained some knowledge about the samples measured by microbalances.

I would like to summarize this information we learnt from our experiences in the marketplace into a concrete proposal, which can act as a guideline for realizing better weighing practices.

The progression from testing theoretical knowledge regarding measurement environments with actual data in the fields to making a product that stimulates latent demand takes both a long time and a very determined effort. However, this product development process is an issue of significant importance for an equipment maker, essentially one they will have to stake their continued existence on. Using earlier market research and our many experiences from product development and sales, we have proposed the tools below for tangible improvements in measurement environments.

1) Suggestions for the measurement and elimination of static electricity in measurement samples

Electrostatic field meter: AD-1684 / Analytical balance with built-in static eliminator: BM Series / Static eliminator: AD-1683

2) 24-hour measurement and evaluation of measurement performance in real measurement environments

Conducting AND-MEET

3) Suggestion for the simultaneous recording of temperature, humidity, air pressure, vibration and weight values in order to properly evaluate a measurement environment

Weighing environment logger: AD-1687

4) Suggestions for anti-vibration table for weighing instruments and tabletop breeze break as tools for improvement of measurement environment

Tabletop breeze break: AD-1672 / Anti-vibration table (for reduction of minute vibrations): AD-1671

These tools are effective in locations where microgram weighing is performed, and have made it possible to achieve such ideal performance levels that the minimum sample weight is now below 10 mg at those locations. On the other hand, by proposing these tools to the market we were able to understand the measurement needs of microbalances at the location of use and this led to some understanding of why microbalances would be purchased in the first place.

For example, microbalances are used in locations where measurements of minute amounts are required, the samples to be weighed could be used for organic microanalyses of food additives and proteins, etc., or as samples used to analyze the tiny elements found in dirt or mud. They also have many uses in other fields, such as analyzing small patches of rust which develop on the surface of a metal, managing the thickness of the metal thin film that is coated onto the surface of solar power photovoltaic panels, evaluating the surface treatment of separators for use in lithium ion batteries, managing the amount of resist ink used in the small size panels typically found on smart phones, or even measurement of PM2.5* trapped in filters ? the tiny particulate matter that floats in the air and is now becoming regarded as a serious health concern ? as well as measuring amounts of equally small car emission particles (Euro5*).
　
Other than the examples above, recently microbalances have come to be used for the volume measurement and management of micropipettes, whose discharge volumes are as small as a few microliters.

Across these fields, BM-20/22 microbalances have a proven delivery record and have achieved a steady reputation in the market in a variety of different locations, including national and public research institutes such as the Advanced Industrial Science and Technology (AIST), universities, clinical testing laboratories, public environmental measurement institutes, leading automobile manufacturers and pipette makers, etc. Further, while this also relates to the fields mentioned above, the growing market needs in fields such as pharmaceuticals or biotech for measurement of hazardous materials have also been recognized.

Examples of the hazardous materials mentioned here could be highly potent compounds such as anticancer agents or medicines, dust caught in filters with traces of radioactivity, materials containing asbestos, nanoparticle material, or fine powders from hazardous metals such as beryllium or cadmium. In particular, anticancer agents, which are manufactured as powders and then dissolved into liquids for use, regularly require weight measurement at the point of production and along all stages of research, so there is a constant concern of exposure to toxic substances for all those performing such work.

In the measurement environments of those hazardous materials mentioned above, the use of glove boxes or fume hoods have already been introduced as safety measures. The glove box is a device for sealing off dangerous viruses, etc., but it has the problem of being extremely difficult to handle. The fume hood is used for the elimination of foul odors or hazardous gases from substances such as organic solvents. While it is possible to eliminate gases with a fume hood, it does create the problem of destabilizing the measurement values of the balance inside due to the air current caused by the strong suction power of the fume hood. Further, there are also problems with its capability of containing hazardous materials.

The balance enclosure, on the other hand, is a device designed for conducting weight measurement of hazardous materials while also managing the safe handling of those materials. It literally encloses a precision balance inside and allows weighing of materials like highly potent compounds while protecting the operator from exposure to such materials. A&D introduced our balance enclosure as a sample exhibit at JASIS (formally the JAIMA Expo) in September last year, which was the first balance enclosure proposed by a balance manufacturer in Japan.

For a demonstration of the containment abilities of the AD-1673 balance enclosure please refer to the video below.

 Demonstration of the containment abilities of the AD-1673

To boil down the necessary features required for a balance enclosure, the 4 requirements below could be considered the most essential:

(1) In order to prevent the dispersal of air-borne particles outside the unit, laminar airflow must be maintained above a certain level
(2) A powerful HEPA filter unit must be equipped to catch and collect all hazardous particles
(3) It must be possible to see clearly how much the device has been contaminated by hazardous particles
(4) It must be able to be maintained safely, simply and at low cost

The AD-1673 has been released as a product which satisfies all of these important demands.

Except for the underside of the AD-1673, all component parts of the unit are made from a transparent resin, meaning users can confirm if contamination has occurred at a single glance. An air flow monitor is fitted to ensure that a fixed air speed is maintained. In order that the HEPA filter can be replaced by the user themselves, the HEPA filter operates as a stand-alone unit and both devices are connected by a duct. With this set-up, when the user unfastens the duct from the enclosure, the air flow channel to the enclosure is blocked and it is possible for the user to replace the integrated small HEPA filter unit and duct system. The HEPA filter is covered so that it is isolated from its surroundings, which enables replacement using a simple bag-in-bag-out method, where the user does not need to touch the filter directly with their hands. Also, the balance enclosure itself is not a fixed, stationary-type device, but was designed as equipment that can be placed upon a desk, moved about or added to existing facilities.

Due to the necessity of environmental measurement, as well as the revitalization of markets related to new material development, sectors where microbalances are being used have been expanding, and this trend is expected to continue for some time. In response, A&D would like to offer the associated necessary equipment and contribute to market support by offering overall improvement to weighing environments.

*1 PM2.5: An air pollution index measuring particulate matter smaller than 2.5μm that enters the lungs and is hard to expel through the lungs' air sacs. The particulate matter can be a major factor in lung cancer and other illnesses. The resulting air pollution along major roads has long been viewed as a major problem

*2 Euro5: Regulations on automobile emissions within the European Union. The maximum particulate emission amount for automobiles in the EU is 5mg/km

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