Microbalances provide unparalleled accuracy in the microgram range. They offer readability out to 6-places, or 0.000001g (0.001mg). This level of accuracy requires a high-performance instrument with quality components and intricate design. However, a microbalance isn't able to perform to specifications without some special considerations.

Where You Use a Microbalance Matters

Microbalances require a controlled environment to ensure proper performance. Temperature fluctuations, drafts, humidity and vibrations will prevent them from measuring accurately. Drifting is a common issue with microbalances when environmental factors come into play. 

The most important considerations to make about the environment you are using a microbalance in are as follows:

Air Movement

Do not use a microbalance near any ventilation or high-traffic areas. People simply walking past the balance creates enough air movement to cause drifting. A heating or AC vent will cause issues if not properly diverted. It is highly recommended to use a microbalance as far away from any moving air as possible, as even the slightest draft can create enough of a disturbance.

Temperature

Microbalances should be used in an environment that isn't too hot or too cold. Manufacturer's typically provide a working temperature range for the instrument. The temperature should be consistently stable to prevent fluctuations, which can lead to reduced performance. 

Humidity

Be sure to follow the manufacturer's specifications in regards to humidity. Improper humidity can lead to static buildup which can also affect the performance of the microbalance.

Static

Humidity plays a roll in the presence of static electricity in an environment. Properly controlling humidity will help to reduce static build-up. You can take it a step further by isolating the microbalance from other electronics. If possible, use the microbalance in an area with hard flooring. Carpet can create static build-up as you walk across it.

Some microbalances, like Sartorius Cubis II microbalances, include a built-in ionizer that removes static from the weighing chamber. If your balance doesn't have that feature, external ionizers can be purchased separately.

Microbalances Hate Vibrations

One of the leading contributors to poor performance from a microbalance is vibration. Because they are so sensitive, they are influenced by vibrations at the location of the balance, or even from a distance. For example, we've seen microbalances used in facilities where hilos were present, and because the balance was in close enough proximity to that area, they were picking up the vibrations through the floor.

A proper work surface is imperative when using a microbalance. Anti-vibration tables are necessary, not optional, when using these instruments. They are built using a combination of materials like granite, isolation dampening components and steel frames to substantially reduce vibrations on the working surface. Whenever we quote a microbalance, we include a recommended an anti-vibration table to go with it. We've seen plenty of times where end-users place a microbalance on a standard workbench, and are unable to get accurate readings due to vibrational influence.

The video below is a quick demonstration of how well anti-vibration tables isolate a balance from vibrational interference. In this case, an A&D Weighing BM-20 microbalance is shown on both a regular workbench and a Scales Plus anti-vibration table. Tapping both tables shows how the balance responds. As you can see, the BM-20 on the anti-vibration table is virtually uneffected by the tapping.

How to Use a Microbalance for Best Results

Once you've setup your microbalance in an appropriate environment, you'll also want to be sure that you're operating the instrument properly to avoid any issues with performance.

Here are some tips on how to use a microbalance to get the best results:

• Use in a controlled environment (temperature and humidity control)
• Avoid use in areas where significant air movement is present (HVAC vents, high-traffic areas, etc.)
• Only use a microbalance on an anti-vibration table
• Ensure the balance is level before every use
• Let the balance warm up according to manufacturer’s instructions (often a couple hours or more)
• Perform an internal calibration if your balance has a built-in calibration feature
• For external calibration, use calibration weights that match the balance's class and sensitivity
• Always perform calibrations with the draft shield closed
• Use an anti-static device if needed to reduce static interference