There are many things that can influence the weighing accuracy of a balance. One aspect that can be overlooked are environmental influences. These typically include: temperature, humidity, air-flow, electrostatic charges and vibrations. Here we will outline how these factors may influence readings and possible solutions to overcome these.
Fluctuating temperatures can influence the accuracy of measurements, specifically when it comes to high-precision measurements. It can affect materials such as metal, and change the density of materials. The warmer the environment is, the higher the likelihood for expansion of materials. The cooler the environment is, the higher the likelihood for contraction of materials. Ambient temperature is best. However, the balance should be readjusted and recalibrated when the temperature shifts from ambient conditions.
Humidity will have similar effects to changing temperatures. The higher the humidity, the denser the air is. This can influence the readings taken from a balance. If the humidity changes, the balance should be readjusted and recalibrated.
Drafts and air movement create an instable environment, which can be caused by many things. These include:
- Other equipment (such as refrigerators and muffle furnaces)
- Poor room insulation
The best option is to keep the balance away from any potential air disruption. If air movement is unavoidable, there are options such as a draft shield that is available with certain balances.
A static charge can place an additional force onto the balance and certain materials from attraction and repelling. This will impact the results, mostly when it comes to high-precision balances. Factors such as the type of container a sample is stored in, humidity, and other devices can cause a static charge build-up. Store samples in glass containers instead of plastic to reduce this.
Vibrations are one of the most common environmental reasons for inaccurate results. A stable, solid surface is where the balance should be placed. Weighing should not be done near other equipment that may cause vibrations to the surface, such as shakers and centrifuges. An anti-vibration table can help cancel out environmental sources of vibrations to make readings more reliable. To find out more about anti-vibration tables, click here.
All blog information was provided courtesy of Ohaus.
Find our range of Ohaus balances and weighing equipment here.