What is a powder weighing cabinet?
A powder weighing cabinet or balance enclosure is a cabinet type that protects the operator against the powder products that are being manipulated inside the cabinet. Often the application is weighing. The ventilator pulls the air from the cabinet and directs it trough a HEPA H14 filter that captures the particles.
What is the difference between a powder weighing cabinet and a ducted fume hood?
A powder weighing cabinet sends the air back into the lab after filtering it. A ducted fume hood sends the air outside using an HVAC system. When manipulating powders, the ducted fume hood comes with 2 problems:
- It is connected to the outside, so the variable flow rate of the wind will influence the flow rate of the air in the cabinet. This means pressure fluctuations that can influence the results of the weighing.
- Powders are heavier than air. In the turns of the HVAC system, powders tend to stay behind due to the centrifugal force.
Can I also weigh liquid chemicals within a powder weighing cabinet?
HEPA H14 filters are particle filters. Particles can be dust or microdroplets. Most liquid chemicals have evaporation of molecules that are not captured by the HEPA filters. Despite this, there is a solution. Carbon filters can be mounted on top of the HEPA filters. Carbon filters are filled with active charcoal that contains chemical coatings. These coatings can capture molecules by using a process called adsorption.