What is inertial impaction in filtration?
What is inertial impaction in filtration?
Inertial impaction occurs when a particle is so large that it is unable to quickly adjust to the abrupt changes in streamline direction near a filter fiber. The particle, due to its inertia, will continue along its original path and hit the filter fiber.
Which is better HEPA or ULPA?
ULPA filters trap more and smaller particulate matter than HEPA filters. ULPA filters are 99.999% effective at removing submicron particulate matter of 0.12-micron diameter or larger, while HEPA filters are 99.97% effective for eliminating particulate matter of 0.3-micron diameter or larger.
Where does inertial impaction occur?
Inertial impaction occurs when there is a sudden change in the direction of the flow, which causes particles to deviate from the air streamlines as the inertia of the particles keeps them on their initial trajectories.
What does ULPA stand for?
Ultra Low Particulate Air
The acronym ULPA stands for Ultra Low Particulate Air. (As a refresher, HEPA stands for High-Efficiency Particulate Air).
What is direct interception?
Direct Interception. This type of mechanism is characterized by a particle that follows a fluid streamline and does not deviate from that streamline. Usually, a particle will be captured if it comes within one particle radius of a fiber.
What is diffusional interception?
Diffusional Interception. Diffusional interception is only found in air filtration. It is the main reason very small particles, smaller than the filter media pore size or flow path, are retained (Figure 4). It occurs because air molecules are always in a state of random motion.
What is a ULPA filter made of?
borosilicate glass microfibers
Both HEPA and ULPA filters consist of innumerable tiny strands of randomly arranged borosilicate glass microfibers. Flowing through this vast labyrinth of fibers, particles get arrested through various physical mechanisms, the main three being interception, inertial impaction, and diffusion.
Where is ULPA filter used?
ULPA filters are often used in applications where airborne particles and pathogens are dangerous to human health or essential in manufacturing or assembly operations of sensitive equipment. They are also used in environments that require ultra-pure air to remove the risk of contamination.
What is inertial movement?
This is called inertial motion. Inertia means an object in motion to remain in motion, while an object at rest will remain at rest unless acted on by an external force. It’s a fundamental property of mass.
What is ULPA filter made of?
Both HEPA and ULPA filters consist of innumerable tiny strands of randomly arranged borosilicate glass microfibers. Flowing through this vast labyrinth of fibers, particles get arrested through various physical mechanisms, the main three being interception, inertial impaction, and diffusion.
What is clarification and filtration?
The difference between clarification and filtration is that clarification refers to the removal of smaller amounts of solid particles from liquids. In contrast, filtration refers to the clarification of a liquid that contains solid particles via filtering off the liquid through a filter.