ATM 240/L

The aerosol generator ATM 240/L is used to generate a highly concentrated aerosol out of a suspension for testing air filters using polystyrene (PSL) particles. In sensitive areas such as semiconductor and aerospace industry the testing of high efficiency HEPA filters is often not carried out with the commonly used oily aerosol substances (DEHS, PAO, etc.).

Even the smallest amounts of these substances can be stored in the filter and outgas in the application and can lead to product damages. The standard DIN EN 1822-4 describes the filter test with solid particles.

Advantages

• Very high particle production rate (up to 1,5*10 11 per minute)
• High long-term stability of aerosol generation (VDI guideline 3491, part 2)
• Monodisperse particle size distribution with a low number of agglomerates
• Excellent scalability of particle production rate
• Leak test up to filter class U16 (filter format 610mm x 610mm, volume flow 600 m³ / h) within reasonable time

Applications

• Filter testing in sensitive areas such as the semiconductor and aerospace industries
• Filter test with non-outgassing aerosol substance and monodisperse aerosol
• Leak test up to filters of higher filter classes
• Production test during filter production
• Acceptance tests at the installation site of the filters

Principle

As a source for the filter test, the solid particles are referred to a particle size range called as MPPS (Most Penetrating Particle Size, in the range 0.1 … 0.3 microns).

A separation efficiency of a suspended matter filter determined with this particle size is always exceeded for other particle sizes.The PSL suspension is sprayed inside the device in a first process step by step via compressed air. Larger droplets get separated by the impactorand flow back to the suspension.This serves to avoid agglomerates. The water load resulting from the evaporation of the suspending agent is reduced byspraying at reduced temperatureto a minimum.

The smaller droplets are removed and dried in a second step by heated, dry and particle-free air.

The particles of the suspension contained in the droplets are transferred to the airborne state in this way and are available for a filter test as aerosol with solid particles. Due to the special design of the atomizer nozzle, a very high particle production rate is achieved. 

Specification