Two years ago the version MFP 1000 HEPA for the determination of the fractional efficiency of HEPA filter media according to EN 1822-3 in the size range of 120 nm to 40 μm with the aerosol spectrometer system welas® digital has been presented and successfully introduced into the international market. With the development of the U-SMPS system (measuring particles in the size range of 5 nm up to 1 μm), a new high-performance measuring system is now available, integrated into the MFP.
The new MFP Nano plus with the integrated U-SMPS can test filter media with salt aerosols as well as with oil droplets, e.g. DEHS. By choosing the adequate solution concentration in the aerosol generator the mean generated particle size is precisely defined. Thus, the system can be matched to an optimum counting statistic for the particular MPPS range (Most Penetrating Particle Size). The polydisperse test aerosol is classified with the DEMC (Differential Electrical Mobility Classifier), so that only monodisperse particles of a particular size can get on the filter media for the determination of the efficiency. This procedure minimizes loading effects caused by
the test aerosol on the filter medium at the downstream measurement.
The new Palas® condensation particle counter UF-CPC 50 then determines fast and reliably the appropriate particle number concentration to each particle size. The UF-CPC 50 uses a large optical measurement volume and is therefore optimized for highest counting rates in very low aerosol concentrations.The very high particle concentration in upstream is reduced for the measurement by welldefined dilution systems. The integrated dilution cascades enable dilution factors of 10, 100, 1000 and 10000. For the simple switching between upstream and downstream measurement an automatic upstream/downstream switch is provided.
The cleaning effort at the dilution cascades is minimized by using two simple moveable dilution cascades, one for salt aerosols and one for DEHS. This leads to a fast, economic and defined determination of the filter efficiency according to EN 1822-3.
The series MFP for the evaluation of the dust holding capacity, the pressure loss and the efficiency of filter media has been proven to the entire satisfaction of our customers for years. The entire spectrum in air filter media testing, starting at very low efficient open media up to ULPA qualities, can be carried out with the different versions of the MFP series.