Aerosol Spectrometer / Particle Counter / Photometer
VDI 3867
ISO 21501

FMS 375 - Fractional Efficiency Measurement System

The fractional efficiency measurement system FMS 375 bundles core competences of Topas in one compact and robust instrument for highly-resolved aerosol analyses regarding particle size and concentration.

The FMS 375 enables in one device i) an automated aerosol sampling as well as excess air refeeding via a switching unit, ii) aerosol conditioning by two dynamic dilution systems and iii) a precise aerosol characterisation based on the aerosol spectrometer LAP 325.

  • operable at both over and lower pressure
  • automated and remote-controlled operation
  • mobile use (optional trolley kit)
  • characterisation of particle size distributions of aerosols
  • evaluation of fractional separation efficiency of oil mist separators and filters
  • compact design for the use at engine test stations or in laboratory test setups (e.g. SPT 140)

By means of two flexible sampling lines, the FMS 375 is connected to the sampling points. The automated switching unit allows a controlled sampling via the different sampling lines. After sampling, the aerosol conditioning takes place. Two cascaded dynamic dilution systems enable a defined reduction of the concentration level over several orders of magnitudes. The present raw gas concentration defines the necessity for none, one or two dilution systems for lowering the concentration towards the acceptable concentration range for the aerosol spectrometer.

Afterwards, the conditioned aerosol passes the measuring cell of the aerosol spectrometer. The measurement zone is illuminated by light of two different wavelengths, which originates from two laser diodes with high lifetime. The light, which is scattered by the particles or droplets, is collected and recorded by a photodetector. The optical signals are converted into electrical ones and are processed by a microcontroller. Signal evaluation is performed by the firmware. Results like the particle size distribution and the particle number concentration are visualised on a display.

sample flow rate: 3 l/min
analytical flow rate: 0,1 l/min
size range: 0,2 … 40 µm
concentration range: < 4 x 108 cm-3
aerosol inlet: 8 mm (outer diameter)
temperature range: max. 120°C
pressure range (inlet): max. ± 800 mbar
power supply: 110 … 240 V, 50 … 60 Hz
compressed air supply: 4 bar £ p < 8 bar
data interface: ethernet, USB
dimensions (w × h × d)
w/o grip
with grip
530 × 440 × 500 mm
650 × 570 × 500 mm
weight (w/o accessories): 33 kg