Aerosol Spectrometer / Particle Counter / Photometer
ISO 21501

FAS 362 - Particle Counter for Liquids

The Liquid Particle Counter FAS 362 is designed for measuring particle size distribution (PSD) and particle number concentration of particles in liquids.

Determining the mean extinction (attenuation) of the light due to single particles is an efficient optical measuring method to measure the particle size in a wide range. This method of single particle measurement is applied in the liquid particle counter FAS 362.

By means of competetive solutions this instrument is capable of measuring particle sizes with a high resolution and good reduction of the systematic measuring deviation. The complete detection of all particles present in the measuring volume is ensured even at high measuring concentrations.
Detecting the extinction at a special angle to the measuring cell (sensor position) – according to ISO 21501-3 – reduces the influence of the particle material.

The comfortable software PASWin for controlling the instrument and analysing the measuring data enables easy use and flexible application.

  • Wide particle concentration range: max. 5000…20’000 particles/cm³)*
  • Wide dynamic range particle size range: (1) 2…200 µm*
  • Excellent size resolution: 64 size channels
  • User configurable measuring ranges and size channels
  • Extreme low dependency on particle material by the use of especially developed patented optics
  • Optimally designed sensing volume
  • User friendly Windows® software
  • Robust, small dimensions and low weight
  • Flexible sample glas vessel with stirrer

*depending on applied measuring cell


  • Control of a micro balance via serial interface for exact concentration determination
  • Pump control for continuous sampling by means of a external pump
  • Measurement of particle size distributions as well as concentrations
  • Cleanness / purity analysis
  • Determination of separation efficiencies
  • Flocculation investigations
  • Analysis of biological or bacterial systems
  • Device carrying case
  • PSL latex suspensions or narrow distributed, certified materials for calibration
  • Micro balance for determination of analysed volume or volume flow, respectively, with additional serial interface and integration in software PASWin
  • Peristaltic pump for continuous sampling or for slightly viscous liquids

For the series FAS, the physical effect is used that an illuminated particle causes a definite light extinction (blockage) corresponding to its cross section and size, like described in ISO 21501-3. For this, the particle system is continuously streaming through a sensing zone inside a measuring cell. Particle concentration and measuring volume must be in such a relation that with high probability, the sensing zone contains only one particle at any time. Electrical pulses of the photo detector caused by single particles are amplified and classified by their height into different channels.


Measuring principle Impulse height analysis with light extinction (single particle counting)
Particle size range 1.5 µm…100 µm 2 µm…200 µm
Measuring cuvette 0.3 mm x 0.6 mm 0.5 mm x 0.75 mm
Measuring volume 10 ml/min 30 ml/min
Max. measuring concentration 20·103 particle/cm3 5·103 particle/cm3
Light source Laser diode, 5 mW, l=670 nm
Photo detector Hybrid photo diode amplifier UDT-455HS
Interface RS232C / USB Adapter
Power supply 100 … 260VAC
Dimension signal processing unit 290 mm x 230 mm x 120 mm
Required space for sample feeding unit 320 mm x 300 mm x 650 mm
Weight of signal processing unit 2.1 kg
Weight of sensor, sample feeding unit, tripod 6.2 kg