MODEL 1371


Electrical Mobility and Optical Particle Counting & Sizing

The compact Mini Wide-Range Aerosol Spectrometer (MiniWRAS) is the only portable instrument on the market that allows simultaneous and precise real-time monitoring of both micron-sized and nano particles.

Designed and specifically built for indoor air quality monitoring, the MiniWRAS is a fit for purpose, state-of-the-art system that combines optical and electrical particle detection in one single device.

This system offers many features, such as a 10 nm to 35 µm ultra-wide particle size range, simultaneous PM1, PM2.5, and PM10 measurement, 41 high resolution particle size channels, remote data transmission and instrument control. Easy to use, transport and deploy, it can be flexibly applied in various IAQ monitoring projects.

The MiniWRAS is the optimal solution for monitoring indoor PM values taking the nanoparticles into account and revealing the particle size distribution in the small nanometer range. It´s a perfect tool for indoor air quality monitoring at working places, inside vehicles, airplane cabins, trains, R&D testing, and many more.


  • ultra-wide size range from 10 nm to 35 μm
  • PM10, PM2.5, PM1 and particle size distribution, particle surface, and dust mass
  • high precision over 41 equidistant channels
  • no consumables
  • non-radioactive particle charger
  • versatile data aquisition and communication interfaces (Bluetooth, USB, RS-232)
  • easy to use with GRIMM software
  • optional sensor for temperature and relative humidity
  • self-test of all optical and pneumatic components for high quality standards
  • rinsing air for protecting laser and detector in optical cell


  • nanoparticle and PM monitoring (e. g. PM2.5)
  • Indoor Air Quality (IAQ) in buildings
  • IAQ in vehicles, airplane cabins, cockpits, busses, trains
  • nanoparticle source identification
  • workplace monitoring
  • R&D testing in industry

Technical Data

measured parameters

dust fractions acc. to EN 481 (inhalable, thoracic, respirable) PM10, PM2.5, PM1,
number concentration and size distribution

dust mass

0 – 100 000 μg/m3

particle size range

10 nm – 35 μm (10 – 193 nm electrical, 0.253 – 35 μm optical)

size channels

41 (10 electrical and 31 optical)

particle number

3 000 – 500 000 p/cm³ (electrical)
0 – 3 000 000 p/L (optical)


>97% of total measuring range (optical)

detection principle optical

light scattering at single particles;
detection volume aerodynamically focused, no border zone error

optical cell diode laser 660 nm


fast signal processing with 2 μs pulse length, 2 x 16 raw data channels

time resolution

6 s, 31 channels (storage interval 1 min)

detection principle electrical

electrical mobility spectrometer with Faraday Cup Electrometer

detector sensitivity

0.25 fA

time resolution 60 s, 10 channels 6 s each (storage interval 1 min)
volume flow1.2 L/min, ± 3% constant due to self-regulation
internal rinsing air flow rate 0.4 L/min, protects laser optics, reference air for self-test


GRIMM MiniWRAS software (wireless or data cable)


Bluetooth, USB, RS-232

analog input

external sensor for temperature and relative humidity

power supply

in: 100 – 240 VAC, 47 – 63 Hz, out: 18 VDC, 2.5 A

battery Li-lon battery, 14.4 VDC, 4.8 Ah for 8 h operation

dimensions (h x w x d)

34 x 31 x 12 cm (13.4 x 12.2 x 4.7 in)


7.6 kg (16.8 lbs)

operating conditions

+4 to +40°C (39 - 104°F), RH < 95%, non-condensing



Radial-symmetrical sampling head


Carrying case with foam inserts for 1371


Isokinetic sampling probe for flow rates from 2 to 25 m/s


external sensor for temperature and relative humidity

1159-10, 1159-100

capillary diluter (1:10 or 1:100)


GRIMM developed a powerful software to visualize, process, and import as well as export your valuable measurement data.
This easy-to-use program is compatible to Windows XP and all later versions.

Please contact us for your for free trial version if you already own a GRIMM measurement device or more information if you are in the process of finding your measurement solution.


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