MSSplus - AVL Micro Soot Sensor

The new AVL Micro Soot Sensor Generation MSSplus is a system for the continuous measurement of lowest soot concentrations in the exhaust gas from internal combustion engines.

AVL Approach

AVL Solution

The MSSplus is the only measurement system on the market that is able to measure the concentration of soot directly and without cross-sensitivity to other exhaust components. The MSSplus operates based on the photoacoustic measurement principle. Thanks to the measurement cell design and enhanced electronics of the MSSplus, a particularly low detection limit of 1 μg/m3 in combination with a reduced signal noise is achieved. However, the MSSplus has not only been refined for low emission measurements, but also for the measurement of raw exhaust gas with the integration of an automated thermophoretic loss compensation (TLC). The TLC function compensates the particle losses resulting from thermophoretic deposition at the sample point and enables an automatic calculation, display and logging of the loss corrected soot signal.

Benefits at a Glance

  • Transient measurement of soot concentration [mg/m3]
  • Sensitive to soot (not interference to other exhaust components)
  • High sensitivity (resolution 0.01 µg/m3, detection limit 1 µg/m3)
  • Wide measuring range (1-1000 mg/m3)
  • Measurements upstream and downstream of DPF (back pressures up to 2000 mbar, temperatures up to 1000°C)

Technical Data

Measuring range
Measured value concentration of soot (mg/m3µg/m3)
0.001 – 50 mg/m3
Turndown ratio
(min:max concentration)
Display resolution 0.01 mg/m3
Detection limit 1 µg/ m3
Data rate: digital / analog

up to 10Hz / 100 Hz

Rise time (t10-t90) < 1 sec
Operation temperature 5°C to 40°C
Sample flow 4 l/min
Interfaces TCP/IP, RS232 with AK protocol, digital I/O and analog I/O
Power supply 90...240 V AC, 50/60 Hz, 400 VA
Laser class Class 1 laser product
Unit dimensions
measuring unit
W x H x D
~ 19" x 5HU x 530mm
Unit weight measuring unit ~ 20 kg
Consists of conditioning unit, pressure reduction unit and dilution cell
Dilution ratio (DR)
The actual DR will be displayed with the accuracy noted below
Adjustable from 2 - 20
Accuracy (DR display) Max. +/- 2 + (DR*0.5)%
Pressurized air input 1 +/- 0.2 bar gauge pressure required
Flow Min. 4 l/min
Exhaust gas temperature Up to 1,000 °C
Exhaust gas back pressure Up to 2,000 mbar
(mean pressure)
Pressure pulsation +/- 1,000 mbar, but max. 50% of exhaust gas back pressure (mean pressure)
Blow by amount of the pressure reduction unit depending on pressure ~ 40 l/min at 1,000 mbar exhaust gas pressure and 25°C
Power supply 90…240 V AC, 50/60 Hz, 500 VA
Dimensions conditioning unit

W x H x D
~ 19" x 4HE x 530 mm

Weight conditioning unit

~15 kg


Measuring Principle

Photoacoustic measurement principle

The AVL Micro Soot Sensor is based on the photoacoustic measurement method. With this measurement method, the sample gas with "black", i.e. strongly absorbing soot particulates, is exposed to modulated light. The periodical warming and cooling and the resulting expansion and contraction of the carrier gas can be regarded as a sound wave and detected by means of microphones.