AVL Smoke Meter

The AVL Smoke Meter is a filter-type smoke meter for the measurement of the soot content in the exhaust of diesel and GDI engines.

AVL Approach

The AVL Smoke Meter uses the filter paper method to determine the Filter Smoke Number (FSN defined according to ISO 10054) and the soot concentration in mg/m³. The variable sampling volume and the thermal exhaust conditioning ensure an extremely high reproducibility and a wide range of application. The instrument can be used not only on large engines but also on light duty engines independent of their generation. In addition, raw exhaust measurements (e.g. upstream a DPF) or measurements up to 5000m altitude can be carried out by using device options.

Benefits at a Glance

  • High measurement resolution (0.001 FSN or 10 µg/m3) and low detection limit (0.002 FSN or 20 µg/m3)
  • Timely paper change due to remaining filter paper indicator
  • Altitude measurements up to 5000 m above sea level and altitude simulation up to 5000 m
  • High reproducibility, improved cleaning efficiency and increased robustness against wet exhaust gas due to shop air purging of the entire gas path – optional
  • Extended application area up to 3 bar exhaust back pressure for engines with exhaust aftertreatment systems - optional
  • Remote-control service with intuitive user interface – optional

Technical Data

Measurement principle Measurement of filter paper blackening
Measured value output

FSN (filter smoke number), mg/m³ (soot concentration)

Measurement range 0 to 10 FSN
Detection limit 0.002 FSN or 0.02 mg/m³
Resolution 0.001 FSN or 0.01 mg/m³
Exhaust pressure ranges (-300*) -100 to 400 mbar
(-500*) -200 to 750 mbar with the special sampling option
0 to 3000 mbar with the high-pressure option
(*) with activated altitude simulation
Maximum exhaust temperature 600 °C with standard 340 mm sample probe (800 °C with 780 mm long sample probe)
Interfaces 2 serial RS232 interfaces with AK protocol
Digital via Instrument Controller
1 Ethernet interface with InPort option installed with AK protocol
Power supply 100 – 115 VAC or 230 VAC, 50/60 Hz
Power consumption 700 VA (heated version)
Compressed air consumption (for shop air option) ~150 l/min during purge
Compressed air quality required Grades 1.1.1 to 1.4.1 according to ISO 8573.1:2001(E)
Recommended connection pressure on the AVL Smoke Meter: 5 to 8 bars at the measurement device input
Weight basic unit < 40 kg (without options)
Dimensions basic unit 560 x 620 x 300 mm (W x H x D)
Sample flow ~ 10 l/min
Ambient conditions

5 to 55 °C
max. 95 % relative humidity, without condensation


(as standard deviation)  σ ≤ ± (0.005 FSN + 3 % of the measured value @ 10 sec sampling time)


Measuring Principle

Filter paper method and variable sampling volume


A variable, but exactly defined sampling volume is sampled from the engine’s exhaust pipe and passed through clean filter paper inside the device. The filtered soot causes a blackening of the filter paper, which is measured by a photoelectric measuring head and the result is analyzed by a microprocessor. The determined values are the Filter Smoke Number (FSN defined according ISO 10054) and the soot concentration in mg/m³.


When determining the soot content, not only the paper blackening (PB) has to be taken into account,  also the volume of exhaust drawn through the filter paper is important (effective sampling length Leff).

FSN = PB for Leff = 405 mm (Length of the column of exhaust referred to 1 bar and 25 °C)