DGI-1570 (Dekati® Gravimetric Impactor) is a high sample flow rate cascade impactor designed for measuring gravimetric particle size distribution of particles < 2.5 µm. In a standard DGI setup particles are size classified into 5 size fractions with impactor stage cutpoints of 2.5, 1.0, 0.5 and 0.2 µm. If detailed information on the size distribution is not needed, some of the impactor stages can be removed from the DGI assembly. The impactor can e.g. be used without the 0.5 and 0.2 to stages to determine only PM2.5 and PM1.0 concentrations. The nominal sample flow rate though the DGI is 70 lpm which enables high sample yield even during short measurement periods. Typical measurement applications of the DGI impactor include engine emission measurements, air quality studies and other applications where high sample flow rate is needed.


DGI features

  • Particle size distribution in five size fractions <2.5 µm
  • High sample flow rate; each unit calibrated for 50, 60, 70, 80, 90 and 100 lpm
  • Easy-to-use stainless steel construction
  • Complete measurement solutions available from Dekati Ltd.

DGI is a cascade impactor that can be used to determine particle size distribution in any application where particles exist in its operational size range (<2.5 µm) and high amount of sample is available (sample flow rate 50 – 100 lpm). The DGI is commonly used in engine exhaust measurements since the high sample flow rate of the DGI enables high sample yield even in short measurement periods. Another typical application for the DGI impactor is air quality measurements, both indoor and outdoor air quality, where the sample particle concentrations are low and high sample flow rate is needed to collect enough particle material on the substrates for analysis. 

Inlet ISO ½” female
Outlet ISO ½” female
Collection substrates                                               47 mm, Aluminium foils
Back up filter 70 mm,Teflon coated fiberglass
Weight 1.5 kg
Dimensions 110 mm x 100 mm
Nominal flow rate                                                          70 lpm, calibration values provided for 50, 60, 70, 80 and 100 lpm

Stage D50 Cutpoints*

Sample Flow rate 50 60 70 80 90 100
Stage 4 3.0 2.7 2.5 2.3 2.2 2.1
Stage 3 1.2 1.1 1.0 0.9 0.9 0.8
Stage 2 0.61 0.55 0.50 0.46 0.43 0.40
Stage 1 0.26 0.23 0.20 0.18 0.15 0.13


*Each DGI impactor is individually calibrated before delivery for exact D50% values with the specified flowrates.

DGI is a 5-stage cascade impactor used to determine gravimetric particle size distribution of particles smaller than 2.5 µm. An impactor has two co-linear plates; one acts as a collection surface for the particles, the other one has small nozzle or nozzles in it to control the flow velocity. The sample flow is first led through the nozzles to achieve a certain, exact flow velocity. After the sample passes through the nozzles it is turned sharply in front of the collection plate in which case particles larger than certain size cannot follow the flow stream lines but are impacted onto the collection plate. Particles smaller that the stage cut diameter continue to the following impactor stages where they are further size classified and collected. By changing the dimensions in each impactor stage, different sized particles can be collected on different impactor stages. In the DGI impactor the impactor stage cut points are 2.5, 1.0, 0.5 and 0.2 µm at 70 lpm sample flow rate.



Before the measurement a collection substrate is placed on each of the impactor stages and this substrate is weighed before and after the measurement to determine particle mass size distribution. Depending on the used substrate material, a chemical composition of the collected particles may also be determined after the sample collection. In the DGI impactor particles >0.2 µm are collected on Ø47 mm substrates, particles <0.2 µm are collected on a Ø70 mm back up filter. Different material substrates can be used on the impactor stages depending on the requirements of the particle analysis method. In the DGI impactor, the collection substrates are held in their place by the jet plates of the stage so no additional lock rings are needed.

The flow rate through the DGI impactor is controlled with an external mass flow controller, and it can be adjusted between 50 and 100 lpm.  The nominal flow rate of 70 lpm gives the impactor stages cut points of 2.5, 1.0, 0.5 and 0.2 µm. The cut point values are calibrated and provided for 50, 60, 70, 80, 90 and 100 lpm flow rates.




Collection substrates
Different types of collection substrates can be used on the DGI impactor collection plates. The collection plates used in the DGI are designed for 47 mm substrates and Dekati offers aluminium substrates for this purpose. The filters used in the back up filter stage (< 0.2 µm particles) are 70 mm in diameter, and Dekati can offer TX40 fiber filters for this. For the suitability of different types of substrates and filters, please contact support@dekati.fi.
Other DGI accessories include:
Vacuum pumps  
DP25 230V/50Hz EUR IA-904
DP25 100V/50Hz JPN IA-905
DP25 115V/60Hz USA IA-906
Mass flow controller IA-100


DGI brochure

Available in customer pages section:

DGI Manual
Data processing spread sheet
Spare part catalogue

Can’t find what you’re looking for?
Contact Dekati technical support:       support (at) dekati.fi
Contact Dekati sales:                         sales (at) dekati.fi




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Related products:
DekatiĀ® PM10 Impactor