High Resolution ELPI®+


The Dekati® High Resolution ELPI®+ (HR-ELPI®+) is a completely new version of the widely used ELPI®+ instrument. The High Resolution ELPI®+ combines features of the ELPI®+ with data inversion algorithm that gives real-time particle number size distribution in up to 500 size classes 6 nm - 10 µm. This makes the High Resolution ELPI®+ a superior tool for detailed particle size distribution analysis in a broad size range that otherwise would need to be covered with two separate instruments. Other High Resolution ELPI®+ features include wide particle sample concentration range, robust structure and possibility to characterize chemical composition of the size classified particles after the real-time measurement.


High Resolution ELPI®+ features include

  • Wide particle size range 6 nm - 10 µm with one single instrument
  • Real-time particle number size distribution in up to 500 size classes
  • Possibility  to collect size classified particles for chemical analysis
  • Wide operational concentration range
  • Simple and robust construction
  • Insensitivity to variations in sample pressure
  • Several data saving options including analogue inputs and outputs

The wide measurement range of 6 nm  – 10 µm, superior size resolution and fast time response make the High Resolution ELPI®+  and ideal tool for a broad range of particle measurement applications. The low pressure impactor used in the High Resolution ELPI®+ is a robust, stainless steel detector that can be applied even to rough environments, and the use of impactor technology enables post-measurement chemical analyses of the size fractionated particle samples in the range of 16 nm – 10 µm. The High Resolution ELPI®+ can be combined together with Dekati® Sample Conditioning Instruments to take the sample from variable sample temperatures, pressures and humidities. High Resolution ELPI®+ applications include:

  • Combustion studies
  • Air quality measurements
  • Occupational health and safety studies
  • Automotive exhaust measurements
  • Blow-by gas measurements
  • Nanotechnology

ELPI®+ data in blue, HR-ELPI®+ data in red colour.                    Example High Resolution ELPI®+ data.


Particle size range                                      
0.006 – 10 µm               
Number of size classes 100 or 500
30 or 150 per decade
Sample flow rate 10 lpm
Sensitivity 250 #/cm3 for 10 nm particles
20 #/cm3 for 100 nm particles
1.0 #/cm3 for 1 µm particles
0.1 #/cm3 for 5 µm particles
HR-ELPI®+ dimensions H 407 x W 454 x D 242 mm
Collection plate diameter 25 mm
Unit weight 22 kg
Pump requirements* 20 m3/h at 40 mbar
Operating temperature 10 – 35 ºC
Operating humidity 0 – 90 % RH Non-condensing
Power 100-250 V, 50-60 Hz, 200 W
Sampling rate 1 Hz
Connection to PC (optional) RS-232 or Ethernet
6 analogue inputs 0 – 5 V
3 analogue outputs 0 – 10 V
Computer requirements MS-Windows 7™, 8™ or 10™  














*Suitable pumps available at Dekati Ltd.










High Resolution ELPI®+ operating principle is the same as ELPI®+ operation added with data inversion software. The particles are first charged into a known charge level in a corona charger after which they are size classified in a 14-stage impactor with electrically insulated impactor stages. Each impactor stage is connected to an electrometer that measures the current signal produced by the charged particle as they are collected on the impactor stage. The primary particle collection efficiencies and the amount of diffusion and image charge deposition have been determined for each impactor stage allowing determination of impactor Kernel functions.* The data inversion calculation method used in the HR-ELPI®+ is based on these Kernel functions and iterative calculation routine resulting in an accurate and reliable determination of particle size distribution with high size resolution. The inversion calculation runs in real-time and doesn't require any adjustments or optimizations from the user of the instrument.














* Järvinen, A., Aitomaa, M., Rostedt A., Keskinen, J. & Yli-Ojanperä, J. 2014. Calibration of the new electrical low pressure impactor (ELPI+). 2014. J. Aerosol Sci. 69, pp. 150-159.

Saari, S., Arffman, A, Harra, J., Rönkkö, T. & Keskinen, J. 2018. Performance evaluation of the HR-ELPI+ inversion. Aerosol Science and Technology, vol 52, pp. 1037-1047.

Spare Impactor + Charger Unit

Easily replaceable spare impactor and charger units are available as accessories for High Resolution ELPI®+. The spare impactor and charger unit can be used in the HR-ELPI®+ while the other impactor and charger unit is being serviced. This allows continuous HR-ELPI®+ measurements even during service breaks. Spare collection plate sets are also available as accessories.


Collection substrates

Different types of collection substrates can be used on the HR-ELPI®+ impactor collection plates. Even though gravimetric or chemical analyses are not made, collection substrates are recommended to be used to prevent fouling of the impactor. The collection plates are designed for 25 mm substrates and Dekati offers aluminium and polycarbonate substrates for this purpose. For the suitability of different types of substrates, please contact support@dekati.fi.


Dekati® Collection Substrate Spray

The collection substrates are often greased in impactor measurements to prevent particle bounce and blow-off from the impactor stages. The Dekati® Collection Substrate Spray is developed to grease the substrates faster and more evenly than with the traditional greasing methods. When used together with a stencil, the Dekati® Collection Substrate Spray enables an easy and fast way of applying a thin and smooth layer of grease on the collection substrates. The grease used in the spray is non-volatile also at low pressures and is therefore suitable for use in low pressure impactors, and also chemically pure enough to enable most chemical analysis to be done from the substrates. Stencils are available for 25 mm substrates that are used in the ELPI®+, High Resolution ELPI®+, High Temperature ELPI®+, ELPI®, DLPI+, DLPI and Dekati® PM10 impactors.


Dekati® Dryer

Since High Resolution ELPI®+ standard setup measures particles in real-time without any sample conditioning, it detects the particles as they are in ambient air and the measured particle size can be slightly different from the result measured with other methods that use a heated sampling line, dilution or particle dryer before the actual particle detection. This difference is caused by water absorbed by the particles which increases the particle size and mass especially in high humidity environments. The Dekati® Dryer DD-600 is a Nafion dryer used to remove water from the aerosol before it enters the ELPI®+ and it is specially designed for particle measurements and calibrated for particles. The Dekati® Dryer Setup DD-603 includes the Dekati® Dryer, PM10 inlet and all necessary connections for a complete setup in air quality measurements. In this setup, the drying air for the Dekati® Dryer can be supplied from the same vacuum pump that is used to operate the High Resolution ELPI®+ unit so no additional source for drying media is required.

Other accessories for High Resolution ELPI®+ include

Vacuum pumps  
DP25 230V/50 Hz, EUR IA-904
DP25 100V/50 Hz, JPN IA-905
DP25, 115V/60 Hz, USA IA-906
Sample conditioning and dilution  
Dekati® Cyclone for separtaion of >10 µm particles SAC-65
Sampling nozzles for isokinetic sampling SAC-100
Dekati® Diluter for aerosol dilution DI-1000
FPS-4000 for emission dilution FPS-4000
DEED Dekati® Engine Exhaust Diluter DEED-100
Dekati® Axial Diluter DAD-100

For more accessories, please contact Dekati Ltd.

High Resolution ELPI®+ brochure

Available in customer pages section:

ELPI®+ Manual
HR-ELPI®+VI Manual
Data processing spread sheet
Spare part catalogue


Maintenance videos available in Youtube.

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




To use a PDF document, a reader program must be installed on your computer to display, print, and navigate. The Adobe Acrobat reader is available for downloading at no cost from Adobe's Web site at http://www.adobe.com [http://www.adobe.com]. To ensure you will be able to see a PDF file in its entirety, please obtain the most recent edition of the free Acrobat Reader

Related products:
High Temperature ELPI®+