The Dekati® ELPI®+ (Electrical Low Pressure Impactor) is a widely-used and well-characterized particle size spectrometer for real-time particle measurements. The ELPI®+ enables measurement of real-time particle size distribution and concentration in the size range of 6 nm – 10 μm at 10 Hz sampling rate. The measurement method of the ELPI®+ is the same for all the particle sizes, making the ELPI®+ the only instrument available in the market that operates in such a broad particle size range using only one measurement technique. Since the ELPI®+ also operates in a wide particle concentration range, it is well suited for both high and low concentration applications such as environmental air quality or direct combustion source measurements. The ELPI®+’s robust structure is designed to be used even in harsh environments and sample conditions, and the High Temperature version of the ELPI®+ can even be used to sample aerosols directly from 180 °C.

ELPI®+ measures particle concentration and size distribution in real-time at 10 Hz sampling rate. In the ELPI®+, particles are size classified into 14 size fractions in a cascade impactor. The size resolution of the ELPI®+ can be increased up to 500 size bins with the High Resolution ELPI®+ software upgrade where an inversion calculation based on the actual stage collection efficiencies is used. Since the particles are size classified in a cascade impactor, they can be collected and analysed for chemical composition after the real-time measurement. Additionally, ELPI®+ can be used for particle charge size distribution measurements, as well as for traditional gravimetric impactor measurements.

Please note that as from March 2024, the Dekati ELPI®+ will be replaced by the Dekati HR-ELPI®+ as the default model . The HR-ELPI®+ offers all current ELPI®+ standard features, with the additional benefit of having increased size resolution at your disposal. Please check the HR-ELPI®+ page for more information: High Resolution ELPI®+

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Features of the particle spectrometer

  • Wide particle size range 6 nm – 10 µm with one single instrument and one measurement method
  • Real-time (10 Hz) data on particle number, active surface and mass concentration and size distribution
  • Enables also measurement of particle charge size distribution
  • 14 particle size fractions, 500 with HR-ELPI®+ upgrade
  • Measurements from up to 180 ° C with the HT-ELPI®+ upgrade
  • Possibility to collect size classified particles for chemical analysis using analysis collection plates
  • Possibility for long-term maintenance free measurements with sintered collection plates
  • Wide operational concentration range
  • ISO16000-34 compliant measurement method for real-time determination of PM indoors
  • EN17199-1 and EN17199-4 compliant method for real-time dustiness measurements
  • ISO/TS 21361 compliant method to quantify air concentrations of carbon black and amorphous silica in the nanoparticle size range in a mixed dust manufacturing environment
  • ISO 17536 compliant method to determine separation efficiency of blow-by filters in internal combustion engines
  • Measurement method to determine ambient air number concentration and size distribution according to VDI guideline 3867 Blatt 6
  • Simple and robust construction with stainless steel impactor stages
  • Insensitivity to variations in sample pressure
  • Several data saving options including analogue inputs and outputs
  • ELPI®+ operation and features video in YouTube




Since the structure of the ELPI®+ is very robust, the operational size range of the instrument wide, and it operates in real-time, ELPI®+ is an ideal choice for various measurement applications. With Dekati® Sample Conditioning Instruments, Dekati can provide complete ELPI®+ measurement solutions for a very broad range of applications and even demanding measurement conditions. Typical applications for the ELPI®+ include:


Particle size spectrometer

Upgrade to advanced ELPI®+ versions

Most existing ELPI®+ units can easily be upgraded to High Resolution and High Temperature ELPI®+ versions without need for return to Dekati or local service center.

High Resolution ELPI®+
High Temperature ELPI®+