DMM, Dekati® Mass Monitor, is a real-time measurement instrument for monitoring PM emissions from diesel and gasoline vehicles. Used either with a tailpipe sample conditioning system or existing CVS tunnel the DMM provides second-by-second information about vehicle PM mass and number emission. In addition to particle mass concentration, DMM also provides information on particle number concentration and particle size distribution (MMD and GSD). Since the DMM is intended for daily routine usage special attention has been paid for usability issues. Ease of use, reliability and integration to test cell information and data logging systems have not compromised the accuracy and sensitivity of this system. DMM detection limit is as low as 1 µg/m3, time response 2-3 seconds and repeatability is better than with gravimetric measurement.

DMM features

  • Real-time particle mass and number concentration
  • Information on particle size distribution: MMD (Mass median diameter) and GSD (Geometric standard deviation)
  • Measures all particles (PM), not only black carbon
  • Outstanding sensitivity down to 1 µg/m3
  • Can be used in CVS and tailpipe measurements in both pre- and post-DPF conditions with a well-designed sample conditioning system, e.g. the DEED or FPS.
  • Robust and easy-to-use system

DMM is specifically designed for automotive PM emission measurements, and in this field it can be used for all development and routine measurement purposes. Common DMM applications include:

  • Engine development and ECU tuning
  • After treatment device development
  • Raw exhaust or CVS tunnel measurements
  • Steady state, transient and on-board testing

Engine development

The DMM can be used in all engine development applications, including basic combustion research, engine control software development, after treatment development and new engine type research (HCCI, GDI). Due to the fast time response the PM emissions are seen both in acceleration and steady state conditions, as well as in cold and hot start measurements. Together with Dekati® Sample Conditioning Systems, the DMM can be connected directly to engine tailpipe in both pre- and post-DPF conditions, or a CVS tunnel.

Example data on real-time PM emission: ”Red car” is emitting a lot of particles during accelerations


After-treatment device development

Due to the wide dynamic range of the DMM it can be used for particle measurements both upstream and downstream of any after-treatment device (oxidation catalysts, particle filters, open filters, SCR catalysts and so on). The sensitivity of the DMM goes down to 1 µg/m3 enabling accurate measurements even in post-DPF conditions. With a well designed sample conditioning system (e.g. Dekati® FPS or Dekati® DEED) the DMM can be connected directly to the tailpipe and the PM removal efficiency can be seen immediately in particle mass and number concentrations as well as particle size.


On-board applications

DMM’s robust structure makes it ideal also for PEMS measurements i.e. on board vehicle measurements.DMM’s relatively low power consumption (200 W) allows easy installations to moving vehicles. an additional approximately 500 Watts more is needed for the vacuum pump. A dilution system suitable for these measurements is e.g. a combination of a Dekati® Diluter DI-1000 and Dekati® Axial diluter DAD.

Particle size range 0 – 1.2 µm
Number of stages 6 impactor stages + one mobility channel
Flow rate 10 lpm
Lowest stage pressure 100 mbars absolute pressure
Operation temperature                                                      
5-40 ºC
Operation humidity 0-90 % R.H.
Sampling frequency 1 Hz
Concentration range From 1 to 1000 µg/m3 (up to 5000 µg/m3 for short periods of time), or 100 - 10E+06 #/cm3
DMM unit dimensions Installable to 19” rack, 6 U height:
W x H x L 450 x 266 x 400 mm
Unit weight
40 kg
G 3/8” thread, 10 mm male pipe connector
G 3/8” thread, NW-16 –connector
Input/output RS-232 serial connector for computer interface
0-5 V analog mass concentration output
2 0-5 V analog input signals
Required accessories Vacuum pump (e.g. IA-904) and a suitable vacuum hose (IA-203)
Computer for instrument control
Sample conditioning system
Computer requirements Pentium III processor, MS-WINDOWS 2000™ SP4, XP™, Vista™  or 7™.
Pump requirements 7 m³/h at 100 mbar



Based on well-known ELPI™ technology, the Dekati® Mass Monitor consists of a corona charger complete with on-line particle density measurement, and an inertial 6-stage impactor with electrical detection. A diffusion charger is first used to give precisely determined charge to all measured particles. Charge level is close to saturation charge level for each particle size. After charging region a static electrical field is used to deflect smallest particles to the charger mobility electrode; an electrometer is used to measure this current. This construction is used as a particle mobility size analyzer.

After charger particle size classification is accomplished in a 6-stage inertial impactor. Sensitive electrometers are connected to impactor collection sensors and particles impacting to a corresponding collection surface generate an electrical current for that electrometer. This current is proportional to the amount of particles in each size range. Combining the particle mobility size information from the charger and the aerodynamic size from the impactor enables calculation of the effective density of the particles required for conversion from measured current values to particle mass concentration.


Vacuum pumps
DP25 230V/50Hz EUR, for 10 and 30 lpm impactor
DP25 100V/50Hz JPN, for 10 and 30 lpm impactor
DP25 115V/60Hz USA, for 10 and 30 lpm impactor
Sample conditioning and dilution
Dekati® Diluter for aerosol dilution
FPS-4000 for vehicle exhaust and combustion process sample conditioning and dilution FPS-4000
DEED – Dekati® Engine Exhaust Diluter DEED-100
Dekati® Axial Diluter DAD-100

For more accessories, please contact Dekati Ltd.

Dekati® Mass Monitor brochure

Available in customer pages section:

DMM Manual
DMM Software
Spare part catalogue


Can’t find what you’re looking for?

Contact Dekati technical support: support (at)

Contact Dekati sales: sales (at)


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