Testo - Model MD19-3E - Raw Gas Diluter
MD19-3E (PND1) - The new MD19-3E is a re-engineered diluter. It keeps all advantages which a rotary diluter system brings with, the dilution ratio ranging from 1:15 up to 1:3000. Accurate dilution of aerosols usually requires precise and stable mass flow control, specially if large dilution ratios and ranges are requested. Our newly improved and long time proven rotating disc method of dilution avoids several problems of the conventional dilution technique such as frequent weekly linear checks or nozzle clogging.The mobile dilution head method allows to dilute the nearest possible to the aerosol source. This flexibility in the probe intake saves costly add-ons to avoid particle coagulation. A PMP compliant cyclone is optionally delivered with a regulated 2.5 µm cut off cyclone.
Usually instruments which determine nanoparticle number concentrations have specific measuring ranges, With the rotating disk diluter it is possible to adapt particle number concentrations to the measuring range of the applied particle sensor. Depending on fuel and combustion parameters like air humidity, temperatures and residual times, combustion generated aerosols mostly do not only contain CO2 and solid particles but also water vapor and other volatile components which may condense out if the temperatures drop to ambient conditions, resulting in liquid particles which may damage or pollute the measuring sensors. In the MD19-3E diluter head these components are at first evaporated and then diluted. Since the exhaust raw gas pressure can go up to 300 mbar (at 200°C) it is now possible not only to measure downstream the particle filter but also upstream the filter which eases considerably the test bench installation.
The fully remote system allows a much better flexibility, no need to start and stop manually the pump. The complete system is now computer remote controlled. The plug-in operation with the thermo-diluter ASET15-1 (thermodiluter) is ensured. The diluter can be assembled from its stand alone version into the ASET15-1 to build a complete compliant VPR (ECE-R83 or Euro 5b/6).
The new cyclone is much smaller and does not need an extra pump. The lightweight cyclone contributes also to the reduction of the general size of the diluter head. The weight reduction of the global system will allow improved handling, flexibility and ultimately save installation and maintenance costs.