Newer EC155 models (serial numbers 2000 and greater) take advantage of the new vortex intake technology (U.S. Pat. No. 9,217,692), which significantly reduces the frequency of maintenance required, especially in dustier, more polluted conditions. The new models also have an absolute pressure sensor instead of a differential one, which improves the pressure measurements. Finally, the new design uses a stainless-steel sample cell, which provides added protection against corrosion.
