Compact, environmentally friendly water-based condensation particle counters are suitable for use in clean rooms, environmental science applications, high purity gas systems, and other air sampling applications. Manufacturer says the instruments use novel single-flow mixing technology to provide superior counting at high particle concentrations. The use of water along with an efficient HEPA exhaust filter makes these systems environmentally friendly. Available in two models, each designed for different duty levels: one has a sampling flow of 3.0L/min and a detection limit of 12nm and the other has a sampling flow of 1.0L/min and a detection limit of 8 nm. Low maintenance requirements and robust design allow both to carry out extended cycles of operation providing counts of from 1 to 10 million particles per second across a wide range of concentrations.