Ambient Air enters the APM541 sampler through an omni-directional inlet designed to provide a clear aerodynamic cut-point for particles larger than 10 microns. The PM10 impactor used in the APM541 is based on designs standardized by USEPA and as such the system complies with international norms for PM10 Samplers. The sampling rate is held constant at 1m3/hr by a suitable critical orifice. The reduced sampling rate allows the sampler to operate continuously for 24 hours even in areas having high PM10 levels. A flow totalizing dry-gas meter has been made an integral part of the instrument to provide an unambiguous measure of the volume of air sampled.

Critical Orifice maintains constant sampling rate throughout sampling    period.

Sampling principle:	Impactor based design as per EPA specifications
Particle Separation :	Omni-directional air inlet with PM 10 separation through an impactor
Sampling Rate :	The sampling rate is held constant at 1m3/hr by a suitable critical orifice. The reduced sampling rate allows the sampler to operate continuously for 24 hours even in areas having high PM10 levels.
Filter media :	Filter holder designed to accept standard 47 mm diameter filter media/PTFE Membrane
Pump :	Low noise, brushless motor driven