The Escort ELF® sampling pump can be used for personal and area sampling. It features a state of the art electronic laminar flow sensor to keep the 1 to 3 lpm constant flow accurate +/- 2.5% over eight hours, automatically compensating for changes in battery voltage, temperature, altitude, and sample load. An internal secondary standard calibrates the pump continuously, so it only needs to be checked against a primary standard once a month. UL approved and availiable as a single pump or as a five pump.