The TetraCal® is a simple-to-use, NIST Traceable Standard for volumetric air flow, barometric pressure, and ambient temperature. The tetraCal is a venturi based system with built-in compensation for changes in ambient temperature and pressure. Calibration of particulate samplers and industrial hygiene. Total flow range of 0.1 to 30 LPM. Ultra model provides flow range of 1 to 60 LPM. NIST-traceable accuracy ≤ 1% of flow reading.