TSI offers two Primary Calibrator Models for calibrating pumps and any other air sampling instruments that draw an active air sample. These small, portable, battery-operated units are lightweight and easy to use. Volumetric flow rate is displayed continuously, making real-time pump adjustment, calibration and periodic flow checks fast and easy. These Primary Calibrators are temperature-compensated and pressure-corrected to calculate volumetric flow rate at an accuracy within 2% of reading.