The Testo 552 is a digital vacuum measuring instrument for the evacuation of refrigeration systems and heat pumps. It measures even the smallest absolute pressures and provides highly precise information on the status of the dehumidification of a system (removal of foreign substances, incl. oils or foreign gases). The Testo 552 is the only digital vacuum measuring instrument whose absolute pressure sensor, in contrast to other sensor technologies, no longer needs to be serviced, and still provides highly accurate measurement results. Thanks to the battery life of up to 2400 hours with two conventional AA batteries, you can use the testo 552 in continuous operation for 100 days without changing the battery. Its robust construction makes it suitable for daily use, and protects from dirt and water. Maintenance-free absolute pressure sensorClick to Zoom 2400 hours' battery life Measurement of H2O evaporation temperature Optical alarm when limit values are exceeded Vacuum measuring range: 1100 - 0 mbar / 825080 - 0 micron Sensor overload absolute: 6 bar / 87 psi (relative: 5 bar / 72 psi) Vacuum resolution: 0.01 hPa / 10 micron Vacuum precision: 0 to 1.33 hPa / 0 to 1000 micron: up to ±10 micron 0 to 200 hPa / 0 to 150000 micron: ± 0.3% FS = ±0.6 hPA 200 to 1100 hPa / 150000 to 825080 micron: ±0.3% FS = ±3.3 hPa Parameter: mmHg, Torr, mbar, hPa, micron, inH20, inHg, Pa Sensors: 1 x absolute pressure sensor Battery life: 2,400 h (2x AA), (approx. 130 h with background illumination activated) Connections: 2 x ¼” SAE / 1x MiniDin (testo 570)