vacuum gaugeTesto Inc. introduced its new Testo 552 digital vacuum gauge to confirm the evacuation of air-conditioning, heat pump and refrigeration systems. Unlike other vacuum gauges, the company said the Testo 552 requires no cleaning, nor is it susceptible to contamination from oils. Officials also said the pressure sensor delivers accuracy to plus or minus 10 microns. The gauge is equipped with a large backlit display. Additional features include a battery life up to 2,400 hours, a high-limit alarm, and display of water evaporation temperature.

Testo Inc., 40 White Lake Road, Sparta, NJ 07871; (800) 227-0729;