It is an electronic device used to measure the pH (acidity or alkalinity of a substance). This device has special electrodes that, when placed in a liquid, display its pH number on its screen. The accuracy and speed of this tool is higher than conventional acid and base detectors and therefore it is widely used in various industries. This device was first invented in 1936 by the American chemist Arnold Orville Beckman. Model pH meter 220 is a professional device that in addition to measuring the pH level can also display the temperature to its user