The vacuum gauge is the instrument for measuring pressures lower than atmospheric pressure and always works in connection with a vacuum pump or a compressor. There are two types of vacuometers: U-tube and electronic.
U-TUBE VACUOMETER
The U-tube vacuometer, sometimes also called "U-type manometer", can accurately measure up to 759.5 mm / Hg of vacuum. It is constructed with a U-shaped glass tube, where mercury is placed, which rises or falls in level according to the pressure created by the vacuum pump or compressor.
It is widely used in fixed installations in laboratories and workshops. Because it is fragile and impractical for transportation, it is not recommended for general refrigeration use.
ELECTRONIC VACUOMETER
The electronic vacuometer is used to accurately measure negative pressures, practically reaching absolute vacuum, that is, between 759 mm and 760 mm / Hg. This type of vacuum gauge is used by the refrigeration and air conditioning mechanic because it has a reading accuracy for pressure below 0.5 mm Hg, that is, 500 m Hg and easy to transport, today there is already an electronic vacuum gauge in the shape and size of the conventional vacuum gauge, indication and by lighting an LED that lights where it has a graduation indicating the vacuum reached.
