A vacuum pressure gauge is a type of pressure measuring instrument that uses elastic elements as sensitive components. In recent years, it has been widely used in many fields, with the advantages of convenient detection, simple operation and high precision. Then, how to read negative pressure on a vacuum pressure gauge? How to adjust parameters? Let's answer these two questions today. ### How to read negative pressure on a vacuum pressure gauge #### How to read this kind of vacuum pressure gauge Negative pressure (vacuum): refers to the pressure lower than atmospheric pressure, with atmospheric pressure as the reference. Taking a refrigerant pressure gauge as an example: - The outer black ring indicates the corresponding temperature of refrigerant CF12 under a certain pressure; - The outer red ring indicates the corresponding temperature of refrigerant CF22 under a certain pressure; - The inner red ring indicates pressure units (negative pressure is in in.Hg (inches of mercury), and positive pressure is in Lb/in² (psi, pounds per square inch)); - The inner black ring indicates pressure in MPa (megapascal, 1MPa = 10kgf/cm²); The innermost two rings both indicate pressure but in different units. The outermost two rings indicate the temperature of different refrigerants under the corresponding pressure. Generally speaking, we only need to look at the inner ring for pressure, choosing MPa or PSI according to personal habits, while the values on the outer rings are only for checking the temperature of refrigerant media under the corresponding pressure. #### How to read the readings of a vacuum pressure gauge inHg stands for inches of mercury, bar is bar, MPa is megapascal (1MPa = 145psi), and PSI is pounds. It is easier to understand pressure by looking at MPa. "R" and numbers are codes for refrigerant gauges. There is a certain corresponding relationship between pressure and temperature on a refrigerant pressure gauge. In engineering, people often refer to pressure in "kg" which means kg/cm², while pressure gauges are often marked in MPa. 1N/m² = 1Pa, 1kg = 9.8N, 1m² = 10000cm², so 1kg/cm² = 98KPa = 0.098MPa. In engineering, people approximately take 1MPa = 10kg/cm². The range of a vacuum gauge starts from zero, while that of an absolute pressure gauge starts from -1Bar. Pressure gauges are widely used in pipelines and containers for transporting gases and liquids to measure the pressure of media such as liquids, gases, and steam that are non-explosive, free of crystals, non-condensable solids, and non-corrosive to alloys. They have the advantages of small size, safe and reliable performance, and clear display. Pressure has two expression methods: one is the pressure expressed with absolute vacuum as the reference, called absolute pressure; the other is the pressure expressed with atmospheric pressure as the reference, called relative pressure. Since most pressure measuring instruments measure relative pressure, relative pressure is also called gauge pressure. When the absolute pressure is less than atmospheric pressure, it can be expressed by the value that the absolute pressure in the container is less than one atmospheric pressure, which is called "vacuum degree". ### How to adjust parameters of a digital display vacuum pressure gauge The setting sequence of a digital display vacuum pressure gauge is as follows: Power on → Measurement mode → Zero correction → Function setting → Measurement mode. After the product is powered on, it automatically enters the pressure measurement mode. For the first use, please operate in the following sequence. The debugging steps of a digital display air pressure gauge are as follows: 1. Connect the power supply: Connect the digital display air pressure gauge to the power supply (usually 220V/50HZ) and confirm that the power indicator of the digital display air pressure gauge is on. 2. Confirm sensor connection: Ensure that the sensor of the digital display air pressure gauge is connected correctly. If the sensor is not connected or connected incorrectly, the digital display air pressure gauge will not read the pressure correctly. 3. Set the unit: Select the appropriate pressure unit as needed, usually psi, bar, or kPa. 4. Adjust zero: In the absence of pressure, press the "zero" or "ibration" button on the digital display air pressure gauge to reset the reading to zero. If necessary, use a screwdriver to adjust the zero adjustment screw on the back of the digital display air pressure gauge. 5. Perform calibration: Adjust according to the calibration screw as needed. Usually, it is necessary to use a standard pressure gauge or weighing equipment, input the standard value into the digital display air pressure gauge, and calibrate according to the difference between the two values. 6. Complete debugging: After calibration, confirm that the reading of the digital display air pressure gauge is accurate. It should be noted that when debugging the digital air pressure gauge, operate carefully to avoid incorrect operation leading to inaccurate measurement. During the debugging process, strictly abide by relevant safety regulations to ensure personal safety. If you are not familiar with the debugging process, it is recommended to seek help from professionals. Source: Compiled from the Internet