-22MPaA. What does this capital letter A mean? ? ? What negative pressure means

Absolute refers to absolute pressure; there is no concept of positive or negative values. 0 represents absolute vacuum, while 0.1 MPaA corresponds roughly to atmospheric pressure.

It refers to absolute pressure, but it’s impossible to have a value of -22 MPaA.

-22 is definitely wrong; this value can only be positive

Absolute pressure refers to the true pressure, while gauge pressure is the pressure calculated with reference to the local atmospheric pressure at that time and place; when the pressure of the system being measured is equal to the local atmospheric pressure, the gauge pressure is zero. When the pressure of the system being measured is greater than the local atmospheric pressure at that time, the gauge pressure is positive. Gauge pressure is the pressure measured relative to absolute zero pressure, or the pressure measured relative to a vacuum. Vacuum degree is used to measure the difference between the absolute pressure and standard atmospheric pressure; when the absolute pressure of the system under measurement is lower than the local atmospheric pressure, the difference between that local atmospheric pressure and the system’s absolute pressure constitutes the vacuum degree. The relationship among the three can be expressed by the following equation: When the pressure of the system at that location is greater than the local atmospheric pressure, the absolute pressure of the system = atmospheric pressure + gauge pressure ； 2 When the pressure in the local system at that time equals the local atmospheric pressure, the absolute pressure of the system equals the atmospheric pressure ； 3 The pressure of the local system at that time

I’ve learned it; before I only knew about PSIG