Pressure Gauge Display
Pressure is measured in different units: 1 MPa (mega Pascal) corresponds to 10 bar (145.04 psi) positive pressure or 145 psi. 1 bar (14.5 psi) absolute pressure corresponds to 0 bar (0 psi) positive pressure and thus to the ambient pressure (atmospheric pressure).
Certain pressure gauges may have one or more temperature scales in addition to the pressure scale. The scale values for refrigerant R744 are assigned according to the vapor pressure table. The correlation between the temperature and pressure is only applicable up to the critical temperature of 31.1 °C (88 °F) and when the refrigerant circuit is filled per specification and the motor is off.
Various measuring devices can be used to measure the pressure. With pressure gauges, the measured pressure is usually displayed immediately. With electronic pressure measuring equipment, the pressure is measured, for example, by a pressure sensor and is typically shown on a display in the selected unit of measurement. Refer to the A/C Service Station Operating Instructions.
- The pressure gauges make is possible to perform the following checks and measurements. Refer to PRESSURE GAUGE USES .