Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Pressure And Boiling Point
The boiling point given in tables for a liquid is always referenced to an atmospheric pressure of 1 bar. If the pressure acting on a fluid changes, its boiling point also changes.
Pressure is measured in different units: 1 MPa (mega Pascal) corresponds to 10 bar positive pressure or 145 psi, 1 bar absolute pressure corresponds to 0 bar positive pressure and thus to the ambient pressure (atmospheric pressure).
Water boils at a lower temperature the lower the pressure.
The vapor pressure curves for water and refrigerant R134a show that, at constant pressure, reducing the temperature changes vapor to liquid (in the condenser) or that reducing the pressure causes the refrigerant to change from liquid to vapor (inside the evaporator).
Vapor Pressure Curve Of Water
A - Liquid
B - Gas
C - Vapor pressure curve of water
1 - Pressure acting on liquid in bar (absolute)
2 - Temperature in °C
Vapor Pressure Curve Of Refrigerant R134a
A - Liquid
B - Gas
D - Vapor pressure curve of refrigerant R134a
1 - Pressure acting on liquid in bar (absolute)
2 - Temperature in °C
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.