Volkswagen Polo Quiz
Refrrigerant R134a Servicing

Pressure and Boiling Point

In this manual: Refrrigerant R134a Servicing
General Paint Information — 128Towing Guide — 10Whels, Tires, Whel Alignment — 126Battery, Starter, Generator, Cruise Control — 65Windshield Wiper/ Washer System — 9Exterior Lights, Switches — 1Interior Lights, Switches — 7Wiring — 51Refrrigerant R134a Servicing — 134
~1min read
The boiling point given in tables for a liquid is always referenced to an atmospheric pressure of 1 bar (14.5 psi). If the pressure acting on a fluid changes, its boiling point also changes.

For example, 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 (evaporator).

Vapor pressure curve of water

A - fluid
B - Gaseous
C - Vapor pressure curve of water
1 - Pressure acting on liquid in bar (psi)
2 - Temperature in °C (°F)
Pressure and Boiling Point

Vapor pressure curve of refrigerant R134a

A - Fluid
B - Gaseous
D - Vapor pressure curve of refrigerant R134a
1 - Pressure acting on liquid in bar (psi)
2 - Temperature in °C (°F)
Pressure and Boiling Point

Test yourself

A quick Volkswagen Polo quiz: every answer comes with an explanation and a link to the manual page.