Volkswagen Polo Service & Repair Manual: Critical Point
| Vehicle air conditioning systems make use of the
vaporization and condensation process. In this case, one works
with a substance which boils easily, designated as refrigerant. |
| The refrigerant employed is tetrafluoroethane R134a, which
boils at -26.5 °C (-15.7 °F) at a vapor pressure of 1 bar (14.5
psi). |
| The critical point (critical temperature and critical
pressure) is that above which there is no longer a boundary
between liquid and gas. |
| A substance above its critical point is always in the
gaseous state. |
| At temperatures below the critical point, all types of
refrigerant in pressure vessels exhibit both a liquid and a gas
phase, i.e. there is a layer of gas above the liquid. |
| As long as there is still gas present in the container next
to the fluid, pressure is dependent on ambient temperature.
Refer to
→ Chapter „Refrigerant R134a Vapor Pressure Table“. |
 Note
| Different types of refrigerant are never to be mixed. Only
the refrigerant designated for the corresponding A/C system may
be used. |
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Vehicle air conditioning systems make use of the
vaporization and condensation process. In this case, one works
with a substance which boils easily, designated as ref ...
Vehicle air conditioning systems make use of the
vaporization and condensation process. In this case, one works
with a substance which boils easily, designated as ref ...
Other materials:
Wires with Cross Section up to 0.35 mm 2,
Repairing
Special tools and workshop equipment
required
Crimping Pliers - .35-2.5mm -VAS1978/1A-
Wiring Harness Repair - Crimping Head - .35-2.5mm
-VAS1978/1-1-
When repairing wires with a cross- ...
Introduction
This chapter contains information on the following subjects:
→ Handling wheels and tyres
→ Rims
→ New wheels and tyres
→ Tyre pressure
→ Tread depth and wear indicators
→ Tyre damage
→ Spare wheel or temporary spare wheel
â ...
Flat Spots
What is a Flat Spot From Standing?
Terms like flat portion, flattening, are also used as a term
for flat spots from standing.
Flat spots from standing cause vibration, like an
incorrectly balanced wheel. It is important ...
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Refrigerant R134a Physical Data
Refrigerant R134a Environmental Information