Get Technical data -> 6.2.14 Charge factor of refrigerant R1234yf Guide for Volkswagen Touran 4 Door Second Generation (2015-2022)

Arteon 2018 ➤ , Atlas 2017 ➤ , CC 2012 ➤ , Caddy 2016 ➤ , Crafter 201 ...

Air conditioning systems with refrigerant R1234yf - General information - Edition 07.2017

♦ If the refrigerant is contaminated, e.g. with chlorine com‐

pounds or by the influence of UV light, metals and also plastics

developed and tested for this refrigerant and refrigerant oil can

be corroded. This can lead to blockages, leaks and deposits

on the air conditioner compressor piston.

♦ Certain metals can be corroded by R1234yf refrigerant (e.g.

finely distributed aluminium, zinc, magnesium)

6.2.11

Critical temperature / critical pressure of

R1234yf refrigerant

Up to a gas pressure of 32.82 bar (which is equivalent to a tem‐

perature of 94.7°C), refrigerant evaporates at the surface in a

quantity that, combined with particles of vapour, returns it to liquid

again. Above this temperature / pressure there is no longer a sur‐

face separating the liquid and gas.

6.2.12

Water content of R1234yf refrigerant

♦ Only very small amounts of water are soluble in liquid refrig‐

erant. On the other hand, refrigerant vapour and water vapour

mix in any ratio.

♦ Any water in the refrigerant circuit will be entrained in droplet

form once the dryer in the receiver or reservoir is full (once it

has absorbed approx. 7 g of water). This water flows as far as

the expansion valve nozzle or the restrictor and turns to ice.

The air conditioner no longer provides cooling.

♦ If the existing water at the regulating valve of the air conditioner

compressor turns to ice, a variety of complaints may be made

depending on the design of the air conditioner compressor

(either the air conditioning system stops cooling or the air con‐

ditioning system cools to such a degree that the evaporator

ices over).

♦ Water destroys the air conditioner because at high pressures

and temperatures it can combine with other impurities to form

acids.

6.2.13

Flammability / decomposition of

R1234yf refrigerant

♦ In certain concentrations in the ambient air, R1234yf refriger‐

ant is flammable.

♦ R1234yf begins to decompose when exposed to flames and

glowing or hot surfaces. Even UV light causes refrigerant to

break up (UV light is part of normal sunlight, it is also encoun‐

tered e.g. during electrical welding), which releases poisonous

fission products that must not be inhaled. However, these

chemicals irritate the mucous membranes, giving adequate

warning of their presence.

♦ During decomposition, certain hazardous products such as

carbon monoxide, hydrogen fluoride and / or hydrogen halide

can be released.

6.2.14

Charge factor of refrigerant R1234yf

♦ When charging compressed gas containers (returnable cylin‐

ders, recycling cylinders etc.), observe the applicable regula‐

tions, technical rules and legislation.

♦ Never overcharge compressed gas containers (returnable cyl‐

inders, recycling cylinders etc.). The gas cushion (expansion

space) of overcharged compressed gas containers is too

small to accommodate expansion of the fluid caused by a rise

in temperature. Risk of bursting.

6. Basic technical and physical properties

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Arteon 2018 ➤ , Atlas 2017 ➤ , CC 2012 ➤ , Caddy 2016 ➤ , Crafter 201 ...

Air conditioning systems with refrigerant R1234yf - General information - Edition 07.2017

♦ To ensure safety, only use compressed gas containers fitted

with a safety valve.

♦ Returnable and recycling cylinders must be weighed on suit‐

able scales during charging, or a method of charging by vol‐

ume must be employed to ensure that the permissible weight

of the filling specified on the tank/container is not exceeded.

The maximum permissible filling volume is 80% of the maxi‐

mum refrigerant volume of the filling weight specified on the

returnable and recycling cylinder or 70% of the maximum filling

volume (charge factor, the smaller of the values always ap‐

plies respectively). Reason: There is no way of absolutely

ruling out refrigerant oil being filled into the returnable and re‐

cycling cylinder along with the refrigerant.

♦ There must be space both for liquid and vapour in a container.

As the temperature rises, the liquid expands. The vapour-filled

space becomes smaller. At a certain point, there will only be

liquid in the vessel. Beyond this, even a slight increase in tem‐

perature causes great pressure to build up in the vessel as the

liquid attempts to continue expanding despite the absence of

the necessary space. The resultant force is sufficient to rup‐

ture the vessel. To prevent containers from being over‐

charged, regulations governing the storage of compressed

gases specify how many kilograms may be charged into a

container for every litre of container volume. This charge factor

multiplied by the internal volume gives the permissible charge

quantity. The charge factor for refrigerant used in vehicles is

1.15 kg/litre.

♦ Since contaminated refrigerant could have a different density

than pure R1234yf refrigerant, the maximum permissible

charge factor must always be observed.

6.2.15

Evidence of leaks in a refrigerant circuit

with R1234yf refrigerant

♦ The refrigerant circuit could develop leaks, for example, from

the use of unsuitable or contaminated refrigerant or untested

materials in unsuitable components.

♦ Since a small leak will involve only small quantities of refrig‐

erant, evidence of leaks should be sought using an electronic

leak detector or by introducing a leak detection additive to the

refrigerant circuit. Electronic leak detectors can detect leakage

rates of less than 5 grams loss of refrigerant per year.

Note

Use must however be made of leak detectors designed for the

composition of the respective refrigerant. For example, leak de‐

tectors for R12 refrigerant are not suitable for R1234yf refrigerant

as these leak detectors do not always respond. Even leak detec‐

tors that are designed just for R134a refrigerant are not suitable

for R1234yf refrigerant because R1234yf refrigerant has a differ‐

ent chemical structure than R134a. Subsequently, these leak

detectors only respond to high concentrations of refrigerant in the

air or not at all ⇒ Electronic parts catalogue .

6.2.16

Analysis of refrigerant R1234yf

For operation of the air conditioning system, it is important that

the refrigerant used has a certain degree of purity.

Rep. gr.00 - Technical data

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Technical data -> 6.2.14 Charge factor of refrigerant R1234yf for Your Volkswagen Touran 4 Door Second Generation (2015-2022)

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