Mitsubishi Electric PUZ-WZ50VAA Service Manual page 4

[1] R290 Refrigerant Properties
(1) Properties of refrigerants.
R290 refrigerant is classified as class A3 in the safety group of ISO817 because it has low toxicity (class A) and higher
flammability (class 3).
It is highly flammable and MUST be handled safely to prevent fire and explosion.
Chemical formula
Composition (blend ratio wt.%)
Ozone depletion potential (ODP)
Global warming potential (GWP)
Boiling point (°C)
Pressure (MPa) *2
Flammability
*3
Toxicity
*3
*1 Values based on IPCC 4th assessment report
*2 Temperature condition Characteristic value at 50°C
*3 Data from ISO 817:2014
(2) Pressure[MPaG]
As shown in the following table, at the same refrigerant temperature, the saturated vapor pressure of R290 is lower than
that of R32 and about as same as that of R22.
However the design pressure of R290 ATW is 3.2MPaG in order to raise the hot water temperature to 75°C
(It is higher than R22).
So note that the pressure strength required for the tool which is used for R290 is not the same as that of R22.
Temperature (°C)
-20
0
20
40
60
80
(3) Flammability
As shown in the following table, R290 ignites with much less concentration and energy than R32.
In addition, it burns explosively unlike R32. In other words, when handling the products and cylinders containing the
R290, there is a higher probability of causing a larger explosion or fire than the R32.
Therefore, stricter safety measures are required than R32 refrigerant.
Flammability *1
LFL (Vol.%) Lower Flammable Limit
UFL (Vol.%) Upper Flammable Limit
Minimum ignition energy (mJ)
Burning velocity (cm/s)
Ignition temperature (°C)
Maximum allowable the temperature (°C)
EN378-2:2018 *2
*1 Data from ISO 817:2014
*2 Data from EN378-2:2018
(4) Smell
The propane for a gas stoves generally has an odour, but the propane used as a refrigerant for this products has NO
smell.
In other words, it is not possible to notice by the odour whether or not the refrigerant is leaking, so you should always
check it with a leak detector when working.
OCH816
R290
C H
3 8
Single composition
0
<3
*1
-41.8
1.71
Higher Flammability
(Class 3)
Lower Chronic
Toxicity
(Class A)
R290 R32
0.14 0.3
0.47 0.71
0.84 1.37
1.37 2.38
2.12 3.84
3.13 -
R290
Higher Flammability
(Class 3)
1.8
9.5
0.246
38.7
470
370
R32
CH F CH
2 2
Single composition
0
675
-51.7
3.14
Lower Flammability
(Class 2L)
Lower Chronic
Toxicity
(Class A)
R410A R22
0.3 0.14
0.7 0.4
1.35 0.81
2.32 1.43
3.73 2.33
- -
R32
Lower Flammability
(Class 2L)
13.3
29.3
15
6.7
648
548
4
R410A R22
F /CHF CF CHICF
2 2 2 2
R32/R125R
Single composition
(50%/50%)
0 0.055
2088 1810
-51.5 -40.8
3.07 1.94
No Flame No Flame
Propagation Propagation
(Class 1) (Class 1)
Lower Chronic Lower Chronic
Toxicity Toxicity
(Class A) (Class A)
2