HFO-1234yf – Safety when ex

to ignition sources

Holtappels, K. ; Schröder, V.

BAM Federal Institute for Materials Research and Te

Hoffmann, G.; Plehn, W.

UBA Federal Environment Agency
2

Contents 

1. Motivation2. Safety Characteristics3. Case study – Explosion regio4. Case study – HF formation5. Case study – Leakage6. Conclusions
3

Motivation 

•Hazard assessment cannot take place b

on a single individual test series or safecharacteristic.

•Various systematic scenarios ("inciden

be analyzed.

•Finally only a holistic hazard analysis c

an accurate evaluation. 
4

Contents 

1. Motivation2. Safety Characteristics3. Case study – Explosion regio4. Case study – HF formation5. Case study – Leakage6. Conclusions
5

Safety Characteristics

Already known and published safety charac

(MSDS Honeywell, Version 1 from 11/10/2• Flammability limits: 

LEL = 6.2 vol%UEL = 12.3 vol%

• Minimum ignition temperature: 

MIT = 405 °C
6

Safety Characteristics

• Determined according to existing standa

(EN, ASTM ...) 

• Strongly influenced by experimental para

 initial temperature and pressure vessel size and dimension ignition source (type and strength) direction of flame propagation turbulence effect of inert admixtures oxygen concentration flammable mixture composition and many more ...
7

Contents 

1. Motivation2. Safety Characteristics3. Case study – Explosion regio4. Case study – HF formation5. Case study – Leakage6. Conclusions
8

Explosion regions

Effect of hydrocarbons (e.g. crack products of oil):

0 5 10 15 20 25 30 35 4

amount of inert gas respectively refrigerent [vol%]

02468

10121416

amount of ethane [vol%]

explosion region of ethane-explosion region of ethane-

 explosion region of ethane

explosion region

ETHAN_IG_ALLE_LUFT_XY_DIN51649 | 23.5.2010
9

Contents 

1. Motivation2. Safety Characteristics3. Case study – Explosion regio4. Case study – HF formation5. Case study – Leakage6. Conclusions
10

HF formation

Determination of the amount of HF when refrigereare exposed to hot surfaces:• 3-dm3 stainless steel vessel (German steel code 1

• pre-mixed homogeneous mixtures• 10 min exposure time• recording of p-t- and T-t-histories (ignition phen

• 500 ml gas sample for IC analysis
11

HF formation

UBA 32 20.0 + oil 80.0 500 yes UBA 31 10.0 + oil 90.0 500 yes UBA 30 5.0 + oil 95.0 500 no UBA 28 20.0 + oil 80.0 350 no UBA 27 10.0 + oil 90.0 350 no UBA 26 5.0 + oil 95.0 350 no UBA 18 20.0 80.0 500 yes UBA 17 10.0 90.0 500 yes UBA 16 5.0 95.0 500 no UBA 09 20.0 80.0 350 yes UBA 08 10.0 90.0 350 yes UBA 07 5.0 95.0 350 yes UBA 06 20.0 80.0 200 no UBA 05 10.0 90.0 200 no UBA 04 5.0 95.0 200 no 

HFO1234yf air

Explosio

yes / no

Temperature 

[°C]

Mixture composition [mol-%]

Test no.

HFO1234yf-ai
12

Contents 

1. Motivation2. Safety Characteristics3. Case study – Explosion regio4. Case study – HF formation5. Case study – Leakage6. Conclusions
13

Release to a hot metal surface and HF det

• 200-dm3 plastic box

• pre-heated metal block (tmax = 1200 °C)

• release of 50 g of pure refrigerents and mixture

refrigerents with oil

• 500 ml gas sample for IC analysis

Leakage
14

Leakage

Release to a hot metal surface and HF determinati
15

Leakage

Release to a hot metal surface and HF determinati
16

Leakage

Release to a hot meand HF determinatio

Box 17 R134a;50 g * 900 no **** Box 16 R134a;51 g * 800 no **** Box 15 R134a;51 g * 700 no Box 14 R134a;52 g * 600 no Box 13 HFO1234yf; 50 g * 500 no Box 12 R134a; 51 g * 500 no Box 11 HFO1234yf; 50 g 500 no Box 10 R134a;52 g 500 no Box 09 HFO1234yf; 51 g * 600 yes Box 08 HFO1234yf; 52 g * 500 no Box 07 HFO1234yf; 54 g 500 no Box 06 HFO1234yf; 55 g 700 no Box 05 HFO1234yf; 52 g 800 no Box 04 HFO1234yf; 54 g 900 yes Box 03 R134a;52 g 900 no Box 02 R134a; 53 g 800 no Box 01 R134a; 56 g 700 no 

Explosion 

yes / no

Temperature 

of metal [°C]

Refrigerant and 

released mass Test no.
17

Release to a model volume:

• 200-dm3 plastic box

• burning candle• release of 50 g of pure refrigerents or• smaller leakage rates (layer of refrigerent on th

• detection tube for HF analysis

Leakage
18

Leakage Release to a mode

Flame extinguished af360 s. CO2 (mass not determined) V 06Flame larger after 120 extinguished after 350 

R134a (mass not determined) V 05

Blue flame after 500 sheight 10 cm. Flame extinguished after 18 m

HFO1234yf (mass not determined) V 04

Blue flame after 30 s, increasing with amounrefrigerant. Flame extiafter 70 s. 

V 03 HFO1234yf, 46 g

Flame larger after 30 sextinguished after 70 s

V 02 R134a; 52 g

Flame extinguished af50 s. CO2 (mass not determined) V 01

Observation Refrigerant and released mass Test no.
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Leakage Release to a mode

V 03: Release of 46 g HFO1234yf withi

HF > 
20

Leakage Release to a mode

V 04: Release of HFO1234yf (picture after 3

HF > 90 ppm!
21

Leakage

Release to passenger compartment: Ignition of HFO1234yf low stream and HF determi• real car prepared for refrigerent release throug

at front passenger side

• First ignition source: high voltage spark• Second ignition source: match igniter• Third ignition source: open flame (propane burn• HF analysis after activation of each ignition sou

places (seat behind front passenger, seat behindriver)
22

Leakage

Release to passenger compartment: Ignition of HFO1234yf low stream and HF determi

Spark igniter and match igniterno ignition and no HF detected
23

Leakage

Release to passenger compartment: Ignition of HFO1234yf low stream and HF determi

Open flame: no ignition or flame phenobut HF concentration > 90 ppm!
24

Leakage

Release of total amount HFO1234yf of MAC to pascompartment: •Release of 900 g HFO1234yf through air condition 

passenger side•Three match igniter•Three thermocouples and one pressure transduce•Online O2-analysis close to first ignition source

•Six fans for homgenisation of gas mixture•Webcam for inside video record•Two camcorder
25

Leakage

Release of total amount HFO1234yf of MAC to pascompartment: 

pres

webcam

thermocouple

pipe for O2-analysis
26

Leakage

Release to motor compartment, directed to part of system: 

One of three mpipe for O2-ana

Inlet pipe for HFO1234yf release
27

Leakage

Release to motor compartment, directed to part of system – video sequence
28

Leakage

Release to motor compartment, directed to part of system – Corrosion of windows due to HF
29

Leakage

Release to motor compartment, directed to part of system: 
30

Contents 

1. Motivation2. Safety Characteristics3. Case study – Explosion regio4. Case study – HF formation5. Case study – Leakage6. Conclusions
31

Conclusions

• Presented case studies are only examples. Holi

analysis is much more extensive. 

• Flammability of HFO1234yf is strongly depende

released mass and rate 

• Flammability of HFO1234yf is not a barrier for 

• Preventive measures are necessary (filling stat

stations, transport as well as storage of substa

• Leaking MAC Transport of cars as dangerous 

• Possible HF formation after contact to hot surfa

flames.

• HF concentration are often higher than 90 ppm
32

Thank you very much for your attention

are any questions left don`t hesitate to 
33

HF formation HFO1234yf-ai

0123456789

10

0 50 100 150 200 250 

time in s

pressure in bar

pressutemper

UBA_09: 20 % HFO1234yf
34

HF formation

UBA 25 20.0 + oil 80.0 500 no UBA 24 10.0 + oil 90.0 500 no UBA 23 5.0 + oil 95.0 500 no UBA 22 20.0 + oil 80.0 350 yes UBA 21 10.0 + oil 90.0 350 no UBA 20 5.0 + oil 95.0 350 no UBA 15 20.0 80.0 500 no UBA 14 10.0 90.0 500 no UBA 13 5.0 95.0 500 no UBA 12 20.0 80.0 350 yes UBA 11 10.0 90.0 350 no UBA 10 5.0 95.0 350 no UBA 03 20.0 80.0 200 no UBA 02 10.0 90.0 200 no UBA 01 5.0 95.0 200 no 

R134a air

Explosio

yes / no

Temperature 

[°C]

Mixture composition [mol-%] Test no.

R134a-air mix
35

Leakage

Enclosed Space Ignition Testaccording to model regulations for transport of da(5th revisded edition of Manual for Tests and Crite
36 ESI 11 HFO1234yf, liquid phase, no flow limitation Ignition 

Ignition 

HFO1234yf, gas phase, no flow limitation (repetition of ESI 09) ESI 10

ESI 09 HFO1234yf, gas phase, no flow limitation Ignition ESI 08 HFO1234yf; liquid phase; 54 g Flame sESI 07 HFO1234yf; gas phase; 52 g Flame sESI 06 HFO1234yf + 3% oil; liquid phase; 52 g Flame sESI 05 HFO1234yf + 3% oil; gas phase; 55 g Flame sESI 04 R134a + 3% oil, liquid phase, 51 g No visibESI 03 R134a + 3% oil, gas phase, 47 g No visibESI 02 R134a, liquid phase, 50 g No visibESI 01 R134a, gas phase, 56 g No visib

Refrigerant, aggregate state and released mass Test no.

Leakage Enclosed spac