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Industry 3 Year Evaluation of low

global warming potential refrigerant

HFO-1234yf

MACS January 21, 2010

William Hill
2

SAE CRP History

 CRP ARCRP [Alternative Refrigerant CRP]

 Started in April 2001 and phase II completed in Nov., 2004

 Covered improved R134a, R744 [several iterations], R290

[secondary loop], and R152a

 IMAC [Improved Mobile Air Conditioning] CRP

 Started in April, 2004 and completed in June, 2006

 Covered all sorts of improvements for R134a systems

 CRP150

 Started in Oct., 2006 and completed in Aug., 2007

 Covered various blend refrigerants from various suppliers

 CRP1234 Proposed in October, 2007 for HFO-1234yf

 Phase 1 completed in Feb, 2008

 Material evaluations completed in Sept., 2008

 Phase 2 completed in Apr, 2009

 Phase 3 completed in Nov, 2009
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HFO-1234yf Cooperative

Research Program

 Research was conducted over the last two years

at international laboratories to get the best

available expertise and to guarantee common

worldwide acceptance

 Issues Investigated include:

 Safety and risk assessment

 Air-conditioning system efficiency and performance

 Material compatibility

 Flammability

 Toxicity

 Extensive testing at third-party facilities did not identify

significant risks for the use of HFO-1234yf in mobile airconditioning systems.
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HFO-1234yf Cooperative

Research Programs

 Cooperative Research Programs (CRP) have

been sponsored by automobile manufacturers

and Tier One/Two Suppliers

 Global Vehicle OEMs

 Audi, BMW, Chrysler, Daimler, Fiat, Ford/Volvo,

General Motors/Opel, Hyundai, Porsche, PSA, Renault,

Shanghai Automotive, Tata, Jaguar Land Rover,

Toyota, VW

 Tier One/Two Suppliers

 DuPont, Honeywell, Conti Tech, Dayco, Delphi, Denso,

Doowan, Dow, Freudenberg, Goodyear, Hutchinson,

Maflow, Egelhof, Parker Hannifin, Sanden, Trelleborg,

Valeo, Visteon
5

Safety and Risk Assessment

 Detailed Fault Tree Analysis [FTA] has been

completed with input from major OEMs from

around the world

 The following scenarios have been considered:

 Potential risks due to refrigerant flammability

 Accidental releases during vehicle operation and service

 Potential risk due to refrigerant toxicity

 Accidental releases during vehicle operation and service

 Potential risk due to decomposition products

 Accidental releases during vehicle operation and service

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Safety and Risk Assessment

Extensive Fault tree scenarios

 Vehicle use in Field Scenarios

 Component Failures

 Vandalism

 Vehicle Collision Scenarios

 Occupant

 Good Samaritan

 Service Scenarios
7

CRP Methodology

 Uses Fault Tree Analysis methods for key exposure

scenarios

 Vehicle exposures

 Repair exposures

 Qualitative evaluation of other scenarios with limited

impact

 Assembly plant workers

 Parking garages, tunnels

 Ecological impacts

 Fault Tree Inputs are based on measured data, public

databases, and consensus by the Vehicle Makers

HVAC and Safety engineers

 Results are compared to other non-AC related

automotive risks
8

Risk Assessment Input Data:

Concentration Measurement Data

 Refrigerant Concentration after Accidental Release

 Vehicle Makers concentration measurements in vehicles

(4 Vehicle Makers, different vehicle types)

 Health-based limit never exceeded

 LFL exceeded in a few instances with severe collision

scenarios (typically in recirculation mode, low blower, near

floor, generally away from possible ignition sources)

 Refrigerant concentration alone is not enough to produce a risk of

refrigerant ignition or HF exposure

 Sufficient refrigerant and sufficient ignition source must be present at

the same time and location, occupant must also be present in limited

area where ignition occurs

 All measured concentrations and the scenarios leading to

these were considered in the Fault Tree Analysis

Ignition and thermal decomposition risks addressed in FTA
9

Typical Concentration in Vehicle Interior

with Corrosion leak

 Interior cabin

corrosion leaks do

not develop

refrigerant

concentrations of

concern

 Corrosion cases

excluded from

FTA based on

actual vehicle

measurements

(collected with

vehicle switched

on and off)

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

7.0%

0 50 100 150 200 250 300 350 400 450

Time, minutes

C

o

n

c

e

ntr

atio

n, V

ol%

Driver's Foot

Passenger's Foot

Driver's Lap

HFO-1234yf

Corrosion Leak (0.1 mm)

40  ̊C Ambient

Typical MidSize Sedan (2.5 m3)

575 g charge

Vehicle Off

LFL

Measurements of cabin HFO-1234yf concentration for corrosion leaks did not

exceed 2%

Full system

discharge
10

Toxicity Input Data

Toxicity

Toxicity testing by TNO, WIL and

Hamner Institutes

 Based on studies and results of Phase I

and II risk assessments, exposures are not

of concern from the standpoint of

refrigerant toxicity, therefore refrigerant

toxicity was not addressed via FTA in

Phase III

HFO-1234yf does not pose an exposure risk due to chemical toxicity
11

Toxicology Comparison HFO-1234yf and R134a

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12

HFO-1234yf Combustion Energy

Flammability is evaluated by ‘Chance of Flame occurring’ and ‘Effect of Flame

occurring’

• Effect of Flame occurring -> Burning Velocity, Heat of Combustion

* Burning Velocity of 1234yf has been measured at AIST. (Advanced Industrial Science and Technology / Japan)

Even if ignited, HFO-1234yf burns only weakly, would have limited effect

0

10

20

30

40

50

60

0 5 10 15 20 25 30 35 40 45 50

Burning Velocity, cm/s

H

e

a

t

o

f

C

o

m

b

u

s

tio

n, M

J

/

k

g

Increasing

Impact

152a

Ammonia

R32

1234yf

R134a

methane

propane butane

ASHRAE Class 3

ASHRAE Class 2

Class 2L

(proposed)
13

HFO-1234yf Flammability Properties

Flammability is evaluated by ‘Chance of Flame occurring’ and ‘Effect of Flame occurring’

• Chance of Flame occurring -> Lower Flame Limit, Minimum Ignition Energy

Difficult to ignite HFO-1234yf due to high Minimum Ignition Energy

0.01

0.1

1

10

100

1000

10000

0 2 4 6 8

Lower Flame Limit, vol.%

Minim

u

m Ig

nitio

n

E

n

erg

y, m

J

152a Methane

Acetylene

Propane

Iso-Butane

Gasoline

Increasing

Flammability

HFO-1234yf

> 5000 times

more energy

to ignite!
14

Pressure Rise on Ignition

t = 63 ms 125 msec 250 msec 500 msec 750 msec

Isobutane

Elect. Arc

4 vol%

R-152a

Elect. Arc

8 vol%

HFO-1234yf

Elect. Arc – no ign

Lighter – above 4 vol%, no ign

Elect. Arc + butane → ign

8 vol%, orange flame is butane

Watch the ping pong balls for pressure rise.

HFO-1234yf Flames can best be characterized as

‘Lazy and Unstable’ with low energy release
15

Sources for Ignition

 Potential ignition sources were evaluated by

INERIS, DuPont, and Honeywell

 Ineris results reported in Phoenix in 2008

 Fiat analysis reported in SAE paper # 2009-0 -0541

 Very few capable of igniting HFO-1234yf

 Only credible sources were considered in the

FTAs, such as:

 Match (butane lighters are not operable above 4 vol%)

 PTC heater failure, un-fused electrical short failure

 Hot surfaces in the engine compartment under

extreme vehicle use

Details of testing in the Project Summary Referenced in the Press Release

Possible ignition sources for HFO-1234yf are limited
16

Ineris Potential Ignition Sources for HFO-1234yf

Ineris testing

found very few

potential ignition

sources within

vehicle.

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Butane Lighter
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Cigarette Smoking Test

There were no significant

differences in the amount of

HF formed during inhalation

of either R-134a or HFO1234yf through a cigarette.

The HF values found during

this investigation were very

low (less than 10 ppm).

[With refrigerant

concentrations up to 2%]

R-134a has been used for

over 16 years within the

automotive industry as a

mobile air-conditioning

refrigerant.

Massachusetts

smoking simulator
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Spark Testing with HFO1234yf

 Well-blended R1234yf/air

mixture

 Known concentration in a

sealed 12-l spherical

flask

 Moisture equivalent to

50% RH at 23C

 9.5 mm diameter copper

electrodes located in the

flask

 Short-circuit of 12-Volt

automotive battery (1020

cranking amps) in the

mixture

HFO-1234yf Ignitability to

Spark from

12-Volt Battery Short Circuit
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Battery Short Testing with

HFO1234yf

 Sparks Generated

 No evidence of HFO1234yf ignition

 Tests for 8.13, 8.5,

and 9.0 vol % in air,

HFO-1234yf

 Concentrations at 20

and 60C

HFO-1234yf Ignitability to Spark

from

12-Volt Battery Short Circuit

NO IGNITION OBSERVED
20

Ignition testing in a vehicle

mock-up with HFO-1234yf

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Simulated battery short

NO IGNITION

of refrigerant

Cigarette lighting at breath

Minor flame extension

NO IGNITION

Lighter at Vent Outlet

Lighter fails to operate

above 4 vol%
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Toxicology of HF

 HF can be generated when Fluoro-carbon

refrigerants decompose

 Exposure limits for emergency exposures [AEGLs]

developed under the National Research Council,

supported by the USEPA

 Agreed upon for use in this setting by an international

group of OEM toxicologists

 Initial warning sign due to strong irritancy

 Irritancy perception starts at 2-3 PPM

 HF AEGL-2*:

 95ppm / 10 minutes

 95ppm also adopted by OEMs for 1 minute exposures [conservative approach]

 34ppm / 30 minutes

*Acute Exposure Guideline Level-2

AEGL-2 is the airborne concentration (expressed as ppm or mg/m3)

of a substance above which it is predicted that the general

population, including susceptible individuals, could experience

irreversible or other serious, long-lasting adverse health effects or

an impaired ability to escape.
22

Thermal Decomposition/HF

Generation below LFL

 All fluorinated refrigerants, when exposed to sufficient

energy sources, can decompose to produce primarily HF

 The amount of HF generated depends on the amount of refrigerant

in contact with energy source and time of contact

 Testing of HF generation conducted with an actual vehicle (Hughes

Associates) and with “bench-top” studies (INERIS, Honeywell,

DuPont)

 Measured HF concentrations were evaluated using NRC

AEGL-2 values

 AEGL-2 limit for HF [95 PPM, 10 minute exposure] applies explicitly

to acute, accidental exposure situations

 AEGL-2 protects against escape impairing or irreversible effects

 Value adopted by the CRP1234 toxicologists for short time

exposures, highly conservative approach

 Irritancy perception (3-5 ppm) is well below the AEGL-2

Extensive testing and evaluation of HF generation potential
23

HF Concentrations Produced by

Thermal Decomposition

 Passenger cabin - HF concentration due to HFO-1234yf

thermal decomposition below the LFL after refrigerant

release and exposure to flame source

 Highest HF breath level concentration achieved was well below

AEGL-2

 Lighter had to be augmented with strong spark to get a butane

flame [no ignition of refrigerant]

 Engine compartment - HF concentration measurements

after HFO-1234yf released onto hot surface

 Highest HF breath level concentration was well below AEGL-2

in passenger cabin, based on....

 Extreme engine operation (700oC)

 Hood seal removed allowing direct path to cabin air intake

 Secondary failure

 Blower on outside air, high speed (full suction from engine)

Estimated occupant HF exposures would not exceed AEGL-2 value
24

Input Service Scenarios

 New CFD modeling was applied to service-related

refrigerant releases

 Service pits are assumed to be covered by existing

confined space regulations and were not considered in

the FTA

 DIYers – Assumed that EPA will require that only

certified professional technicians conduct AC service

 SAE standards will require that AC service be conducted only

by certified professional technicians

CFD modeling of repair scenarios suggests minimal refrigerant ignition hazard
25

Basis of confidence in proposed Vehicle Maker use

conditions

 Risk Analyses

 Conservative assumptions

 Scientifically valid

 Reviewed by industry experts

 Product is acceptable for market without concentration limits

 SAE Standards

 Standards and practices to assure proper system design,

engineering, manufacturing and servicing for HFO-1234yf

refrigerant use in passenger motor vehicles

 Experimental Test Program for Ignition and HF production

 International, independent test laboratories in US, Europe and

Japan

 Addressed EPA concerns in the notice of proposed rule

Vehicle safety will not be compromised

by use of this refrigerant
26

Risk Comparison to Other Vehicle events

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*Data sources are shown on page 36

Risks from Various Events Compared to Risks Associated with Leaks of R-1234yf

Risk Risk per vehicle per

operating hour*

Citation

Risk of being in a police reported vehicle collision1 5 x 10-5 NHTSA, 2007

Risk of vehicle collision due to vehicle brake failure2 3 x 10-7 New York State DMV

Risk of highway vehicle fire (any cause)3 1 x 10-7

Ahrens, 2008; BTS,

2004

Risk of an airbag-related fatality associated with a vehicle collision4

2 x 10-10 NHTSA, 2001

Risk of vehicle occupant/former occupant experiencing HF exposure

above health based limits associated with an R-1234yf ignition event5

3 x 10-12 Current analysis

Risk of vehicle occupant being exposed to an open flame due to R1234yf ignition5

9 x 10-14 Current analysis

Risk Risk per working

hour*

Citation

Non-fatal recordable Injury at work (all occupations)6 2 x 10-5 NSC, 2004

Risk among automotive repair technicians of being struck by object resulting

in lost work days7

2 x 10-6 BLS, 2007

Risk of recordable incident involving repair technicians being struck

with high pressure R-1234yf equipment hose (risk per hour of vehicle

service)5

3 x 10-8 Current analysis

Risk of service technician exposure to an open flame due to R-1234yf

ignition5 1 x 10-20 Current analysis
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CRP1234-2

Material

Compatibility

Summary

In all cases some

combination of

materials is found

acceptable

27

*Green color indicates no issues

were noted, Yellow color

indicates some improvements

are suggested, no color

indicates materials were not

tested.

Table 1a – Overall Project Summary – Material Compatibility and

Permeation*

Material Compatibility Permeation Permeation

Oil A

HFO1234yf

Oil-B

HFO1234yf

Oil-C

R134a

HFO1234yf R134a

Seals

EPDM-1

EPDM-2

EPDM-3

EPDM-4

HNBR-1

HNBR-2

HNBR-3

CR-1

ormal Temp. Hoses

CR-1

CIIR-1

CR-2

CIIR-2

PA-1

PA-2

igh Temp. Hoses

CR-3

CR-4

IIR-1

PA-3

PA-4

PA-5

Thermo-plastics

PPS-1

PPS-2

PEI-1

Table 1b – Overall Project Summary –Oils*

Oil Thermal Stability Miscibility Daniel Plots

R134a HFO1234yfR134a HFO1234yfR134a HFO1234yf

Oil-A

Oil-B

Oil-C

Oil-D

*Green color indicates no issues were noted, Yellow color indicates improvements are suggested, no

color indicates materials were not tested
28

Life Cycle Impact of HFO-1234yf

Air conditioning systems

derive their power to run

from the vehicle’s engine, so

their efficiency impacts the

greenhouse tail pipe

exhaust gas emission of the

vehicle.

Direct emissions:

The greenhouse gas emissions

resulting from the direct emission of

the refrigerant.

Indirect emissions:

The greenhouse gas emissions (CO2)

resulting from the power needed to run

the air conditioning system. The majority

of total GHG emissions come from this,

especially for low GWP fluids.

In developing a low-GWP solution, one must look at the GHG impact of the refrigerant

and its efficiency with an eye on total greenhouse gas emissions

1/27/2010 28

Results are dependent on base system and level of system optimization
29

Atmospheric effects

The following impacts have been considered:

Climate change

Stratospheric ozone

Local air quality

Ecosystems (formation of noxious/toxic

degradation products)

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No significant impacts or concerns exist.
30

Conclusion

The sponsors of the SAE CRP1234 have

concluded that HFO-1234yf can be used

as global replacement refrigerant in

future mobile air conditioning systems

and it can be safely accommodated

through established industry standards

and practices for vehicle design,

engineering, manufacturing, and service.

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