Basic Procedure of Risk Assessment
Working Group for Risk Assessment of Lower Flammability Refrigerant

Conclusion

Organization for Risk Assessment
Cooperation among Industry, Government and Academy
Lower-flammablerefrigerants risk project（JSRAE)

JRAIA

Refrigeration and AC
Industry Association

Ministry of Economy , Trade and Industry[Aim]
1. Acquire base data

JAMA

Automobile Manufacturers
Industry Association

METI

1. The charge amount of refrigerant is small
hardly to generate a flammable region.
2. Moderate ventilation can avoid a generationof a flammable region.

NEDO

New Energy and Industrial TechnologyDevelopment Organization厨房compared to LFL
Usually, charge amount is small

OfficeRestaurant(flammability, ignition, gravity of the accident)

2. Review of risk assessment
3. Issue of the report
AIST

National Institute of advanced
industrial science and technology

JSRAE

Japan Society of Refrigerating andAir conditioning Engineers

Academic sector

Smallest
Karaoke
Room
Room Size：169m2
A/C Capacity : 30kW
Charge amount :19kg
Charge of LFL：140kg

Tokyo Univ.
Kyushu Univ.
Tokyo Univ. ofScience, Suwa

Room Size：14m2
A/C Capacity : 30kW
Charge amount :4kg
Charge of LFL：11kg

Dangerous case

: It should be avoided.
1. Most dangerous is the case when theThis is a case when 88Kg leaked refrigerant would be ignited
after it is filled in the room withof refrigerant leaked tothe room with moderate stoichiometric concentration.
ventilation where LFL
limit is 33Kg.

No
FlammableRegion

Set life cycle and tolerable level

Estimate the risk by[1] Leakage probability X[2] Probability of generating a
flammable region X[3] Probability of ignition source
Tolerable？
Validation and documentation

Set Tolerable Level in Risk Matrix for Residential AC

Repair/ServiceUsage

Identify user, intended use, foreseen misuse.
Set the tolerance level of the risk

Storage

STARTTransportation

Life cycle range for assessment
Production

Based on ISO/IEC guide 51

RiskReduction

Room Size：10m2
A/C Capacity : 4kW
Charge amount :1.2kg
Charge of LFL：8kg: This case requires a leakdetector and some safety measure suchas air-circulation, ventilation or shut-offvalve.
1. A case where the leaked refrigerant
can not be circulated, such as a floor
mounted unit etc.
2. A case where the charge amount ofrefrigerant is large compared for theroom size enough to generate aflammable region without moderate
ventilation.

Moderate ventilation can avoid
the generation of Flammable region

JRAIA has been carrying out Risk Assessment from 2011 to 2016

Basic Procedure

Risk case:This case is safe

DisposalIndustry

Government

Normal case

Set Tolerable Probability for each system
Product/
SystemNo. ofunits inmarket

Tolerable Tolerable
value in value except
usefor in use

Residential A/C

1.0×108

1.0×10-10 1.0×10-9

Commercial A/C

6

7.8×107-9

1.3×10-9

1.0×10-8

1.3×10-8

VRF

1.0×10

1.0×10Chiller

1.34×105 7.5×10-7 7.5×10-7

JRAIA decided the tolerable level is less than
one accident in one hundred years. We supposea Ignition would always cause lethal damage
since we could not classify the severity of harmat present. It means JRAIA set the tolerable level
sever at present.

Estimate the Risk :calculate by the formula ” Ignition Probability= [1]×[2]×[3] ”[1] Estimate of the rapid leakage probability

AC type
Rapid Leak Rate
Probability of leak

Residential
15kg/h
0.023％

Package
VRF
10kg/h
10kg/h0.0015% 0.0005%,Chiller
burst 75kg/h
burst 0.0010%

 Assumed a rapid leak rate and the probability of leak for indoor units
based on market data and IEC60335-2-40[2] Estimate of the probability of generating a flammable region
 Assumed a normal condition and a risk case: considering charge
Stoveamount of refrigerant, room size , ventilation, floor mounted type etc.
Probability of occurrence ofGenerated flammable volume-time integration＝──────────────────────────────── Probability of existence of flammable region : calculated by the right
flammable region
Space-volume x Total timeside formula. Generated flammable volume-time integration isdetermined by CFD simulation.
[3] Probability of the ignition source Probability of ignition sources: estimated from statistic data of gas fire accidents.
 Evaluation of ignition sources : NEDO project carried out the variety of ignition tests and researches as bellow;
Research of Contactor

Ignition Test by Stove

Ignition Test by Lighter

Hair Dryer Ignition Test2L

Flame canpropagate throughAir Conditioner
Current Statein Japan
Length between contact point and cover(mm)Electro Contactor can’t beignition source for R32

Flame propagation didn’t
occur by various type of stoves

Gas lighter can’t ignite 2L gas

2L gas were not ignited

Documentation
1.Safety Guideline(GL-20) related to High Pressure Gas Safety Act

Basic policy of the safety guideline is to avoid flammable region. Therefore, it strictly limits
the charge amount of refrigerant to less than or equal to ¼ of LFL. When more than it, adetector-alarmand some safety measures are required.
Documentation

2.Guidelines or manuals for each applications

JRAIA is providing precise guidelines or manuals for each application.

3.JSRAE published the final report for risk assessment

The final report for the risk assessment will be published near soon by JSRAE.

LawHighPressureGas SafetyAct

Guide Line
Guideline
GL-20

GL for each application
Manual for Small sprit A/C
Guideline for Commercial A/C
Guideline for Industrial A/C
Guideline for Refrigeration
Standard for Leak Detector
Guideline for Chiller