2.3

Overview of the Risk Assessmentfor VRF System

JRAIA, VRF Risk Assessment SWG
Leader: Ryuzaburo Yajima

Members : Yukio Kiguchi, Sekine Takashi, Shunji Sasaki , Shuntaro Ito,Koji Yamashita, Tatsumi Kannon, Masahiro Honda,
Masahito Yoshizawa, Hiroichi Yamaguchi, Tetsushi Kishitani,
Takahiro Matsunaga

The 24th IIR International Congress of Refrigeration
August 20, 2015, Yokohama, Japan

CONTENTS
 Features for VRF with mildly flammable refrigerants
 Targets and schedule 1st step

Establishment of method for risk assessments

 2nd step

Risk assessment results and proposal of safetymeasures 3rd step

Proposal of technical standards which canachieve both of safety and environments*) R32 among mildly flammable refrigerants is investigated in this risk assessments.
© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

1

Features of VRF systems and A2L refrigerants
Features of VRF system compared with single split

Risk Large amount of refrigerant charge that can all leak into just one room
 Numerous joints connecting refrigerant circuit or parts of valves,vessels and sensorsup Strict check of refrigerant sealing and leaks
 Highly skilled personnel for installation, repair and maintenance

A variety of system configuration, mode free type,water cooled or ice storage type, etc.

 Wide range capacity of outdoor and indoor units

down
Risk should bespecified＋Features of A2L refrigerants compared with A2, A3

Risk

 Lower size of flammable space because of larger LFL
 Type of ignition source is limited because of larger MIE

down＝Risk is allowable ? Safety measures ?
© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

LFL : Lower Flammable Limit
MIE : Minimum Ignition Energy
2

CONTENTS
 Features for VRF with mildly flammable refrigerants
 Targets and schedule 1st step

Establishment of method for risk assessments

 2nd step

Risk assessment results and proposal of safetymeasures

 3rd step

Proposal of technical standards which canachieve both of safety and environments*) R32 among mildly flammable refrigerants is investigated in this risk assessments.
© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

3

ObjectivesStepObjectives

Schedule

1st・Establishment of method for riskassessments’11/4 ～’12/7

2nd・Proposal of safety measures based on
the assessment results’12/8 ～’14/9

3rd・Proposal of technical standards which canachieve both of safety and environments’14/10 ～’16/3

Harmonization

Safety(regulations)

Environments(commercialization)© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

4CONTENTS
 Features for VRF with mildly flammable refrigerants
 Targets and schedule 1st step

Establishment of method for risk assessments

 2nd stepRisk assessment results and proposal of safetymeasures

 3rd step

Proposal of technical standards which canachieve both of safety and environments*) R32 among mildly flammable refrigerants is investigated in this risk assessments.
© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

5

Probability of fire accidents
PAccident = PLeak × PSpace_enc. × PTime_enc.
PAccident : Probability of fire accident[times/(unit・year)]
PLeak: Probability of rapid gas leakage[times/(unit・year)]
PSpace_Enc. : Probability in space of encounters of ignition sources and flammable cloud[-]PTime_Enc : Probability in time of encounters of ignition sources and flammable cloud[-]

Number of stockin market

Fire accident
PAccident

Rapid gas leakage（propability=1）

PLeak

Encounters of ignition
sources and flammablecloud in space
PSpace_enc© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

Encounters of ignition
sources and flammablecloud in time
PTime_enc6

Probabilities of gas leaks
Probability of gas leaks classified by leak rates
Slow Leak Rapid Leak Burst Leak～1 [kg/h] ～10 [kg/h] ～75 [kg/h]
3503455076006126
1338137

Total
Indoor Unit
Outdoor Unit

Probability of Leak [ppm]Probability of Leak [ppm]Measurements of leak rate

Servicing data of manufacturer B, 2010

Leak Rate [kg/h]

1.0E+01
1.0E+00
1.0E-01

Investigation of numbers of rapid leak; Emergency Servicing based on
Declaration from Customer,e.g., White Smoke.
Liquid Leak Rate (63℃)
Gas Leak Rate (10℃)

Indoor Unit
Outdoor UnitWhiteSmoke01

SmelledBurning
13

Holesin Pipe03Nrp
171.0E-02
1.0E-03
1.0E-04© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

7

Ignition Sources
Y：Ignited

Spark(in flammablecloud)

Open
Flame
(contact withflammablecloud)N：not ignited

Ignition Source

R32

R290

Electric Parts

Appliance（cause of fire）
Parts in Unit
Power Outlet, 100V
Light Switch

Y
NN
N

Y
YYY

Smoking
Equipment

Match
Oil Lighter
Electric Gas LighterYY : being evaluatedNY
YY

Work Tool

Metal Spark (ｆorklift)
Electric Tool
Recovery Machine

YNNY
YY

Body

Static Electricity

NY

Smoking
Equipment

MatchOil or Gas LighterYYY
Y

Combustion
Equipment

Heater
Water Heater
BoilerCooker

YYYYYYYYWork Tool

Gas BurnerYY© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

(ref.)

8

CONTENTS
 Features for VRF with mildly flammable refrigerants
 Targets and schedule 1st step

Establishment of method for risk assessments

 2nd step

Risk assessment results and proposal of safetymeasures 3rd step

Proposal of technical standards which canachieve both of safety and environments*) R32 among mildly flammable refrigerants is investigated in this risk assessments.
© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

9Models of indoor installations
1) Meeting room in office (Ceiling cassette type)3) Karaoke (Ceiling cassette type )Combustion
Cameraカメラ
Heater(燃焼式暖房機)
2200
Outlet2200
コンセント

Intercom
Fan(扇風機) インターホンVent
Opening
換気口

Table
テーブル

テレビ
TV

26.3 to 88.1

V [m3]

110

Karaoke Set
カラオケ機器

1800
1800

R32[kg]

換気口

R32[kg]88.1

V [m3]

9.5

空気清浄機

AirPurifier

加湿器

HumidifierFig. 8.2.4.9 Model of karaoke

2) Restaurant (Floor type)4) Ceiling space (Ceiling duct type)

R32 [kg]
V[m3]

52.8

R32 [kg]

88.1

24.3

[m3]

32.5

© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

V10

Probability of fire accident during indoor operation
In each installation cases

Allowable

Fire accident probability A

Installation caseWithout measures
No vent.

Vented *1)

Withmeasures

3.8*10-1

7.6*10-9* 2)

3.5*10-12

3.5*10-12

Ceiling

2.1*10-3

1.8*10-7

4.4*10-11

0.0

Floored2.0*10-2

3.8*10-7

5.4*10-9 *3)

2.6*10-10 *4)

1.3*10-9

1.2*10-10

6.8*10-12

TypeConstituent
ratio POfficeCeiling

Karaoke
Restaurant

Site

Not allowable[time/(unit・year)]

IndoorAllowable
probability

1.0*10-9

Hair salon

Ceiling

1.6*10-3

BBQ
restaurant

Ceiling

7.8*10-4

2.8*10-9

4.4*10-10

1.5*10-11

Ceiling SpaceIn officeDuct3.8*10-1

3.0*10-10--

1.1*10-8

1.1*10-10

6.6*10-12

Total in market
Total＝Σ(P＊A)

4.0*10-1

1.0*10-9*1) Indoor ventilation according to Japanese building code*2) Ventilation turned off 18:00 to 09:00*3) Supply and exhaust on the ceiling surface*4) Mechanical ventilation with a vent opening near the floor© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

11

FTA of Indoor Operation (Office, ventilation turns off at night)© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

12

Indoor safety measures by refrigerant charge ratio
Step 1

Calculation of R, refrigerant charge ratio
R [kg/m3] ＝Step 2

R : Refrigerant charge ratio [kg/m3]
M : Total charge amount [kg]V : Room volume [m3]M [kg]
V [m3]= Floor Area [m2] * Ceiling height [m] R values and number of measure
are under consideration

Safety measurements corresponding to R

R [kg/m3]
QLUV
Ventilation
through gap

NoVentilation

Except ones on the lowest floor
The lowest underground floor *)Step 3

QLMV

None
None

1

Select safety measures among the following

QLAV
Additionalventilation

One more measure

122

System redesigned*) No effect of ventilation through gap

1. Leak detection + Ventilation（interlocked with indoor unit）
2. Leak detection + Refrigerant shut off valve（ interlocked with indoor unit if the valve is not placed in indoor unit )3. Leak detection + Warning alarm（ interlocked with indoor unit if the alarm is not placed in indoor unit )© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

13

Outdoor Installation Models
a. Typicalb. Each floor
5%94%

GroundGroundc. Machinery room
0.6%

d. Semi-underground

GroundLouver0.01%
GroundMachineryRoom・Charge amount : 26.3～max. 150kg

Constituent ratios© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

14

Probability of fire accident during outdoor operation
In each installation cases[time/(unit・year)]

SiteOutdoor

Allowable

Fire accident probability A

Installation case
Constituent
ratio P

Not allowable

Without measures
Allowable
probability

No vent

Vented *1)

Withmeasures

Open space

9.4*10-1

1.9*10-11--

Each floor

5.0*10-2

3.0*10-9--

Semiunderground1.0*10-4

1.1*10-7-

2.5*10-13

Machineryroom

6.0*10-3

6.1*10-8-

3.2*10-9

5.4*10-10-

1.9*10-114.0*10-9Total in market

Total＝Σ(P＊A)

1.0

4.0*10-9*1) Indoor ventilation according to Japanese building code

© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

15

Safety measures for semi-undergroundNo ventilation
Flammable regionh0

Safety measures are necessary under the following

Ventilated（suction duct）

M : Charge amount
V: Volume of semi-underground space
LFL : Lower flammable limit
h0 : Depth of semi-underground space

[kg]
[m3]
[kg/m3][m]

Select safety measure from the following
1. Installation of suction duct and leak detector
2. Ventilation with outdoor fan after detectionof gas leak© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

16

Safety measures for machinery room
Continuous mechanical ventilation, 2 times/h * 2 series（Volume ≥ 95m3, Height ≥ 5m）

Air inlet

Air outlet

Probability of fire accident andventilation rate
Probability of fire accident

Installation case

Allowable line

Ventilation rate [times/h]・Size 3.3*6.6*5.0m = 109m3（size change evaluated）
・Leak rate = 75[kg/h], Charge amount = 150[kg]・Failure rate = 0.025 [%/series] * 2 [series]

・Boiler and smoking tools asignition sources© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

17

Probability of fire accident during each working
In each installation cases

Not allowable[time/(unit・year)]

Allowable

Fire accident probability A

Installation caseInstallation
Constituent ratio P

IndoorOutdoorAllowable
probability

Repairing

DisposalWithoutmeas.

Withmeas.

Withoutmeas.

Withmeas.

Withoutmeas.

Withmeas.

OfficeCeiling

3.8*10-1

1.9*10-9-

8.7*10-11

8.8*10-122.9*10-14

2.9*10-15

Restaurant

Floored2.0*10-2

1.9*10-9-

1.2*10-8

3.9*10-11

3.4*10-12

3.4*10-13

KaraokeCeiling

2.1*10-3---－-－

Open space-

9.4*10-1

1.9*10-9-

1.4*10-9

1.4*10-10

2.4*10-10

3.2*10-11

Each floor-

5.0*10-2

1.9*10-9-

3.1*10-9

3.1*10-9

1.0*10-9

1.4*10-10

Semiunderground-1.0*10-4

1.1*10-8

1.9*10-9

3.6*10-7

2.1*10-9

3.3*10-8

4.8*10-10

Machineryroom-

6.0*10-3

1.1*10-8

2.1*10-9

8.6*10-7

5.4*10-9

2.2*10-8

3.3*10-10

1.0*10-8

Total in market
Without meas.

With meas.

Indoor total＝Σ(P＊A)

4.0*10-1

1.0*10-8

1.0*10-9

4.1*10-12

Outdoor total＝Σ(P＊A)

1.0

1.0*10-8

9.0*10-9

3.7*10-10© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

18

Safety aspects for service personnel

1. Leak check where gas to be accumulated easily
2. How to avoid harm of ignition of gas-burner
3. Education for service people about A2L refrigerants4. Description of cautions on service manuals© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

19

CONTENTS
 Features for VRF with mildly flammable refrigerants
 Targets and schedule 1st step

Establishment of method for risk assessments

 2nd step

Risk assessment results and proposal of safetymeasures 3rd step

Proposal of technical standards which canachieve both of safety and environments*) R32 among mildly flammable refrigerants is investigated in this risk assessments.
© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

20Impact on Fire accident probability
Strength of flammability and charge amount have large impact
ProductRef.

Chargein dropin*1)[kg]

Site・Vent.

Risk reduction

Withoutmeasure Allowable; with measure

Office

VRF *2)（40.3m2）

R32

88.1

(107 units)

R290*4)0.5・

Turn offat night

Reduced in 10-1

dittoRoomair-con. *3)

Reduced in 10-6

(108units)

Room
R32

1.0（7m2）
・None*1) Drop-in to R410A model
R32 : 10[kg/h], R290 : 7.5[kg/h]*2) Ceiling mounted*3) Wall mounted, single*4) Yao et al, 2000, JRAIA Kobe Symposium.
Leak rate of R290 is same as R32.

flammable
space occurs

10 010-2

encountered with ignition source

10-4

10-6

higher risk

-10-8-10-10

10-12

10-14

lower risk

Fire accident probability [time/(year∙unit)]© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

21

Features of regulations and standards
Appropriate regulations and standards balanced to strength of risks

Products

VRF *2)

Flamma-bility

Charge indrop-in*1)
[kg]

Risk
reduction ratenecessary forsafety

Standard andRegulation forsafety
Industry standards

R32

mild

88.1

10-1

R290*4)strong0.5

10-6

Legal regulations ?

R32

mild

1.0-Voluntary
installation manual

Room aircon.*3)（semi-official facilitystandards are desirable)*1) Drop-in to R410A model, R32 : 10[kg/h], R290 : 7.5[kg/h]*2) Ceiling mounted*3) Wall mounted, single*4) Yao et al, 2000, JRAIA Kobe Symposium., Leak rate of R290 is same as R32.

© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

22Summary
1. Risk assessment is performed for VRF with R32,
probability of fire accidents are clarified.
2. Safety measurements are proposed which canreduce fire risks lower than allowable level, evenunder severe installation cases for VRF with R32.
3. Safety for VRF with R32 should be guaranteedwith industry standard and semi-official facility
standard (ex. KHK standards for facility).
*) KHK : High Pressure Gas Safety Inst. of Japan© 2015 JRAIA The Japan Refrigeration and Air Conditioning Industry Association. All Rights Reserved.

23

Thank you for your attention.

24