April 20, 2021 | Adam BarowyResearch Engineer, Fire Research & Development

UL 9540A Installation Level Research

Tests - Safety Considerations for

Outdoor Containerized Li-Ion ESS

Copyright 2021 UL Inc. All rights reserved

Energy Storage Systems Safety and Reliability Forum

Agenda

1. Objectives

2. Test Setup

3. Results

4. Key Findings

5. Tactical Considerations

6. Future Test Method R&D

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Objectives - UL 9540A Demonstration Series

1. Develop nonproprietary UL 9540A installation test data with

representative lithium-ion battery products, with and without active fire

protection systems.

2. Develop fire service size-up considerations using typical fire service

hazard evaluation equipment under anticipated li-ion ESS thermal

runaway use conditions.

3

Test Setup - Installation Level Test Configurations

➢ Test 1 – Without any provision for fire protection.

➢ Test 2 – With Novec 1230 total flooding clean agent system (8 v% concentration).

➢ Test 3 – With 0.5 gpm/ft2 density water spray system (from ceiling).

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BMS BMS

4'-11 9/16"

1'-2 1/8"

6'-3 3/4"

7'-8 3/4"

Operation pressure 0.5 psig; vent area calculation based on NFPA 68,

Standard on Explosion Protection by Deflagration Venting

Test Setup – ESS Unit Construction and Spacing

Initiating Unit

Partial Unit

Partial Unit

3.0in.

DoubleDummy

Unit

DoubleDummy

Unit

Single Dummy

Unit

3.0in.

89.85

Side B

Side D

Sid

e A

Side C35.20in.

Dimension Spacing

Aisle 35”

Unit side to wall 0”

Unit rear to wall 3”

Unit to unit 0”

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Test Setup – ESS Unit Construction

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Test Setup - Instrumentation (Elevation View, Long Axis)

Pressure Transducers

Wall Surface Thermocouple

Gas Temperature Thermocouple

Battery Temperature Thermocouple

Vertical Thermocouple Array (in plan view)

Smoke Detector

Smoke Obscuration Meter

Gas Measurement Probe

Hydrogen Gas Detector

LEL Gas Detector

Carbon Monoxide Detector

Heat Flux Gauge

Deflagration vent

Live batteries

Dummy unit area

Expanded metal unit door

BMS BMS

36.00

16in.

16in.

7

Test Results

8

Results - Test 1, Timeline of Major Events

Smoke accumulation

[TR + 00:00:31]

Ignition

[TR + 00:00:31]

Partial volume deflagration

[TR + 00:00:31]TR propagation

for 3 hours

[TR + 00:11:54]

Flaming outside container

[TR + 00:47:18]

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Results - Test 2, Timeline of Major Events

Novec 1230 discharge

[TR + 00:00:58]

Smoke stratification before

ignition [TR + 00:26:51]

Ignition [TR + 00:28:32]

Deflagration

[TR + 00:44:39]

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Flashover and flaming from

open door[TR + 02:09:48]

Results - Test 3, Timeline of Major Events

Ignition, sust. flaming

[TR + 00:08:49]

Waterflow @ 0.5 gpm/ft2

[TR + 00:10:13]

Deflagration

[TR + 00:42:02]

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TR propagation after

water flow off

[TR + 01:13:05]

TR propagation continues

after water flow

restart [TR + 01:49:54]

Key Findings

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Key Findings – Gas Detection

Common combustible gas/hydrogen detectors:

1) Effective for detecting that thermal runaway has occurred.

2) Not reliable for ongoing hazard assessment.

Advantages:

• All detectors responded within seconds when exposed to battery gas.

• Nuisance activation unlikely given measurands (e.g., H2, CO, LEL).

Limitations:

• Detection time dependent on positioning. Positional dependency was not within test scope.

• Cross sensitivity diminishes electrochemical sensor accuracy

• Catalytic bead:

• Imprecise measurements of flammable gas mixtures,

• Requires > 10% O2 for proper operation,

• “Poisoned” by halogen exposure.

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Key Findings – Novec 1230 Total Flooding System

When simulating a total flooding system approach, Novec 1230 did not deliver sufficient cooling to

prevent propagation of thermal runaway or to prevent thermal exposure to combustible construction

materials.

Rear Wall – No Novec 1230 Rear Wall – w/ Novec 1230

Firefighting

period

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Key Findings – Water Spray Suppression System

Ceiling-based water spray suppression system prevented unit-to-unit propagation, cooled surfaces

adjacent to initiating ESS unit. Limited effectiveness to prevent module-to-module thermal runaway

propagation within initiating unit.

Rear Wall – No Water Rear Wall – w/ Water

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Key Findings – Deflagration Protection System

The generation and accumulation of battery gases created an explosion hazard and was mitigated

with an engineered deflagration protection system.

Test 1 - Baseline Test 2 – Novec 1230 Test 3 – 0.5 gpm/ft2

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Key Findings – Comparison to Room and Content Fires

Propagating thermal runaway events generate more severe flammability and toxicity hazards than

typical room and content fires.

• THC: ~3 v%

• H2: > 10 v%

• CO: 12 v% - 15 v%

• CO2: ~10%

• H2 = 0 v%

• CO: ~6 v%

• CO2: ~10%

Gottuk, D, Beyler, C., Roby, R., Peatross, M., “Carbon Monoxide

Production in Compartment Fires”, J. of Fire Prot Eng. 4, 4, 1992

Tactical Considerations

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Tactical Consideration – Ventilation

Ventilation of an ESS installation may result in a deflagration or rapid transition to flashover.

∆t = 21 s ∆t ≈ 3 min

UL Tests - Flashover Surprise, AZ – Deflagration*

*M. B. McKinnon, S. DeCrane and S. Kerber, "Four Firefighters Injured In Lithium-Ion Battery Energy

Storage System Explosion - Arizona," UL Firefighter Safety Research Institute, Columbia, MD, 2020.

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Tactical Considerations

• Using portable gas meters to evaluate interior conditions or the gases/vapors leaking from an ESS places firefighters in an explosion hazard area.

• Portable gas meter measurement of battery gas is likely to be compromised by clogging and cross-sensitivity to battery gas mixture species.

• A deflagration event is hard to predict, even with good quality gas concentration data.

• Responding firefighters should consider using portable gas meters and visual observations to define an exclusion zone, while wearing full structural PPE (Level D Ensemble) with full SCBA.

• Additional tactical considerations and detail available in the full report:

https://ulfirefightersafety.org/research-projects/firefighter-line-of-duty-injuries-and-near-misses.html

Future Needs:

1. Better understanding and ID of ESS deflagration precursors are needed for incident

size-up.

2. Responding firefighters need access to ESS instrumentation data, particularly gas

measurement, through a remote monitoring panel and to personnel who can aid in

interpretation.

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Enclosure Explosion Safety Test Method Development

• Test methodology, performance criteria needed to

evaluate safety performance of ESS enclosures

designed to contain deflagration pressures or

control deflagration pressure relief.

• Deflagration venting systems cannot be

evaluated unless a deflagration occurs during

test.

• Deflagration severity during a UL 9540A test is

dependent on gas conditions at the time of

ignition.

• Evaluation ESS product explosion hazards

should not be conducted by unqualified persons.

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Enclosure Explosion Safety Test Method Development

Methodology under development to evaluate explosion hazards:

➢ Blast waves and projectiles ➢ Direction of energy release➢ ESS enclosure rupture

Thank you for your time. Questions?

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Adam Barowy

Adam.Barowy@ul.com