detector test standard Raman Chagger Principal Consultant, Fire - - PowerPoint PPT Presentation

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Research supporting the development of a video fire detector test standard

Raman Chagger Principal Consultant, Fire Safety Group, BRE FIREX, 20th June 2018

Background

• Video fire detectors use cameras to monitor a space and

analyse signals to detect the presence of smoke or flame.

• Complex algorithms and very different methods to identify

the smoke or flame signature of a fire.

• Currently no European standard for this technology.
• BS 5839-1:2017 states video fire detectors :
• … Video fire detectors can also be used as a means of

verifying a fire. Where they are the sole means of detection, they need to be designed, and their suitability and performance verified, by a qualified specialist.

• … performance of video fire detectors and reliance is

placed on manufacturers’ recommendations.

• … tend to be used as supplemental detection or for special
• applications where other detection techniques are

inappropriate or ineffective.

• No plans for standard development at CEN level

Background – VFD work

• In 2012 the Fire Industry Association (FIA) formed

the Video Fire Detectors task group

• Aim was to support the development of the ISO

7240-29 test standard

• Need to develop for Video Flame Detectors (VFD)

and Video Smoke Detectors (VSD):

• benchmark tests
• perational performance tests
• March 2014 a Video Fire Detector FIA/BRE

research group

• All known VSD and VFD manufacturers were

approached with requested to contribute to the research A D Holdings

Aims of the research group

To develop:

• reproducibility measurement

methodology for

• VFD
• VSD
• Operational performance

methodology for

• VFD
• VSD

Phase 1 Phase 2

• Limited to flames in the visible spectrum
• Where possible to use EN 54 test methods
• Existing standards were reviewed but did not provide

sufficient guidance on how to perform these tests

Video Flame Detection- bench tests

Modified EN 54-10 bench test methodology was used Two systems were tested and would not respond to the same test method. The following were developed: 1) a looped video of flaming Bunsen burner 2) a constant un-flickering flame

Video Flame Detection- bench test results

System 1 (steady flame) - Reproducibility Specimen No. Response point (mm) Dmax & Dmin Ratio 1 Dmax : Dmean Ratio 2 Dmean : Dmin 1 2050 1.11 1.16 2 2200 Dmax 3 2100 4 1700 Dmin 5 2100 6 1700

Requirements of EN 54-10:2002: Dmax : Dmean  1.15, Dmean : Dmin  1.22

System 2 (flame video) - Reproducibility Specimen No. Response point (mm) Dmax & Dmin Ratio 1 Dmax : Dmean Ratio 2 Dmean : Dmin 1 2500 1.09 1.06 2 2300 3 2200 Dmin 4 2550 Dmax 5 2250 6 2250 7 2250 8 2400

Requirements of EN 54-10:2002: Dmax : Dmean  1.15, Dmean : Dmin  1.22

☺ 1_4

Video Smoke Detection- bench tests

The metric root mean squared error (RMSE) deviation was identified that enabled smoke change to be “measured” One pixel of four from white to black RMSE = 25% All four pixels from white to 10% black RMSE = 10% Thousand of pixels RMSE ~0.02%

Video Smoke Detection- bench tests

• EN 54-7 fire tests were used to produce

a video of smoke growth

• External conditions fully controlled
• Video of the fire was played back on a

monitor display at a fixed distance from the camera.

Video Smoke Detection- bench test results

System 1- Reproducibility Specimen No. Response time (min:sec) RMSE (%) RMSE Max/Min Max:Mean Mean:Min 1 6:36 0.0278 1.045 1.031 2 6:40 0.0284 3 6:36 0.0278 4 6:31 0.0271 5 6:44 0.0292 MIN 6 6:34 0.0275 MAX

Requirements of EN 54-7:2001: Max:Mean ≤ 1.33 and Mean:Min ≤ 1.5

System 2- Reproducibility Specimen No. Response time (min:sec) RMSE (%) RMSE Max/ Min Max:Mean Mean:Min 1 7:46 0.0439 MIN 1.070 1.019 2 7:46 0.0439 3 7:50 0.0440 4 7:46 0.0439 5 7:46 0.0439 6 7:59 0.0479 MAX

Requirements of EN 54-7:2001: Max:Mean ≤ 1.33 and Mean:Min ≤ 1.5

☺ 2_4

Video Flame Detection- performance tests

EN 54-10 fire test methodology was used as a basis

• 2 test fires (n-heptane and methylated

spirits) performed in trays at distances up to 100m

• Time of response measured from start of

fire

Video Flame Detection- performance tests results

10 20 30 40 50 60 70 80 90 100 20 40 60 80 100

Time to response (sec) Separation distance between VFDs and fire (m)

N-heptane Day 1 VFD 1 Methylated spirits Day 1 VFD 1 N-heptane Day 2 VFD 1 Methylated spirits Day 2 VFD 1 Upper limit Lower limit

• Point-type flame detectors are required to alarm within 30

seconds of exposure to the fire.

• Appears to be a repeatable response up to 30m.
• Proposed to use methodology and requirements of EN 54-10
• 8 samples are tested at claimed maximum distance to respond

before 30 seconds for both test fires.

☺ 3_4

Video Smoke Detection- performance tests (Trial 1)

To use “Illuminated smoke” in a dark ambient environment Aim to:

• Control the ambient environment
• Produce smoke only with a background to contrast against
• VSDs saturated by the light
• Ambient levels too low

Video Smoke Detection- performance tests (Trial 2)

• To perform “in principle” tests at the BRE fire test room
• Used black and white tarpaulin screens to contrast the smoke from

the fire

• TF2 to TF5 from EN 54-7 were performed with reduced fuel loads
• Videos cropped and analysed using the BRE VSD analysis tool.

Video Smoke Detection- performance tests (Trial 2)

• RMSE growth profiles observed for the 4 test fires
• Identified that light from the fire reflected on the tarpaulin screen

contributed to the RMSE analysis for the TF4 and TF5 fires

• Identified that illumination of the screen would have to be indirect

Video Smoke Detection- performance tests (Trial 3)

• To perform tests on full scale at BRE Middlesbrough (at night!)
• Remove direct flames and reflections from screen

Video Smoke Detection- performance tests (Trial 3)

• Reflected light observed on the tarpaulin screens from the fire
• Direct light from the fire

Video Smoke Detection- performance tests (Trial 4)

• Use of “chimney cap” to prevent direct or indirect light from flames

Video Smoke Detection- performance tests (Trial 4)

Video Smoke Detection- performance tests (Phase 4)

Whilst not obvious to the human eye the tarpaulin screen was moving due to air movement in the space…

0.000 0.005 0.010 0.015 0.020 0.025 0.030 20 40 60 80 100 120 140 160 180 200

RMSE (%) Time (sec)

Original data 10 second average

Video Smoke Detection- performance tests (Phase 4)

Smouldering fires on white Flaming fires on black

Smouldering fires- lacked repeatability Flaming fires- TF4 fire much more repeatable.

Video Smoke Detection- performance tests

• The sets of fire tests demonstrate, in principle, the viability of the

test method.

• Succeeded in:
• Illuminating the screen without producing large reflections
• Removing light from the fire from reaching VSDs
• Removed reflections on the screen
• Illuminating the smoke
• VSDs responded to the smoke from the fires
• Hurdles:
• Need to develop a means for producing a stable background
• Need to demonstrate repeatable RMSE profiles for TF2-5 fires

More work required…

4_4 X

Video Smoke Detection- Phase 3

• Extension of research (additional phase 3)
• Completed 15 June 2018
• Utilised a fixed installation of plasterboard

sheets that was:

• Painted white for flaming fires (4xTF4

and 4xTF5 fires)

• Painted black for smouldering fires

(4xTF2 and 4xTF3 fires)

• Results from the fires are currently being

analysed.

Conclusion

• Research has successfully achieved

test methods that can be utilised in a video fire test standard.

• Benefits of collaboration
• BRE and the FIA are now pursuing

the development of a Loss Prevention standard and associated CoP.

• Briefing paper is currently being

prepared (Sept/Oct 2018).

• Interested in further information?

https://www.bre.co.uk/preference- centre/register.jsp https://www.fia.uk.com/newslettersubscr iption.html

Thanks A D Holdings