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Tracking toxic gases penetration through firefighter's garment

Ge Li , Vesselin Shanov, Mark J. Schulz,

University of Cincinnati

Andrew Schwartz, LION Apparel Inc.

William Jetter, Sycamore Township Fire Department

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Outline

• Background and Objectives

• Our Approaches

• Results and Discussions

• Conclusion

• Future Work

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Background• Firefighters are exposed to chemicals and by-products of

combustion

• The fire environment becomes more risky due to new technology, i.e. chemicals used in hybrid automobiles and furniture

• Fatal injuries reported is increasing annually

• The toxic threats: CO, HCN, HCl, H2S, etc induces sensory irritation of eyes and bronchial irritation and heart attack

• Garment is critical for protection

• Frequent exposure of the garment causes deterioration

• Absorbed chemicals in garment act as a secondary source of hazardous exposure

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BackgroundTypical Firefighter GarmentTypical Firefighter Garment

Outer Shell LayerResist ignition & protect internal layers from rips, tear, abrasion, etc

Moisture Barrier Layer

Preventing external water from penetrating into garment

Air Layers and Thermal Barrier LayerCreate insulation by air spaces within the layer & bring comfort and mobility

Moisture Barrier Layer

Provide the seam strength to hold the whole garment together; ‘wick’ perspiration off the body and bring comfort

Complete system of

four components

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Possible Damages to Fabrics During Fire Event:

• Thermal DamagesThermal Damages (Crease, Shrink, Deform or partly Melt)(Crease, Shrink, Deform or partly Melt)

• Chemical DamagesChemical Damages (Decompose, Dissolve in Acid)(Decompose, Dissolve in Acid)

• Mechanical DamageMechanical Damage

(Graying(Graying, Worn out))

Background

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Objectives

• Study representative samples and analysis the types and quantity of absorbed chemicals

• Create a profile showing how these toxic gases penetration through firefighter’s garment

• Generate data and provide information about durability of fabric

• Find out the possible mechanism of deterioration caused by absorbed chemicals

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Outline

• Background and Objectives

• Our Approaches

• Results and Discussions

• Conclusion

• Future Work

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Sample Collects Sample Set 1: Blank (never exposed to fire)

New garment fabrics (4 layers)

Received from Lion Apparel Inc.

Sample Set 2: Used (exposed in fire-ground for 18+ hours, not washed)

6x3 inch garment coupon (only outer shell layer)

Received from Sycamore Fire Department

Sample Set 3: Retired (Used for 5 years, washed quarterly)

Old Piece of clothing cut from retired firefighter’s garment

(4 layers)

Received from Sycamore Fire Department

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GC/MS (Identify fractures of different substances within a sample)

XRF (Analyze concentration of Chlorine as well as others)

IGA (Analyze C,H,O,N,S in volatile form under high T)

ESEM & EDSESEM & EDS (Micro-Morphology study)

Tensile TestingTensile Testing (Mechanical properties testing)

TGATGA (Thermal properties analysis)

EAG Lab

UC

Methods

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Outline

• Background and Objectives

• Our Approaches

• Results and Discussions

• Conclusion

• Future Work

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ESEM & EDS

Energy dispersive X-ray spectroscopy (EDS)Energy dispersive X-ray spectroscopy (EDS) is an analytical technique used predominantly for the elemental analysis or chemical characterization of a specimen.

Environmental Scanning Electron Environmental Scanning Electron MicroscopeMicroscope (XL30-FEG ) is a microscope with 2 nm ultimate resolution. The Peltier stage may be utilized to keep samples at 100% Relative humidity while they are being imaged.

Fabric appearance is one of the most important aspects of fabric quality

Micro-structures on fabric surface

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Outer Shell Layer (New)Outer Shell Layer (New) Outer Shell Layer Outer Shell Layer (Retired/old)(Retired/old)

Element Wt% At%

CK 70.39 84.15

OK 14.12 12.67

ZnL 00.76 00.17

MgK 00.27 00.16

AlK 00.49 00.26

SiK 00.77 00.40

AuM 06.14 00.45

SK 01.70 00.76

PdL 04.17 00.56

CaK 01.19 00.43

Matrix Correction ZAF

EDSForeign particle

composition

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ESEM (Thermal Barrier Layer)

New Old

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ESEM (Face Cloth Layer)

New Old

No significant difference between new and old face cloth layerNo significant difference between new and old face cloth layer

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ESEM & EDS (Summary)

At outer shell layer, foreign particles were attached on to the fibers; we also found peel-offs and split like (more voluminous and hairy) on the surface of used fibers

The chemical composition of foreign particle contains S, Zn, Ca, Mg

Peel-offs and hairy structure could also be found on old thermal barrier layers

No significant differences of face cloth

Note: Si and O is always there because of the environment inside ESEM. We coated the sample with Au (Gold) in order to get the sample conductive and get good ESEM images.

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Tensile Test Fundamental type of mechanical test

Showing how it reacted to the forces being applied

Equipment: INSTRON 4206

ASTM Standard TestLoad Speed: 0.25inch/min;

Spec. Gauge Length: 1.495 inch; Holding Width: 0.52inch

Sample Size: 6 x 3 x 0.02 inch

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Tensile Test

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Tensile Test

Sample 1 show more elongation, more resilient and higher dead load (17.8%) than sample 2, that means more flexible, softer and stronger

Sample 2 (old) is rigid and brittle.

The reason for this might be the damage of fiber structure while the garment had been exposed to fire event.

High temperature, heavy gas and foreign particles deposited onto the garment surface may cause the deformation or decomposition of the fiber

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TGA

Thermo-gravimetric Analysis (TGA) is a type of testing that is performed on samples to determine changes in weight in relation to change in temperature.

A derivative weight loss curve can be used to tell the point at which weight loss is most apparent

TA Instruments TGA 2050

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TGA

Weight Loss Stages (%)Weight Loss Stages (%)

BeforeBefore400400ooCC

400400--450--450ooCC

AboveAbove 500500ooCC

RemainRemain

Sample 1Sample 1 5.15.1 7.67.6 77.177.1 00

Sample 3Sample 3 5.45.4 7.47.4 79.479.4 00

Sample 2Sample 2 9.19.1 N/AN/A 85.185.1 5.85.8

*Sample 1: new garment fabric Sample 3: fabric coupon exposed 18hr+ Sample 2: fabric from retired garment

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TGA

The first stage of weight loss might due to fiber moisture or oil containments

The second stage of weight loss might be caused by decomposition of additives such as dye, pigment or other smaller molecular polymer mixtures.

The third stage which is the main weight loss is due to the burning of fiber itself.

Sample 3 has remaining (5.8%), that could be inorganic or metal substances that absorbed by fiber during fire events

Different weight loss % in different stage revealed change of fiber structures

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IGA

Interstitial Gas Analysis (IGA) is a technique appropriate for bulk analysis of H, C, N, O and S, by detecting CO (for C) , SO2 (for S), infrared (O as in CO by NDIR) or thermal conductivity (N and H by TCD) while heating up the Sample.

Done at EAGSM.

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IGA (Outer Shell layer )

SymbolSymbol ElementElementConcentration (wt%)Concentration (wt%)

Sample 1Sample 1 (New)(New)

Sample 3Sample 3 (Used)(Used)

Sample 2Sample 2 (Old)(Old)

C Carbon 58 65 59

N Nitrogen 2.8 5.6 3.1

O Oxygen 14 15 17

S Sulfur 0.029 0.057 1.9

H Hydrogen 4.4 3.9 4.1

Concentration of sulfursulfur in Sample 2 was 65 times65 times than Sample 1, 33 times33 times than Sample 3, while other concentrations of elements were almost the same

This revealed that sulfur was gradually accumulated on the surface or absorbed by cloth fibers

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IGA (Different Layers)

The outer shell layer absorb most sulfur on surface; the concentrations of sulfur on internal layers are most zero

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XRF X-ray Fluorescence (XRF) is the

emission of characteristic "secondary" X-rays that has been excited by bombarding with high-energy X-rays or gamma rays.

The main purpose of XRF test to analyzed chlorine concentration. The X-ray beam was rastered over an area to obtain a representative sample. Two locations were measured on the sample.

Quantification of Chlorine was performed by calibrating against a PVC sample with a known Cl concentration.

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XRF (Outer Shell Layer)

*Sample 1: new garment fabric Sample 3: fabric coupon exposed 18hr+ Sample 2: fabric from retired garment

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XRF (Different Layers)

The outer shell layer absorb most toxic elements on surface; the concentrations on internal layers are most zero

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XRF

It revealed that Sulfur and Chloride accumulated into the fiber sample

Other inorganic elements, such as K, Ca, Ti and etc. were also found. These might come from inorganic materials and paintings on wall during fire event

Possible explanation that old fabric (sample 2) had considerable high weight remaining percentage in TGA test.

The outer shell layer absorb most toxic elements on surface; the concentrations on internal layers are most zero

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Conclusions

The conducted analysis showed that the exposed garment contains a lot of harmful chemical species absorbed into the fabric.

The exposed fabric reveals decreased mechanical strength and wear.

EDS, IGA and XRF results revealed that the concentration of sulfur, nitrogen, chloride elements which represent possible toxic containments are much high in used garment fiber.

Other inorganic elements such as K, Ca, Ti were also founded, confirmed by TGA when there is 5.8% remaining at 900oC.

The outer shell layer absorb most toxic elements on surface; the concentrations on internal layers are showing an exponential decay

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Future Work

The goal is to develop approach for evaluation of the protective garment for firefighters which will be able to predict when the garment should be retired

The ultimate goal is to develop a multi-functional sensor incorporated into the garment that will be able to measure body temperature, concentration of the penetrating gas species, moisture level, heart rate, etc.

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Acknowledgement

This research study was supported by the National Institute of Occupational Safety and Health and the Health Pilot Research Project

Training Program of the University of Cincinnati Education and Research Center Grant #T42/OH008432-04. The authors thank Prof. Amit

Bhattacharya for the valuable scientific discussion related to the proposed research.

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References

Alarie, Y. (2002). "Toxicity of Fire Smokes." Critical Reviews in Toxicology 32(4): 259-289.

Mahall, K. (2003). Quality Assessment of Textiles. New York, Springer-Verlag Berlin Heidelberg.

Meyer, E. (2004). Chemistry of Hazardous Materials. Upper Saddle River, Pearon Education, Inc.

Raheel, M. (1995). Modern Textile Characterization Methods. New York, Marcel Dekker, Inc.

V.S. Ramachandran, R. M. P., James J. Beaudoin, Ana H. Delgado (2002). Handbook of Thermal Analysis of Construction Materials. Norwich, Noyes Publications.

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Q & A