7.3 HAZARDOUS

ATMOSPHERES

ENABLING OBJECTIVES

• DESCRIBE the hazards of flammable or toxic gases and vapors.

• DESCRIBE the physical characteristics of common gases, solvents and fuels.

• DESCRIBE shipboard locations of various explosive or toxic gases or mixtures of gases may be encountered.

• DESCRIBE the sources of explosive or toxic gases in the shipboard environment.

• Calculate the combined toxicity levels for combined concentrations of harmful gases

7.02 HAZARDOUS ATMOSPHERES REFERENCES:(a) 29 CFR 1910.1000, OSHA Permissible Exposure limits(b) NWP 3-20.31, Surface Ship SurvivabilityOPNAVINST 5100.19 (series), NAVOSH Program Manual for Forces Afloat(c) NSTM 074 Vol. 3, Gas Free Engineering

WHY ARE TERMS AND DEFINITIONS IMPORTANT?

•You, the GFE, must be able to use and understand terms

•Prevents misunderstandings between you, military personnel, and civilian personnel (think liability!)

•Lends credibility to your qualifications and your program

IMMEDIATELY DANGEROUS TO IMMEDIATELY DANGEROUS TO LIFE OR HEALTH (IDLH)LIFE OR HEALTH (IDLH)

• Any atmosphere that meets one or more of the following conditions

Oxygen content < 19.5 or > 22%Flammable vapors at a concentration of

10% or > LEL Presence of toxicants above NIOSH

IDLH limits

(Found in Appendix G of 074 Vol. 3)

PERMISSIBLE EXPOSURE PERMISSIBLE EXPOSURE LIMIT (PEL)LIMIT (PEL)

• The maximum permissible concentration of a toxic agent to which personnel may be exposed.

• Published by OSHA

• Based on a TWA for a normal 8-hour day, 40 hour, 7-day week

• Expressed in parts per million (ppm)

• Single toxicants only

CONFINED SPACECONFINED SPACE

• Limited and restricted accesses• Lack of natural ventilation• May contain or produce hazardous

contaminants or oxygen deficiencies or enrichment

• Not intended for continuous occupancy

• Tanks• Voids• Interior machinery (boilers,

condensers, oil sumps)• Non-ventilated storerooms• Ventilation & Exhaust ducts

CONFINED SPACESCONFINED SPACES

Gas Free Engineers:What Are You Testing For?

O E TOXYGEN

EXPLOSIVES

TOXICANTS

OXYGEN

Normal at Sea Level

22 %

20.9 %

19.5 %

12 %

10 %

8 %

6 %

4 %

OXYGEN

Wide Awake, Hyper Vigilant22 %

20.9 %

19.5 %

12 %

10 %

8 %

6 %

4 %

OXYGEN> 26 % O2, Spontaneous Combustion Can Occur

> 22 % Oxygen is Considered IDLH Due to Exceptional Risk of Fire

22 %

20.9 %

19.5 %

12 %

10 %

8 %

6 %

4 %

OXYGEN

Loss of Coordination, Loss of Perception, Lack of Judgment

< 19.5 % Oxygen Considered IDLH by OSHA -- Entry Requires CO’s Permission

22 %

20.9 %

19.5 %

12 %

10 %

8 %

6 %

4 %

OXYGEN

Blue Lips, Disorientation

22 %

20.9 %

19.5 %

12 %

10 %

8 %

6 %

4 %

OXYGEN

Vomit

22 %

20.9 %

19.5 %

12 %

10 %

8 %

6 %

4 %

OXYGEN

Unconscious 5 min : Could recover 6 min: 50% Fatal 8 min: 100% Fatal

22 %

20.9 %

19.5 %

12 %

10 %

8 %

6 %

4 %

OXYGEN

Coma in 40 Seconds

22 %

20.9 %

19.5 %

12 %

10 %

8 %

6 %

4 %

OXYGEN

Just Remember . . .

Oxygen Levels Greater than 22% or Less than 19.5% are IDLH !

DeathX X

22 %

20.9 %

19.5 %

12 %

10 %

8 %

6 %

4 %

Reasons for Oxygen deficiency

• EductorsEductors

• FiresFires

• Rusting (Oxidation)Rusting (Oxidation)

• InertingInerting

• Decomposing Organic MatterDecomposing Organic Matter

-- Sewage-- Sewage

-- Fermentation of grains, sugars, etc.-- Fermentation of grains, sugars, etc.

-- Rotting plant or marine life-- Rotting plant or marine life

% Vapor Concentration

UEL

LEL

Too Rich

Too Lean

Explosive Range

Exp

losi

vity

10%

Levels Near LEL Leave No Buffer for Explosive Gas Build-Up Greater Than 10% LEL is

Considered IDLH -- and Requires CO’s Permission for Entry

EXPLOSIVES

Toxic Gas Common Shipboard Hazards

Carbon MonoxideHydrogen Sulfide

Halon & Freon

Carbon Dioxide

Nitrogen Dioxide

Methane

HydrogenAmmonia

Carbon Dioxide

Carbon Monoxide

Hydrogen Chloride

Hydrogen Cyanide

Hydrocarbons

Carbon Monoxide (CO)

FROM INCOMPLETE COMBUSTION

COLORLESS, ODORLESS, TASTELESS

LIGHTER THAN AIR

SUBTLE ASPHYXIANT

FLAMMABLEWhere Onboard Ship?

P-100s, Post-Fire Atmosphere, Diesel Generators, Paint Drying

ORGANIC DECAY

COLORLESS GAS

ROTTEN EGG SMELL

HEAVIER THAN AIR

FLAMMABLE

Attacks Nerves:

Apnea, Coma

Anaerobic Organic Decay

WHERE H2S HIDES: FIREMAIN

AFFF SYSTEM

ROTTING FOOD

GARBAGE GRINDER

SEWAGE SPACES

Hydrogen Sulfide (H2S): #2 Killer of Sailors

AEROBIC:

(with oxygen) decomposition and stabilization.

ANAROBIC:

(without oxygen) decomposition.

FREON (R-12, R-113, R-134)Colorless, Odorless, Heavier

Than AirNON-FLAMMABLE:

RUSSIA USES FREON FOR F/F

FrostbiteBlunt Asphyxiant, Attacks Nervous System, Dry Land

Drowning

Colorless, Odorless, Heavier Than Air

NON-FLAMMABLE:

RUSSIA USES FREON FOR F/F

FrostbiteBlunt Asphyxiant, Attacks Nervous System, Dry Land

DrowningReefer Decks, A/C PlantsReefer Decks, A/C Plants

Phosgene Phosgene

HALON 1301 (BromoTriFlouroMethane)

Colorless, Odorless5 Times Heavier Than Air

FrostbiteAttacks Nervous System, Dry Land

Drowning

Decomposes at High Temps: HF, HCl, HBr

HALON 13015 - 7 % for 10 min: No Health Danger

7 - 10% : Dizziness, Tingling Extremities, Mild Anesthesia

> 10 % : Very Dizzy, Nearly Unconscious, Lose Physical & Mental Dexterity

CO

2 FL

OO

DIN

G S

YS

TE

M

Colorless, Odorless, Tasteless, Inert HEAVIER THAN AIR

Blunt Asphyxiant NON-FLAMMABLE

Carbon Dioxide (CO2)

Portable CO2

CO2 Flooding

• DARK BROWN, PUNGENT GAS

• CHOKING AGENT -- Absorbed

• HEAVIER THAN AIR

• NON FLAMMABLE

Nitrogen Dioxide (NO2)

Produced From Hot Work, Fires, &

Internal Combustion Engines

Smoldering Polyester, Wool & Nylon

Tank Pressed Up & Heated

COLORLESS, ODORLESS GAS

LIGHTER THAN AIR

EXTREMELY EXPLOSIVE

AEROBIC ORGANIC DECAY

Methane (CH4)

PUNGENT ODOR

LIGHTER THAN AIR

FLAMMABLE

CHOKING AGENT

Ammonia (NH3)

CLEANING PRODUCTS, URINALS

ODORLESS, COLORLESS GAS

LIGHTER THAN AIR

EXTREMELY EXPLOSIVE

Hydrogen (H)

LEAD-ACID BATTERIES

RUST

C METHANEC-C BUTANEC-C-C-C-C PENTANEC-C-C-C-C-C-C-C OCTANE

BENZENE

TOLUENE

XYLENE

BENZENE

TOLUENE

XYLENE

Finding Hydrocarbons

Fuel VaporsPaintsSolvents

How do you know what toxicants to test for in a space?

Appendix EHow do you know what Draeger Tubes are available?

Appendix LHow do you know the PEL and IDLH limits for Toxicants?

Appendix G

IDLH

Respiratory Protection OptionalRespiratory Protection Optional

Respiratory Protection Mandatory(Filter Type Respirator

or Supplied Air Respiratoras Appropriate)

Respiratory Protection Mandatory(Filter Type Respirator

or Supplied Air Respiratoras Appropriate)

Supplied Air Respirator in pressure demand mode (SCBA) or Supplied Air Respirator (SAR)w/

15 minute backup Air (SCBA)Required

Supplied Air Respirator in pressure demand mode (SCBA) or Supplied Air Respirator (SAR)w/

15 minute backup Air (SCBA)Required

PEL

UNITY EQUATION“If there is more than one toxicant

product in a space undergoing testing, the cumulative effects of the two or more products may be above unity, even though the PELs for any one of the products has not been exceeded.”

NSTM 074-19.11 (p74-14)

UNITY EQUATION

C1/T1 + C2/T2 + ... = 1WHERE:

C is the Measured Concentrations of Toxic Substances

and

T is the Toxic Limit : PEL or TLV (whichever is lowest)

DETERMINE IF THE COMBINED TOXIC EFFECTS OF THE FOLLOWING GASES

EXCEEDS THE ALLOWABLE PERMISSIBLE EXPOSURE LIMIT ON A TWA.

ACTUAL PELToluene 80 ppm 200 ppmCarbon Monoxide 25 ppm 50 ppmXylene 40 ppm 100 ppm

(Remember, C1/T1 + C2/T2 + ... = 1)

UNITY EQUATION

Ce/Te + Ct/Tt + Cn/Tn < 1 80200

+ 25 50

+ 40100

=

1.3 > 1 SO IT EXCEEDS LIMIT

Therefore, Respiratory Protection is Mandatory

ACTUAL PELToluene 80 ppm 200 ppmCarbon Monoxide 25 ppm 50 ppmXylene 40 ppm 100 ppm

.4 + .5 + .4 = 1.3

UNITY EQUATION

Questions????Questions????

SUMMARY – We described the hazards of

flammable or toxic gases and vapors.

•We described the physical characteristics of common gases, solvents and fuels.

•We described shipboard locations of various explosive or toxic gases or mixtures of gases may be encountered.

•We described the sources of explosive or toxic gases in the shipboard environment.

•We calculated the combined toxicity levels for combined concentrations of harmful gases

REVIEW Questions - When is the Oxygen Level Considered IDLH?REVIEW Questions - When is the Oxygen Level Considered IDLH?

Greater than 22%, Less than 19.5%Greater than 22%, Less than 19.5%When are Explosives Considered IDLH?When are Explosives Considered IDLH? Greater than 10% LELGreater than 10% LEL

Name 4 Toxicants that are HEAVIER than Air:Name 4 Toxicants that are HEAVIER than Air: CO2, H2S, HALON, FREONCO2, H2S, HALON, FREON

Name 3 Toxicants which are LIGHTER than Air:Name 3 Toxicants which are LIGHTER than Air: CO, Ammonia, Hydrogen, MethaneCO, Ammonia, Hydrogen, Methane

Name 2 Toxicants that can Cause a Sailor to Choke:Name 2 Toxicants that can Cause a Sailor to Choke: Nitrogen Dioxide, AmmoniaNitrogen Dioxide, Ammonia