Gas Odorants Health, Environment and Safe Handling

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Gas OdorantsHealth, Environment and Safe Handling

• Gary Alford
• Technical Sales Manager
• Vicente Santa Cruz, Ph.D. DABT
• Senior Toxicologist
• Chevron Phillips Chemical Company LP

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Take Home Messages

• By the end of the this workshop you should
• Understand why we odorize Natural Gas and Liquid
  Propane Gas
• Identify odorant base components and odorant
  hazards
• Learn ways to reduce/minimize employee and
  environmental exposure
• Identify where to obtain hazard information
• Identify essential players in time of emergency
  situations
• Understand how to incorporate resources in
  emergency situations

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Discussion Topics

• Regulations
• Odorant Characterization
• Odorant Hazards, Exposure and Risk
• Safe Handling Procedures

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Odorant Regulations
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Why Odorize?

• For System and Customer Safety
• To protect those who work daily with the gas
  pipeline system
• and most importantly, to protect the end
  usersour families

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New London, TexasWake Up Call

• Rich rural school district in northwestern oil
  field region
• Modern steel framed building
• 500 students and teachers in building at 305pm

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New London, TexasWake Up Call

• Explosion ignited by switch of a sanding machine
• 298 Children and Teachers died
• 130 Escaped serious injury

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Why Odorize ?
It is a regulatory requirement. .gas delivered
to customers must be odorized.

• United States Federal Register
• 49 CFR 192.625(a)
• Natural gas must be odorized so that
• any leaks are readily detectable, by a
• person with a normal sense of smell,
• when the concentration of natural gas
• reaches 1/5th of the lower explosive
• limit (LEL)

• Canadian Standards Organization
• Z662-99 Sect. 4.17.1
• Fuel gas that is to be delivered to
• customers through distribution or
• service linesand that does not
• naturally possess a distinctive odor to
• the extent that its presence in the
• atmosphere is readily detectable at all
• gas concentrations not less than one
• fifth of the lower explosive limit shall
• have an odorant added to it to make it
• detectable.

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Why Odorize ?
Too Rich...
Regulations wisely built in a safety factor so
that a gas leak is readily detectable by human
beings well below the percentage in air required
to form an explosive mixture...
Boom!
Too Lean
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Why Odorize ?
.operating companies must test and confirm
concentrations.

• Canadian Standards Organization
• Z662-99 Sect. 10.12.2
• Operating companies shall
• sample and test odorized gases to
• confirm that the concentrations of
• the odorant are appropriate.

United States Federal Registry 49 CFR
192.625(f) Each operator shall conduct periodic
sampling of combustible gases to assure the
proper concentration of odorant in accordance
with this section
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Odorant Characterization
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Chemical Characteristics

• What Makes an Acceptable Odorant?
• Strong Odor at Low Concentrations
• Relatively Unreactive
• Low Toxicity
• Low Water Solubility
• Relatively Inexpensive

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Chemical Characteristics
Liquid Propane Gas Odorant
Ethyl Mercaptan CH3CH2-S-H
Natural Gas Odorants
Alkyl Mercaptans R-S-H
Cyclic Sulfides
Alkyl Sulfides R-S-R
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Formation Pathways
Mercaptans
CH2CH2 H2S
CH3CH2-S-H (EM)
(CH3)2CCH2 H2S
(CH3)3C-S-H (TBM)
Sulfides
CH3-S-CH2CH3 (MES)
CH3SNa CH3CH2Cl
(CH2)4O H2S
(CH2)4S (THT)
CH3OH H2S
CH3SH CH3-S-CH3 (DMS)
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Chemical Characteristics
Typical Mercaptans
n-Propyl Mercaptan (NPM)
sec-Butyl Mercaptan (SBM)
Isopropyl Mercaptan (IPM)
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Chemical Characteristics
Typical Sulfides
Methyl Ethyl Sulfide (MES)
Thiophane (THT)
Dimethyl Sulfide (DMS)
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Typical Odorants
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Odorant Hazards, Exposure and Risk
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Basics of Toxicology

• Paracelsus (1493-1541) Created scientific
  discipline of toxicology-coined the phrase
• The Dose Makes the Poison

• All substances are poisons there is none which
  is not a poison. The right dose differentiates a
  poison and a remedy.

RISK
EXPOSURE
HAZARD
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How much is good or bad?
B.
D.
A.
C.
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MSDS provide health, physical, and environmental
hazards
Chemical Information
Where can we find a Chemicals Hazard Information?
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Measurement Expression
ppm 1 minute in 2 years
or
ppb 1 second in 32 years
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ODOR THRESHOLDS
Physical/Chemical Properties

• Ethyl Mercaptan or TBM
• 0.0000001 ppm or 0.1 ppb
• H2S
• 0.0005 ppm or 0.5 ppb
• SO2
• 0.708 ppm

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FLAMMABILITY
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Is it Toxic?
OSHA Classification of Acute Lethality
LC50 / LD50 Lethal Concentration/Dose for 50
of animals
Dermal Oral
Inhalation
mg/kg mg/kg
ppm Nontoxic gt1000 gt500
gt2500 Toxic gt200-1000
gt50-500 gt1500lt2500 Very Toxic lt 200
lt 50 lt 1500
-
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Acute Health Effects
 

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Long-Term Health Effects

• Not expected to be carcinogenic based on current
  and available information for odorant blend
  stocks.
• Corroborating data from genetic toxicity testing
  indicate that odorant blend stocks are not
  expected to be mutagenic in humans.
• No human reports of cancer caused by exposure to
  gas odorants or their components have been
  documented to this date.
•  
• Not expected to induce developmental or
  reproductive toxicity based on information for
  odorant blend stocks.

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Summary of Health Hazards

• Lung aspiration hazard Do not induce vomiting.
• Mild to severe irritants TBM is a sensitizer,
  THT is a severe irritant.
• Central Nervous System (CNS) depression Vapors
  cause headache, dizziness, nausea, vomiting.
• CONCERN IS FLAMMABILITY AND COMBUSTION PRODUCTS
  (SO2)

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Aquatic Toxicity Biodegradability
Aquatic Toxicity EM - Toxic to Fish, Very Toxic
to Daphnia NBM - Very Toxic to
Daphnia NPM - Toxic to Daphnia TBM - Harmful to
Fish and Algae, Toxic to Daphnia THT
- Not Available (not marine pollutant) Biodegrada
bility EM - 28 Not Ready Biodegradable THT -
48 Expected to be Biodegradable NPM, NBM, TBM
- gt90 Ready Biodegradable
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Summary of Environmental Effects

• TBM
• Ethyl Mercaptan
• NPM
• THT

• TOXICITY
• Aquatic Biodegradability
• Toxic Readily
• Toxic Not Readily
• Toxic Readily
• NA Expected

Ethyl Mercaptan is classified as a MARINE
POLLUTANT
LOW ORDER OF TOXICITY
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Gas and Odorant Concentrations
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Concentration Effects
THT OEL 1 ppm
TBM OEL 1 ppm
1000 ppm
4420 ppm
EM OEL 0.5 ppm
1 ppb
2500 ppm
1 ppm
50 Death Animals
Contained
IDLH
Odor
4000X
4 ppm Symptoms
2,500,000X
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Occupational Exposure Levels

• MeSH 0.5 ppm
• Mercaptans 5.0 ppm
• n-Butyl Mercaptan 0.5 (TWA)
• THT 1.0 ppm
• Ethyl Mercaptan 0.5 ppm (TWA)
• 10 ppm (Ceiling)
• 2500
  ppm (IDLH)

Based on odor, Chevron Phillips Chemical
recommends a permissible exposure level
(8-hr.TWA) of 1 ppm for tert-Butyl mercaptan.
4 ppm may cause minimal symptoms (headache,
fatigue, nausea) 500 ppm may be hazardous per
Mercaptans
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Personal Protection Equipment

• Ventilation Use adequate ventilation to
  control exposure below
• recommended levels.
• Respiratory Protection For concentrations
  exceeding the recommended
• exposure level, use NIOSH
  approved air purifying respirator. In
• case of spill or leak
  resulting in unknown concentration, use
• NIOSH approved supplied air
  respirator.
• Eye Protection Use safety glasses with side
  shields. For splash protection
• use chemical goggles and
  face shield.
• Skin Protection Neoprene gloves if liquid
  splashes
• could occur. Use protective
  garments
• to prevent excessive skin
  contact.

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Personal ProtectionEquipment

• Air-Purifying Respirators Use cartridges to
  purify ambient air (e.g., Half-mask, Full Face
  Piece)
• Supplied-Air Respirator Air is supplied to the
  face piece under positive pressure (air line or
  SCBA)

Use Yellow-Organic Vapor
In emergency situations, use only an SCBA.
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TAKE HOME

• Low odor thresholds ALARM
• Listen to public complaints of odors long-term
  exposure can cause desensitization
• Flammable
• Odorants have low order of toxicity due to
  mercaptan composition
• Toxicity dependent on exposure dose

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Emergency Handling Procedures
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Spill Response
CONTAIN the spill ABSORB the spill NEUTRALIZE and
MASK the odor DISPOSE of the material
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Containment

• CONFINE versus CONTAIN the spill
• Shut off all ignition sources in the spill area
• Treat as Class 3 flammable material
• Stop leakage that caused the spill
• Contain within closed area if possible
• Keep from getting into water source
• Use catch bucket filled with neutralizing agent

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Absorption

• ABSORB the spill
• Commercial absorbent material can be used to
  knock down odors
• Commercial powder absorbents
• Sand, clay or other kinds of soil
• Sawdust, kitty litter
• Commercial absorbent pads
• Cover spill
• Tarps, plastic sheets
• Vapor suppression
• Alcohol Resistant AFFF Foam

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Neutralize and Mask

• NEUTRALIZE and MASK the odor
• Live Bacteria solutions
• Slow biochemical oxidation
• Add soap to increase adhesion properties
• Add anti-freeze to decrease freezing point
• Masking Agents
• Do not oxidize only mask odors
• Dilute bleach solutions
• Efficient and quick oxidizing agent
• Caution Exothermic reaction with mercaptans
• Household bleaches
• 5 solution of sodium hypochlorite (i.e. Clorox
  Bleach)
• CAUTION
• NEVER USE POWDER BLEACHES
• NEVER USE CHLORINE BLEACH, i.e. SWIMMING POOL
  BLEACHES
• Do not use on large spills
• Must treat waste as hazardous material

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Reaction Chemistry
Formation Chemistry
CH2CH2 H2S
CH3CH2-S-H (EM)
(CH3)2CCH2 H2S
(CH3)3C-S-H (TBM)
(CH2)4O H2S
(CH2)4S (THT)
CH3-S-CH2CH3 (MES)
CH3SNa CH3CH2Cl
Decomposition Chemistry
(CxHy)zCCH2 H2S
EM or TBM
Heat
No Reaction
MES, THT or DMS
Burn
CXHY SO2 SO3 H2SO4
EM, TBM, MES, THT or DMS
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Chemical Reaction Pathways
Reaction with Bleach

• R-S-H 3 NaClO

R-SO3-H 3 NaCl
Reaction with Peroxide
R-S-H 3 HOOH
R-SO3-H 3 OH-
Reactions with Bacteria
R-S-H Bacteria O2 H2O
CO2 H2O H2SO4
Masking Agent

• Masking properties, no chemical reaction
• Highly fragrant chemicals in family of Terpenes
• Myrcene (Bay Leaves), Menthol (Peppermint Oil),
  Geraniol (Geraniums)

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Disposal and Decontaminate

• DISPOSE of material
• As directed by Environmental quality personnel or
  agency
• Do not use water to spray down area
• Ethyl mercaptan is marine toxin
• Remove dirt or asphalt
• Place in sealed containers to control odors
• Decontaminate site
• As directed by Environmental quality personnel or
  agency
• Concrete surfaces treated with bleach water
• Treat liquid as hazardous material
• Soil contamination
• Bioremediation may be possible
• Remove the liquid
• Vacuum trucks
• Large liquid spills