Energy Symposium - Combined Session Roughnecks & Master Drillers 8/12/2010. H 2 S It will kill you dead like a rock. Notes. H2S - Charlie Scott 1

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1 H 2 S It will kill you dead like a rock Notes 3 H2S - Charlie Scott 1

2 H 2 S - Hydrogen Sulfide It will kill you dead like a rock H 2 S Safety Factsheet Hydrogen sulfide (H 2 S, CAS# ) is an extremely hazardous, toxic compound. It is a colorless, flammable gas that can be identified in relatively low concentrations, by a characteristic rotten egg odor. The gas occurs naturally in coal pits, sulfur springs, gas wells, and as a product of decaying sulfur-containing organic matter, particularly under low oxygen conditions. It is therefore commonly encountered in places such as sewers, sewage treatment plants (H 2 S is often called sewer gas), manure stockpiles, mines, hot springs, and the holds of fishing ships. Industrial sources of hydrogen sulfide include petroleum and natural gas extraction and refining, pulp and paper manufacturing, rayon textile production, leather tanning, chemical manufacturing and waste disposal. H 2 S Safety Factsheet Hydrogen sulfide has a very low odor threshold, with its smell being easily perceptible at concentrations well below 1 part per million (ppm) in air. The odor increases as the gas becomes more concentrated, with the strong rotten egg smell recognizable up to 30 ppm. Above this level, the gas is reported to have a sickeningly sweet odor up to around 100 ppm. However, at concentrations above 100 ppm, a person's ability to detect the gas is affected by rapid temporary paralysis of the olfactory nerves in the nose, leading to a loss of the sense of smell. This means that the gas can be present at dangerously high concentrations, with no perceivable odor. Prolonged exposure to lower concentrations can also result in similar effects of olfactory fatigue. This unusual property of hydrogen sulfide makes it extremely dangerous to rely totally on the sense of smell to warn of the presence of the gas. H2S - Charlie Scott 2

3 Hazards & Characteristics Principle Hazard is Death by Inhalation When the amount of gas absorbed into the blood stream exceeds that which is readily oxidized, systemic poisoning results, with a general action on the nervous system. Labored respiration occurs shortly and respiratory paralysis will follow immediately at higher concentrations. Death will occur from asphyxiation unless the exposed person is immediately removed to fresh air and breathing stimulated by rescue breathing. Other levels of exposure may cause the following symptoms individually or in combination: Headache Dizziness Excitement Nausea Coughing Drowsiness Dryness and pain in nose, throat and chest Detection of H 2 S solely by smell is highly dangerous as the sense of smell is quickly paralyzed by the gas. 1. Extremely Toxic, ranking 2nd to Hydrogen Cyanide (HCN) and five (5) to six (6) times more toxic than Carbon Monoxide (CO) 2. Colorless gas in its pure state 3. Offensive odor, often described as that of rotten eggs H2S - Charlie Scott 3

4 4. Heavier than air - Vapor Density (Air = 1.0) Vapors may travel considerable distance to a source of ignition and flashback. 5. Forms an explosive mixture with air in concentrations between 4.3% (LEL/LFL) and 46% (UEL/UFL) by volume 6. Auto-ignition temperature of 500 o F; Cigarette burns at 1,400 o F 7. Burns with a blue flame and produces Sulfur Dioxide (SO 2 ), which is less toxic than H 2 S, but highly irritating to eyes and lungs and can cause serious injury. Chemical pneumonia (pulmonary edema) can develop in only a few hours. 8. Soluble in both water and liquid hydrocarbons. H 2 S dissolves in water forming a weak hydrosulfuric acid. 9. Produces irritation to eyes, throat, and respiratory system 10. Threshold Limit Value / Time Weighted Average (TLV/TWA - ACGIH) maximum of eight (8) hour exposure without respiratory protection - 10 PPM 11. Permissible Exposure Limit / Time Weighted Average (PEL/TWA - OSHA) maximum of eight (8) hour exposure without respiratory protection - 10 PPM (Note: The PEL for H 2 S is unpublished which means OSHA incorporated the 10 PPM by reference from the ACGIH TLV s) 12. Short Term Exposure Level (STEL) - 15 PPM for 15 minutes; maximum four (4) times in an eight (8) hour day; excursions at least one (1) hour apart 13. Heat generated by burning H 2 S: 680 BTU/ft H 2 S attacks most metals, especially in the presence of water, forming sulfides which are generally insoluble precipitates. Acidizing, or lowering the ph of this liquid below about 8.1 (7.0 is neutral), tends to permit the gas to evolve from the liquid. 15. Corrosive to plastics, elastomers, animal tissues and nerves. 16. Causes hydrogen embrittlement or sulfide stress cracking (SSC) in the harder metals. Maximum hardness for metals exposed to H 2 S in Rockwell(C) or 235 Brinnell. 17. In certain applications, can form a pyrophorric substance called Iron Sulfide. This substance will auto-ignite when exposed to air. H2S - Charlie Scott 4

5 18. Immediately Dangerous to Life or Health (IDLH) 18. Immediately Dangerous to Life or Health (IDLH) The value at which a substance renders an individual incapable The value at which a substance renders an individual of self-rescue from a hazardous environment within 30 minutes and incapable of self-rescue from a hazardous environment within may cause permanent eye damage. For Hydrogen Sulfide that 30 minutes and may cause permanent eye damage. For value is 100 ppm. Hydrogen Sulfide that value is 100 ppm. Notes Notes H2S - Charlie Scott 5

6 Health Effects of Hydrogen Sulfide H 2 S is classed as a chemical asphyxiant, similar to carbon monoxide and cyanide gases. It inhibits cellular respiration and uptake of oxygen, causing biochemical suffocation. Typical exposure symptoms include: L O W Typical exposure symptoms include: 0-10 ppm Irritation of the eyes, nose and throat M O D ppm Headache Dizziness Nausea and vomiting Coughing and breathing difficulty H I G H ppm Severe respratory tract irritation Eye irritation / acute conjunctivitis Shock Convulsions Coma Death in severe cases Prolonged Low Level exposure symptoms include: Prolonged exposures at lower levels can lead to bronchitis, pneumonia, migraine headaches, pulmonary edema, and loss of motor coordination. H2S - Charlie Scott 6

7 Working with Hydrogen Sulfide Working with Hydrogen Sulfide Most countries have legal limits in force that govern the maximum allowable levels of exposure to hydrogen sulfide in the working environment. A typical permissible exposure limit in many countries is 10 ppm. While the distinctive odor of H 2 S is easily detected, its olfactory fatigue effects mean that one cannot rely on the nose as a warning device. The only reliable way to determine exposure levels is to measure the amount in the air. Working with Hydrogen Sulfide With a vapor density of 1.19, hydrogen sulfide is approximately 20 percent heavier than air, so this invisible gas will collect in depressions in the ground and in confined spaces. The use of direct reading gas detection instrumentation should be required before entering confined spaces such as manholes, tanks, pits, and reaction vessels that could contain an accumulation of H 2 S gas. H2S - Charlie Scott 7

8 Use in Suicide In 2008, according to an article in Wired magazine, a mixture of bath sulfur and toilet bowl cleaner that released hydrogen sulfide became popular with people seeking to end their lives in Japan. A related USA Today article reported that 517 Japanese people killed themselves using hydrogen sulfide during the first half of the year. Wired reported that the a similar technique was later in vogue with suicides in the U.S. as well. Hydrogen sulfide is an extremely dangerous way to commit suicide because people who later enter the room or other residents of the same building may also be exposed to toxic concentrations of the gas and become unintended victims Signaling Molecule A signaling molecule is a chemical involved in transmitting information between cells. Such molecules are released from the cell sending the signal, cross over the gap between cells, and interact with receptors in another cell, triggering a response in that cell. Notes H2S - Charlie Scott 8

9 The Ten Commandments of Hydrogen Sulfide (H 2 S) Safety Hydrogen Sulfide (H 2 S) Safety 1. Thou shall learn about this poisonous gas called H 2 S, sour gas, stink damp, etc. (It is very poisonous!) that thy days in this land may be long enough for thee to collect thy Social Security. 2. Thou shall know that H 2 S temporarily destroys the sense of smell after the first whiff or three, so that thee may no longer smell the gas and may falsely think that the gas has blown away, when in fact it may not have done anything of the sort. Thou shall know in thy heart that H 2 S is a product of putrefaction. (How do thee think it got that odor of rotten eggs?) Hydrogen Sulfide (H 2 S) Safety 3. Thou shall realize that the maximum H 2 S thou should breathe in an eight-hour period is 10 ppm (10 parts of H 2 S to 1,000,000 parts of air equals 10 ppm; this is an 0.001% concentration of the gas) 4. Thou shall always remember that lower concentrations of H 2 S produces irritation to the eyes, throat and respiratory tract, and may produce coughing, eye burning, and/or sleepiness. 5. Thou shall never forget that concentrations of H 2 S over about 500 ppm (0.05%) may well knock thee out and cause thee to fall with a thud from thy perch, perhaps busting thy butt or breaking thy neck, or drowning thee in water or oil. H2S - Charlie Scott 9

10 Hydrogen Sulfide (H 2 S) Safety 6. Thou shall come to know in thy heart that H 2 S concentrations over 600 ppm (0.06%) likely will gather thee to thy ancestors PDQ! 7. Thou shall covet for thy own use the best approved air mask and personal monitor for H 2 S when thy work requires that thee enter an area where the concentrations IS or MAY BE above safe levels. 8. Thy mind shall come to know that H 2 S is colorless so that the eye cannot perceive it, and that it is heavier than air so that it settles in low places. Hydrogen Sulfide (H 2 S) Safety 9. Remove thy neighbor (or co-worker) to fresh air at once if he should fall victim to H 2 S. Remember to exercise due caution in the rescue lest thee, too, fall to the smelly gas. Render rescue breathing unto thy fallen neighbor if he be unconscious and not breathing, that the breath of life may be sustained in him. Get the fallen one to a physician with great haste. 10. Demand not that thy God protect thee from thy foolishness when thou tread where angels fear to go, for thy God gave thee a brain and expects thee to use it! Target Organs Hydrogen sulfide is a toxic and irritant gas whose major effects are exerted on the nervous system, the eyes and the respiratory tract. Other target organs/body structures affected include the brain and olfactory nerves. Olfactory Nerves: Loss of sense of smell occurs within 3-5 minutes at 100 ppm Brain: Headaches, nausea, dizziness, confusion, brain damage H2S - Charlie Scott 10

11 Acute vs. Chronic Exposures Acute: (Short Term) Generally defined as exposure to high concentration for short duration Chronic: (Long Term) Generally defined as exposure to low concentration for a longer duration 31 Signs and Symptoms of Acute Toxicity Olfactory Paralysis Eye Irritation Headaches Nausea Diarrhea Dizziness Confusion Staggering Gait Cardiac Arrest Excitement Coughing Sneezing Respiratory Irritation Pulmonary Edema Respiratory Arrest Brain Damage Photophobia Signs and Symptoms of Chronic Toxicity Eye Irritation Corneal Blistering, Pitting, Opacity Headaches Nausea Irritation of Respiratory Tract Pulmonary Edema Anorexia Sleep Disturbances H2S - Charlie Scott 11

12 Key Definitions Oxygen Deficient - Atmosphere in which there is not enough oxygen to sustain life. Normal atmosphere contains 20.8% oxygen. An oxygen deficient atmosphere contains less than 19.5% oxygen. Oxygen Enriched - Atmosphere containing more than 23.5% oxygen. Flammable Vapors - Any material in a gas form that will explode when mixed with enough oxygen and exposed to a source of ignition. Upper Flammable Limit (UFL) - Largest concentration of gas or vapor in air which can catch fire or explode when exposed to a source of ignition. UFL for H 2 S = 46% Lower Flammable Limit (LFL) - The smallest concentration of gas or vapor in air which can catch fire or explode when exposed to a source of ignition. LFL for H 2 S = 4.3% LEL / UEL - The flammable range will vary from gas to gas; therefore it is important to know which gas you are testing for. For H 2 S that range is 4.3% - 46% H2S - Charlie Scott 12

13 Flash Point - The lowest temperature at which a liquid gives off enough vapor to form an ignitable mixture with air and produce a flame when a source of ignition is present. For H 2 S the flash point is -76o F. Vapor Density - The weight of a vapor or gas compared to the weight of an equal volume of air. Materials lighter than air have vapor densities less than 1.0 (acetylene, methane, hydrogen). Materials heavier than air (propane, hydrogen sulfide, ethane, chlorine) have vapor densities greater than 1.0. Lighter vapors and gases will tend to rise while heavier vapors are likely to concentrate in low places. H 2 S has a vapor density of 1.189; Air = 1.0 Concentration Comparisons Parts Per Million vs Percentage 1,000,000 ppm = 100% 100,000 ppm = 10% 10,000 ppm = 1% 1,000 ppm = 0.1% 100 ppm = 0.01% 10 ppm = 0.001% 1 ppm = % Trace Concentration Units UNIT 1 PART PER MILLION Length 1 Inch / 16 Miles Time 1 Minute / 2 Years Money 1 Cent / $10,000 Weight 1 Ounce / 31 Tons Potato Chips Volume 1 Drop Vermouth / 80 Fifths Gin Area 1 ft 2 / 23 Acres Action 1 Bogey / 3,500 Golf Tournaments Quality 1 Bad Apple / 2,000 Barrels H2S - Charlie Scott 13

14 TLV = 10 ppm / 8 hr/day 10 hr workday? 10X8/10 = 8 ppm 12 hr workday? 10X8/12 = 6.6 ppm 14 hr workday? 10X8/14 = 5.7 ppm Short Term Exposure Limit (STEL) - Refers to exposures to a higher concentration than the TLV or PEL with limits placed on the time you can be exposed. STEL exposures are limited to 15 minutes followed by one (1) hour in fresh air. This cycle can be repeated four (4) times during a normal eight (8) hour work day. The STEL for H2S is 15 ppm. Permissible Exposure Limit (PEL) - The legally enforceable level as established by OSHA and is normally expressed in parts per million (PPM). The PEL is defined as the concentration that a worker may be exposed to for eight (8) hours a day, five (5) days a week for 30 years with no ill effects. The PEL for H2S is 10 ppm. Inert Gas - Gas or mixture of gases which contains only trace amounts of oxygen. Nitrogen is considered to be an inert gas. Threshold Limit Value (TLV) - A term used by the ACGIH to express the airborne concentration of a material to which nearly all persons can be exposed day after day, without adverse affects. The TLV may be expressed as a TWA (Time Weighted Average). This allows for the concentration to go up and down over the course of the work day as long as the average exposure does not exceed the TLV or PEL for the material. The TLV for H2S is 10 ppm. Threshold Limit Value / Ceiling (TLV/C) - The maximum concentration that should not be exceeded, even instantaneously, without proper protective equipment. For H2S that value is 50 ppm. H2S - Charlie Scott 14

15 Common Sources of Hydrogen Sulfide Naturally Occurring Oilfields - Drilling & Production Mines Volcanoes Geothermal Exploration Decay &Putrefaction of Organic Material Fishing Industry Breweries Municipal Sewers Slaughter Houses Animal Blood Processing Manure Processing Chemical Processes By-Product of Chemical Process Catalyst for Chemical Reaction Pulp Paper Industry Asphalt Roofing Industry Gold Ore Workers Felt Makers Miners H2S - Charlie Scott 15

16 Charlie s H2S Mantra Learn it H2S will kill you dead like a rock. You can t see it. H2S will kill you dead like a rock. You can t smell it. H2S will kill you dead like a rock. You can t taste it. H2S will kill you dead like a rock. It is heavier than air. H2S will kill you dead like a rock. Notes Notes H2S - Charlie Scott 16