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Hydrogen Sulfide Gas. Describe H 2 S gas and where it is found:. Hydrogen Sulfide is a highly toxic gas often associated with operations involving decomposing organic material (rotting plant and animal tissues).
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Describe H2S gas and where it is found: Hydrogen Sulfide is a highly toxic gas often associated with operations involving decomposing organic material (rotting plant and animal tissues). Hydrogen Sulfide occurs in a variety of natural and industrial settings. It is found in large amounts in natural gas and petroleum.
H2S Video Double click mouse HERE to begin movie.
Other areas where Hydrogen Sulfide can be found are: • gas plants • refineries • petrochemical plants • pulp mills • Underground mines • sewers
H2S is commonly know by the following names: Hydrogen sulfide is a gas made up o two atoms of hydrogen and one atom of sulfur; therefore it’s chemical symbol is H2S. • Sour gas/crude • Sulfur hydride • Stink damp • Rotten-egg gas • Swamp gas
H2Sis colorless. Sometimes on cool mornings it hovers over the ground and appears to be a fog or a mist. Always remember that Hydrogen Sulfide has no color; it is clear.
Highly Toxic • Hydrogen sulfide concentrations as low as 70 PPM (Parts Per Million) (0.07% of air volume) have caused fatalities. • Concentrations above 10 PPM(0.001% of air volume are generally regarded as unhealthy for continuous exposure.
Poor Warning Characteristics • Concentrations of H2S below 100PPM have a rotten gas odor or, possibly, a sweet, acetone-like odor. • Concentrations of H2S 100PPM deaden the sense of smell and no odor is detectable. Do not use your nose to detect H2S.
Extremely Flammable • H2S has an extremely broad flammable range (4.3% - 46%) and an unusually low temperature of ignition (518º F). • When H2S burns, it forms sulfur dioxide (SO2) which is also toxic and heavier than air. • It burns with a pale blue flame, noticeable mostly at night.
Heavier than Air • Compared to air at an equal temperature, H2Sis 19% heavier. • H2Stends to settle in poorly ventilated, low-lying areas, such as pits, ditches, holds, and voids. • H2S willtravel just like water. It will eventually fill up these lower areas and displace the oxygen or it will flow back to a source of ignition and cause a fire or an explosion. This is why it is so important to stay out of the low – lying areas and stay on high ground.
Hydrogen Sulfide is readily dispersed by the wind. The ambient air will actually dilute the H2S. You should always try to stay in an upwind location during an H2Semergency. • If trapped downwind do not turn upwind and try to escape. Try and quarter the wind in order to get to the less concentrated areas of the gas. Then, turn upwind and rescue yourself. • Always use the “buddy system” when working in a known or suspected Hydrogen Sulfide environment. Remember to always keep your buddy in sight while in the danger zone.
Corrosive • H2S causes severe corrosion to copper, silver, brass and bronze. • H2S also reacts with the iron in steel to form the potentially dangerous compounds iron pyrite and iron sulfide. • H2S can also cause sulfide stress cracking in certain grades of steel that can result in the catastrophic failure of tools and equipment.
Symptoms The symptoms experienced by an individual depend upon several factors including: • concentration • length of exposure • individual susceptibility
Death from breathing H2S occurs by chemical pneumonia or by respiratory paralysis. H2S will suffocate you by attaching itself to the red blood cells in your bloodstream and prevent them from carrying oxygen to the tissues and organs of the body. As the toxic gas builds up in your bloodstream, you will find yourself breathing faster and faster. The faster you breathe, the more H2Senters your lungs. Soon, the respiratory control center in the brain will become paralyzed and will cease to function. Depending upon the concentration of the gas, this can happen in as fast as 3 minutes or less.
Alcohol consumption and H2S exposure. Alcohol consumption within 24 hours can cause this process to be quicker than normal. This is due to the oxidation process the body uses in order to rid itself of alcohol. Unfortunately, this process leaves no excess reserve for the body to fight off the effects of H2S. Do not consume alcohol within 24 hours of being exposed to Hydrogen Sulfide
OSHA Permissible Exposure Limit (PEL) In order to protect workers from possible adverse health effects, OSHA has established a Permissible Exposure Limit (PEL) of 10 PPM for H2S. Workers exposed to concentrations of H2Sgreater than 10 PPM must wear respiratory protection.
Contingency Plans At facilities where H2Sis potentially present, an emergency response plan must be developed. This emergency response plan is usually called a contingency plan. Contingency plans describe, in detail, the actions that are necessary to ensure safety in the event of an H2Srelease.
Detection and Monitoring • Because of the very poor warning characteristics of H2S, instrumentation must be used to provide warning of unsafe concentrations of the gas. • Portable detectors are used to warn individuals of the presence of H2Swhen fixed systems are not available or do not provide adequate coverage. • Fixed systems are used to continuously monitor the concentrations of H2Sin a specific location.
With fixed systems, sensors are usually located in key areas. These include: • where workers are likely to be present • where H2Sis likely to be released • where H2Sis likely to accumulate
Alarm Settings • When H2Sis detected, sensors send signals to the monitor. The monitor automatically sounds alarms at preset concentrations.
Usual Land Monitoring Settings: low alarm – 10 PPM flashing amber light high alarm – 20 PPM intermittent siren
Usual OCS Settings: • low alarm – 10 PPM • flashing amber light • high alarm – 20 PPM • intermittent siren and flashing red light • high-high – 50 PPM • continuous siren and flashing amber and red light
Protection Hydrogen Sulfide cannot be removed from the air. The is only way to protect yourself from the effects of this gas, is to remove yourself from it. This can be accomplished in one of two ways. • You can physically remove yourself from the area, if possible. • You can don (wear) a self – contained breathing apparatus (SCBA), which will provide you with a source of clean, fresh breathing air.
Personal Protective Equipment • Self-Contained Breathing Apparatus (SCBA’s) are the primary forms of personal protective equipment used to protect workers against H2Sexposure. Personnel required to work in areas with an H2Sconcentration greater than 10 PPM must wear SCBA’s. • SCBA’s must be used as per the requirements of OSHA’s Respiratory Protection Standard.
Self – Contained Breathing Apparatus (SCBA) A SCBA consists of five (5) components. These are the • cylinder • the harness • the face-piece • the breathing tube • the regulator • Regulators can be either “DEMAND” or “PRESSURE DEMAND” type. In a demand type regulator the air will only flow to the face-piece when there is a demand created for it by the user. This creates a negative pressure inside the face-piece and if the mask leaks the leak will be toward the inside. In the pressure demand mode or the positive pressure mode, the air flows constantly from the regulator to the face-piece. This allows a constant pressure inside the face-piece so that if the mask leaks the leak will be toward the outside and away from the user. Only pressure demand type regulators are allowed offshore.
Special problems in respirator use: There are several common types of breathing apparatus and it is important for the user to be trained not only in the proper use, but also, the limitations of each type of breathing apparatus. Some of the special problems encountered in respirator use are: • Facial hair – Facial hair lying between the sealing surface of the respirator face-piece and the wearer’s skin will prevent an effective seal. Even one day’s growth of stubble will permit excessive contaminate penetration and/or loss of air. • Contact lenses – Contact lenses can be worn while wearing a respirator in a contaminated atmosphere. • Corrective spectacles – Corrective spectacles with temple bars or straps that interfere with the respirator face seal should not be worn as they will permit excessive contaminant penetration. • Pyschological disturbances – Psychological disturbances, such as claustrophodia, are a definite hazard to the wearer of a respirator.
Safety Measures When approaching the jobsite, it is necessary to take the following precautions to provide safe entry: • Observe condition signs and audiovisual alarms. • Check for wind direction. • Look for personnel and their activity. • Enter the jobsite slowly.
Safety Measures Minimum of two (2) defined alternate escape routes, preferably roads. Continuous monitoring or detection equipment is required along with an adequate audiovisual warning system. Portable detectors and combustible gas meters provide additional degrees of safety. Gas ignition hazards must be eliminated and “No Smoking” regulations strictly enforced. Strategically placed explosion – proof mechanical ventilators reduce exposure risks. An H2S Awareness Training Program and regular drills are a must. Practice makes proficient. Observe wind direction indicators, such as windsocks and streamers.
Safety Measures Avoid low – lying areas since H2S is heavier than air. Make sure and use the buddy system for mutual safety. Maintain and observe warning signs. Post emergency numbers in appropriate places. Locate emergency safe briefing areas at least 250 feet from the source of the gas as practical. Know the company H2S emergency procedures.
Rescue Procedure • Rescuers must have the appropriate equipment and training. Untrained rescuers frequently die attempting to assist victims! • Quick rescue is very important in ensuring that victims who have stopped breathing sustain the least amount of injury possible. Victims in respiratory arrest have three to six minutes before they develop permanent brain damage. • Prompt rescue is only possible if the “Buddy System” is being used. The “Buddy System” is in effect when a designated person is in frequent contact with the person working in a potentially hazardous area.
Rescue Procedure: Put on (don) your full rescue unit (30 minute SCBA) before attempting a rescue, or you too will become a victim. Remove the victim to fresh air immediately. If breathing, maintain the victim at rest and administer oxygen if available. If the victim is not breathing, start artificial respiration immediately.
First aid for an unconscious H2Sexposure victim: • open the airway • look, listen, and feel for breathing • if no breathing, pinch the victim’s nostrils closed and give two slow full breaths • check for a pulse on the victim’s neck • if a pulse is present, give one breath every five seconds until the victim regains consciousness • if no pulse is present, begin CPR • People exposed to high concentrations of H2Soften vomit. They may need assistance in keeping their airway open once they regain consciousness.
Rescue Procedure: Call an ambulance and get the victim medical treatment. Keep the victim lying down with a blanket, coat, etc. under the shoulders to keep airway passage open. Conserve his body heat and do not leave him unattended. If the eyes affected, wash them thoroughly with clean water. Cold compresses may be helpful. In case the victim has only minor exposure and does not lose conscious totally, it is best if he does not return to work until the following day.
