【Daily Question】1.15 Multiple-choice question: At what concentration of H2S can it be fatal? .
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This post was last edited by Catalyzing a Grain on 2016-1-22 at 10:49. A H2S concentration of (A) can be fatal. . A、＞760mg/m3 B、＞700mg/m3 C、＞800mg/m3 D、＞720mg/m3. Participating earns +2 wealth points; correct answers earn +5 wealth points. In-depth discussions earn +8 wealth points. Activities: “My Most Crazy” earns +20 wealth points, while the “HaiChuan Thanksgiving Season” activity earns +30 wealth points. [Petroleum chemicals related activity] Registration for “My Most Crazy” activity: http://bbs.hcbbs.com/thread-1487895-1-1.html (Source: HaiChuan Chemicals Forum). Year-end event – “HaiChuan Thanksgiving Season” [Petroleum and chemical industry section]: Everyone who participates can win surprises and big prizes. http://bbs.hcbbs.com/thread-1532394-1-1.html (Source: HaiChuan Chemicals Forum)
When the H2S concentration is (B), it can be fatal to humans. A. >760 mg/m³ B. >700 mg/m³ C. >800 mg/m³ D. >720 mg/m³
Concentration (ppm) | Effects
---|---
1000–2000 | Death within a short period of time
600 | Death within one hour
200–300 | Acute poisoning within one hour
100–200 | Loss of smell sensation
50–100 | Irritation of the trachea and conjunctivitis
0.41 | Unpleasant odor can be detected
0.00041 | People begin to detect the foul smell
Dangerous areas:
1. Extremely dangerous areas
The maximum permissible concentration of hydrogen sulfide in air is 10 mg/m³. When the concentration is ≥760 mg/m³ (502 ppm), people can rapidly suffer from acute poisoning, leading to respiratory paralysis and death. This area is considered extremely hazardous; it may be found near the following equipment: sulfur recovery units, wastewater strippers, flare systems, areas along acidic gas pipelines, gas and gas-treatment desulfurization flare tanks, as well as the first and second stages of gas-treatment desulfurization. To enter the aforementioned area, a workshop permit is required, as well as accompaniment by a supervisor; one must wear a positive-pressure self-contained breathing apparatus and use a portable hydrogen sulfide detection alarm. 2. Highly hazardous areas: When the hydrogen sulfide concentration is between 300–760 mg/m3 (198–502 ppm), it can cause pulmonary edema, bronchitis and pneumonia, as well as headaches, dizziness, nausea, vomiting, and difficulty urinating. This area is a high-hazard zone and may be found near the following equipment: water drainage from distillation units, normal pressure overhead, reduced pressure overhead, and light hydrocarbon recovery reflux drums; liquid discharge from desulfurization tanks; acidic water from the top of the debutanizer in the light hydrocarbon recovery unit; dry gas pipelines within the light hydrocarbon recovery unit; areas along the flare line; gas tanks; locations within 2 meters of gas pipelines; acidic water tanks used in catalytic and hydroprocessing processes; catalytic fractionation sections, stabilization sections, desulfurization sections, and compressors; as well as waste gasoline tanks numbered 641 and 642. To enter the aforementioned area, a workshop permit is required, as well as accompaniment by a supervisor; one must wear a positive-pressure self-contained breathing apparatus and use a portable hydrogen sulfide detection alarm. 3. Moderate hazard area: When the hydrogen sulfide concentration is between 10 mg/m3 and 300 mg/m3 (6.6–198 ppm), acute eye irritation symptoms can occur, and prolonged exposure can lead to pulmonary edema. This area is considered a high-risk zone and may be found near the following installations: the liquid sulfur storage and shaping units of sulfur processing plants, sewage treatment facilities, as well as the electrodesalination water separation units and sewage tanks in distillation plants. To enter the aforementioned area, a workshop permit is required, as well as accompaniment by a supervisor; one must wear a positive-pressure self-contained breathing apparatus and use a portable hydrogen sulfide detection alarm. Symptoms of poisoning: 1. Mild poisoning is characterized by symptoms such as photophobia, tearing, eye irritation, a feeling of foreign bodies in the eyes, runny nose, and a burning sensation in the nose and throat, along with dizziness, headache, and fatigue. Symptoms of hydrogen sulfide poisoning. 2. Moderate poisoning: Symptoms such as dizziness, headache, fatigue, nausea, vomiting, unsteady gait, coughing, difficulty breathing, itchy throat, a feeling of chest tightness, and impaired consciousness appear immediately. Eye irritation symptoms are severe, including tearing, photophobia, and stinging pain in the eyes. 3. Severe poisoning: It is characterized by dizziness, palpitations, difficulty breathing, and slowness of movement; subsequently, irritability, confusion, vomiting, diarrhea, abdominal pain, and convulsions occur. The patient quickly falls into a coma, with pulmonary edema and cerebral edema developing, and death may ultimately result from respiratory paralysis. 4. Extremely severe poisoning: Inhalation of just 1–2 breaths causes the victim to suddenly collapse; respiration ceases instantly, resulting in “electrocution-like” death. First aid for poisoning: In the event of a hydrogen sulfide poisoning incident or leak, personnel in the contaminated area should promptly evacuate to the upwind side. They must immediately call for help or report the situation; under no circumstances should they attempt to handle it on their own. First aid for hydrogen sulfide poisoning: When someone is poisoned and unconscious, rescuers must do the following: 1. Wear a gas mask or air respirator, put on protective clothing, have at least two people to assist them, enter the scene from the upwind side, and cut off the source of the leak. 2. When entering accident sites such as towers, containers, and sewers, it is also necessary to wear a safety belt. In case of an issue, evacuate the site immediately using the designated signal. 3. Ensure proper ventilation to accelerate diffusion, and use misted water to dilute and dissolve hydrogen sulfide. 4. Transfer the injured to an area with fresh air upwind as soon as possible, remove contaminated clothing, keep the airways unobstructed, and administer oxygen immediately. 5. Observe the injured person’s breathing and level of consciousness; if heartbeat and breathing have stopped, CPR should be performed as soon as possible within 4 minutes (do not use mouth-to-mouth resuscitation). 6. Cardiopulmonary resuscitation must not be interrupted until arrival at the hospital and resuscitation begins. Preventive measures 1. Production equipment that generates hydrogen sulfide should be kept as airtight as possible, and automatic alarm systems should be installed. 2. Wastewater, waste gas, and waste residues containing hydrogen sulfide must be purified to meet the emission standards before they can be discharged. 3. When entering enclosed spaces, pits, kilns, ditches, or other work areas where hydrogen sulfide may be present, one must first measure the concentration of hydrogen sulfide in the air there. Ventilation and decontamination measures should be taken, and operations may proceed only after safety has been confirmed. 4. The hydrogen sulfide concentration in the air of the working environment where hydrogen sulfide is handled must be measured regularly. 5. Take proper personal protective measures during operation; wear a gas mask, and workers should have a rescue belt or rope tied around their waists. To ensure mutual protection, at least two people must be present, and in the event of any abnormal situation, the poisoned person should be rescued immediately. 6. Persons suffering from hepatitis, kidney disease, or tracheitis shall not engage in work involving exposure to hydrogen sulfide. 7. Strengthen training for employees on relevant professional knowledge to enhance their awareness of self-protection. Precautions for various industries
1. Precautions for sampling operations
(1) Check whether the sampler is in good condition ； (2) Wear a suitable gas mask, stand on the upwind side, and have a dedicated person supervise ； (3) During sampling, the manual valve should be opened slowly; do not strike the valve with a wrench. 2. Precautions for water cutting operations
(1) Wear a suitable gas mask; have a dedicated person supervise the operation, and stand on the upwind side ； (2) There should be a certain distance between the dehydration cut and the dehydration outlet ； (3) The acidic gases that escape must be neutralized using calcium hydroxide or sodium hydroxide solutions, and isolation measures must be in place to prevent pedestrians passing by from being poisoned ； (4) During the dehydration process, no one should leave the site to prevent the release of large amounts of acidic gas. 3. Maintenance work inside equipment To carry out maintenance within equipment or containers, it is generally necessary to first purge and replace the air inside, install blind flanges, conduct sampling and analysis to ensure satisfactory results, and obtain a safety permit before proceeding with the work. However, for some equipment vessels, it is necessary to enter them prior to maintenance in order to remove residual sludge and debris. During this cleaning process, toxic and harmful gases such as hydrogen sulfide and hydrocarbon vapors are released; therefore, appropriate safety measures must be taken. The following seven items are the steps for maintenance work inside the equipment: (1) Develop a construction plan ； (2) The operators have received safety and technical training ； (3) Wear the appropriate gas mask and carry a safety belt (rope) ； (4) Sampling and analysis must be carried out before entering the equipment container for work ； (5) The duration of the exercise should not be too long; it generally should not exceed 30 minutes ； (6) Issue safety work permits ； (7) The construction process must be supervised by a dedicated person, and medical personnel should be present if necessary. 4. Working in sewers (wells) and gutters (1) Comply with the safety regulations for working in confined spaces ； (2) Control the dewatering and solid separation of various materials to prevent them from entering the sewer system ； (3) Use forced ventilation or natural ventilation to ensure an oxygen content of over 20% ； (4) Wear a gas mask ； (5) Wear your safety belt (rope) properly ； (6) Issue safety work permits ； (7) When working inside the sewer access shaft, a dedicated person must be assigned to supervise, and close communication must be maintained with those on the ground. 5. Oil tank cleaning operations (1) Before cleaning the oil tank, it is necessary to pump out the dirty oil and wastewater, and then rinse and displace them with high-pressure water ； (2) Sampling and analysis: Determine the construction plan and safety measures based on the test results ； (3) Wear the appropriate gas mask, be under the supervision of a dedicated person, and carry a safety belt (rope) if necessary ； (4) Obtain the permit for confined space work. 6. Leak sealing, disassembly, or installation operations When carrying out leak sealing, disassembly, or installation operations on equipment, containers, or pipelines that contain hydrogen sulfide, the following must be ensured: (1) Pressure operations must be strictly controlled; the valves connected to such equipment and containers should be closed, and any remaining pressure must be removed ； (2) Wear a suitable gas mask; supervision by a dedicated person is required ； (3) When removing the flange screws, do not fully loosen them before loosening begins, to prevent a large release of toxic gases. 7. Precautions for inspecting production equipment
(1) Operate smoothly; strictly prevent any leakage, spillage, dripping, or seepage ； (2) Install a fixed hydrogen sulfide alarm inside the device ； (3) Strengthen the maintenance and management of pump equipment to reduce leaks ； (4) Improve ventilation in areas where there are leaks ； (5) Containers, pipelines, valves, etc. containing hydrogen sulfide-containing materials should be regularly inspected and replaced ； (6) If a high hydrogen sulfide concentration is detected, it is necessary to report first and take appropriate protective measures before entering the site for inspection and handling. 8. Inspection tasks for oil tanks (1) It is strictly prohibited to carry out manual measurements, temperature checks, or the removal and installation of safety accessories during oil intake, output, and blending processes ； (2) For necessary inspections and dehydration, operators should stand on the upwind side, and there must be a dedicated person monitoring the process ； (3) Prepare a suitable gas mask for emergency use. Requirements for using filter-type gas masks: When the oxygen content in the air of the work area is 20% or higher, and the hydrogen sulfide concentration is less than 10 mg/m3, a filter-type gas mask with a gray canister can be used. Precautions for using filter-type gas masks: Filter-type gas masks (1) A airtightness check should be performed before use: After putting on the mask, the user should cover the air inlet with their hand and take a deep breath; if there is no feeling of obstruction or lack of airflow, it indicates that the mask is basically airtight. (2) Proper wearing: Select the appropriate size so that the edges of the mask fit tightly against the face. Before use, tighten the screws that connect the air duct to the headgear; connect the other end to the screws on the gas filter canister, ensuring a tight fit between all components so as to maintain unobstructed airflow. It is important to remember to remove the rubber plug from the air inlet hole at the bottom of the gas filter canister in advance, otherwise suffocation accidents may occur. When in use, be careful to prevent foreign materials from blocking the ventilation holes at the bottom of the gas filter canister and the exhalation valve on the hood. (3) Emergency use: In the event of an accident and when it is not possible to leave the scene immediately, the user should hold their breath and quickly take out the hood to put it on. It can be put into use only after confirming that the edge of the hood fits tightly against the head, then exhaling forcefully all the air from the body, and conducting a simple airtightness test. Requirements for the use of air respirators: When the oxygen content in the air at the workplace is less than 20%, or when the hydrogen sulfide concentration is greater than or equal to 10 mg/m³, an isolated-type gas mask must be used. Currently, the commonly used type is the self-contained breathing apparatus (air respirator). Precautions for using air respirators: Air Respirator 1. Perform a pressure test before use: Open the cylinder valve and turn the cylinder handwheel counterclockwise by at least 2 full turns. At the same time, monitor the pressure gauge reading; the pressure in the cylinder should be no less than 28 Mpa, otherwise a cylinder filled with compressed air should be used. 2. Wear the apparatus: Fasten and adjust the shoulder straps and waist belt to keep the respirator snug against the back of the body. The pressure gauge is fixed to the shoulder strap of the air respirator, allowing one to monitor its reading at any time in order to determine the amount of air remaining in the cylinder. 3. Wear the mask: Ensure that a breathing valve has been installed on the mask. Pull the hood open and put it on your head; the straps lie flat across the head and neck without twisting. Pull the headgear over the back of the head with one hand, making sure the chin is inside the chin strap of the mask. 4. Check the mask seal: Pull the ends of the neck straps (the two straps at the bottom) toward the back of the head and fasten the neck straps. Cover the mask interface with the palm of the hand and inhale until negative pressure is created to check whether the seal between the mask and the face is good. If air leakage is detected into the mask, remove it and put it on again. If the mask still does not seal properly against the face after adjustment, replace it with a new one. Note: A tight fit between the mask’s sealing ring and the skin is essential for ensuring proper sealing; it is necessary to ensure that there are no hairs or beard strands between the rubber sealing surface and the skin. 5. When the air pressure in the cylinder drops to 5.5 MPa ± 0.5 MPa, the alarm will sound to alert the user that there is at most 16% air left in the cylinder. Once the alarm sound is heard, one should prepare to end work in the hazardous area and leave it as soon as possible.
Concentration (ppm) | Effects
---|---
1000–2000 | Death within a short period of time
600 | Death within one hour
200–300 | Acute poisoning within one hour
100–200 | Loss of smell sensation
50–100 | Irritation of the trachea and conjunctivitis
0.41 | Unpleasant odor can be detected
0.00041 | People begin to detect the foul smell
Dangerous areas:
1. Extremely dangerous areas
The maximum permissible concentration of hydrogen sulfide in air is 10 mg/m³. When the concentration is ≥760 mg/m³ (502 ppm), people can rapidly suffer from acute poisoning, leading to respiratory paralysis and death. This area is considered extremely hazardous; it may be found near the following equipment: sulfur recovery units, wastewater strippers, flare systems, areas along acidic gas pipelines, gas and gas-treatment desulfurization flare tanks, as well as the first and second stages of gas-treatment desulfurization. To enter the aforementioned area, a workshop permit is required, as well as accompaniment by a supervisor; one must wear a positive-pressure self-contained breathing apparatus and use a portable hydrogen sulfide detection alarm. 2. Highly hazardous areas: When the hydrogen sulfide concentration is between 300–760 mg/m3 (198–502 ppm), it can cause pulmonary edema, bronchitis and pneumonia, as well as headaches, dizziness, nausea, vomiting, and difficulty urinating. This area is a high-hazard zone and may be found near the following equipment: water drainage from distillation units, normal pressure overhead, reduced pressure overhead, and light hydrocarbon recovery reflux drums; liquid discharge from desulfurization tanks; acidic water from the top of the debutanizer in the light hydrocarbon recovery unit; dry gas pipelines within the light hydrocarbon recovery unit; areas along the flare line; gas tanks; locations within 2 meters of gas pipelines; acidic water tanks used in catalytic and hydroprocessing processes; catalytic fractionation sections, stabilization sections, desulfurization sections, and compressors; as well as waste gasoline tanks numbered 641 and 642. To enter the aforementioned area, a workshop permit is required, as well as accompaniment by a supervisor; one must wear a positive-pressure self-contained breathing apparatus and use a portable hydrogen sulfide detection alarm. 3. Moderate hazard area: When the hydrogen sulfide concentration is between 10 mg/m3 and 300 mg/m3 (6.6–198 ppm), acute eye irritation symptoms can occur, and prolonged exposure can lead to pulmonary edema. This area is considered a high-risk zone and may be found near the following installations: the liquid sulfur storage and shaping units of sulfur processing plants, sewage treatment facilities, as well as the electrodesalination water separation units and sewage tanks in distillation plants. To enter the aforementioned area, a workshop permit is required, as well as accompaniment by a supervisor; one must wear a positive-pressure self-contained breathing apparatus and use a portable hydrogen sulfide detection alarm. Symptoms of poisoning: 1. Mild poisoning is characterized by symptoms such as photophobia, tearing, eye irritation, a feeling of foreign bodies in the eyes, runny nose, and a burning sensation in the nose and throat, along with dizziness, headache, and fatigue. Symptoms of hydrogen sulfide poisoning. 2. Moderate poisoning: Symptoms such as dizziness, headache, fatigue, nausea, vomiting, unsteady gait, coughing, difficulty breathing, itchy throat, a feeling of chest tightness, and impaired consciousness appear immediately. Eye irritation symptoms are severe, including tearing, photophobia, and stinging pain in the eyes. 3. Severe poisoning: It is characterized by dizziness, palpitations, difficulty breathing, and slowness of movement; subsequently, irritability, confusion, vomiting, diarrhea, abdominal pain, and convulsions occur. The patient quickly falls into a coma, with pulmonary edema and cerebral edema developing, and death may ultimately result from respiratory paralysis. 4. Extremely severe poisoning: Inhalation of just 1–2 breaths causes the victim to suddenly collapse; respiration ceases instantly, resulting in “electrocution-like” death. First aid for poisoning: In the event of a hydrogen sulfide poisoning incident or leak, personnel in the contaminated area should promptly evacuate to the upwind side. They must immediately call for help or report the situation; under no circumstances should they attempt to handle it on their own. First aid for hydrogen sulfide poisoning: When someone is poisoned and unconscious, rescuers must do the following: 1. Wear a gas mask or air respirator, put on protective clothing, have at least two people to assist them, enter the scene from the upwind side, and cut off the source of the leak. 2. When entering accident sites such as towers, containers, and sewers, it is also necessary to wear a safety belt. In case of an issue, evacuate the site immediately using the designated signal. 3. Ensure proper ventilation to accelerate diffusion, and use misted water to dilute and dissolve hydrogen sulfide. 4. Transfer the injured to an area with fresh air upwind as soon as possible, remove contaminated clothing, keep the airways unobstructed, and administer oxygen immediately. 5. Observe the injured person’s breathing and level of consciousness; if heartbeat and breathing have stopped, CPR should be performed as soon as possible within 4 minutes (do not use mouth-to-mouth resuscitation). 6. Cardiopulmonary resuscitation must not be interrupted until arrival at the hospital and resuscitation begins. Preventive measures 1. Production equipment that generates hydrogen sulfide should be kept as airtight as possible, and automatic alarm systems should be installed. 2. Wastewater, waste gas, and waste residues containing hydrogen sulfide must be purified to meet the emission standards before they can be discharged. 3. When entering enclosed spaces, pits, kilns, ditches, or other work areas where hydrogen sulfide may be present, one must first measure the concentration of hydrogen sulfide in the air there. Ventilation and decontamination measures should be taken, and operations may proceed only after safety has been confirmed. 4. The hydrogen sulfide concentration in the air of the working environment where hydrogen sulfide is handled must be measured regularly. 5. Take proper personal protective measures during operation; wear a gas mask, and workers should have a rescue belt or rope tied around their waists. To ensure mutual protection, at least two people must be present, and in the event of any abnormal situation, the poisoned person should be rescued immediately. 6. Persons suffering from hepatitis, kidney disease, or tracheitis shall not engage in work involving exposure to hydrogen sulfide. 7. Strengthen training for employees on relevant professional knowledge to enhance their awareness of self-protection. Precautions for various industries
1. Precautions for sampling operations
(1) Check whether the sampler is in good condition ； (2) Wear a suitable gas mask, stand on the upwind side, and have a dedicated person supervise ； (3) During sampling, the manual valve should be opened slowly; do not strike the valve with a wrench. 2. Precautions for water cutting operations
(1) Wear a suitable gas mask; have a dedicated person supervise the operation, and stand on the upwind side ； (2) There should be a certain distance between the dehydration cut and the dehydration outlet ； (3) The acidic gases that escape must be neutralized using calcium hydroxide or sodium hydroxide solutions, and isolation measures must be in place to prevent pedestrians passing by from being poisoned ； (4) During the dehydration process, no one should leave the site to prevent the release of large amounts of acidic gas. 3. Maintenance work inside equipment To carry out maintenance within equipment or containers, it is generally necessary to first purge and replace the air inside, install blind flanges, conduct sampling and analysis to ensure satisfactory results, and obtain a safety permit before proceeding with the work. However, for some equipment vessels, it is necessary to enter them prior to maintenance in order to remove residual sludge and debris. During this cleaning process, toxic and harmful gases such as hydrogen sulfide and hydrocarbon vapors are released; therefore, appropriate safety measures must be taken. The following seven items are the steps for maintenance work inside the equipment: (1) Develop a construction plan ； (2) The operators have received safety and technical training ； (3) Wear the appropriate gas mask and carry a safety belt (rope) ； (4) Sampling and analysis must be carried out before entering the equipment container for work ； (5) The duration of the exercise should not be too long; it generally should not exceed 30 minutes ； (6) Issue safety work permits ； (7) The construction process must be supervised by a dedicated person, and medical personnel should be present if necessary. 4. Working in sewers (wells) and gutters (1) Comply with the safety regulations for working in confined spaces ； (2) Control the dewatering and solid separation of various materials to prevent them from entering the sewer system ； (3) Use forced ventilation or natural ventilation to ensure an oxygen content of over 20% ； (4) Wear a gas mask ； (5) Wear your safety belt (rope) properly ； (6) Issue safety work permits ； (7) When working inside the sewer access shaft, a dedicated person must be assigned to supervise, and close communication must be maintained with those on the ground. 5. Oil tank cleaning operations (1) Before cleaning the oil tank, it is necessary to pump out the dirty oil and wastewater, and then rinse and displace them with high-pressure water ； (2) Sampling and analysis: Determine the construction plan and safety measures based on the test results ； (3) Wear the appropriate gas mask, be under the supervision of a dedicated person, and carry a safety belt (rope) if necessary ； (4) Obtain the permit for confined space work. 6. Leak sealing, disassembly, or installation operations When carrying out leak sealing, disassembly, or installation operations on equipment, containers, or pipelines that contain hydrogen sulfide, the following must be ensured: (1) Pressure operations must be strictly controlled; the valves connected to such equipment and containers should be closed, and any remaining pressure must be removed ； (2) Wear a suitable gas mask; supervision by a dedicated person is required ； (3) When removing the flange screws, do not fully loosen them before loosening begins, to prevent a large release of toxic gases. 7. Precautions for inspecting production equipment
(1) Operate smoothly; strictly prevent any leakage, spillage, dripping, or seepage ； (2) Install a fixed hydrogen sulfide alarm inside the device ； (3) Strengthen the maintenance and management of pump equipment to reduce leaks ； (4) Improve ventilation in areas where there are leaks ； (5) Containers, pipelines, valves, etc. containing hydrogen sulfide-containing materials should be regularly inspected and replaced ； (6) If a high hydrogen sulfide concentration is detected, it is necessary to report first and take appropriate protective measures before entering the site for inspection and handling. 8. Inspection tasks for oil tanks (1) It is strictly prohibited to carry out manual measurements, temperature checks, or the removal and installation of safety accessories during oil intake, output, and blending processes ； (2) For necessary inspections and dehydration, operators should stand on the upwind side, and there must be a dedicated person monitoring the process ； (3) Prepare a suitable gas mask for emergency use. Requirements for using filter-type gas masks: When the oxygen content in the air of the work area is 20% or higher, and the hydrogen sulfide concentration is less than 10 mg/m3, a filter-type gas mask with a gray canister can be used. Precautions for using filter-type gas masks: Filter-type gas masks (1) A airtightness check should be performed before use: After putting on the mask, the user should cover the air inlet with their hand and take a deep breath; if there is no feeling of obstruction or lack of airflow, it indicates that the mask is basically airtight. (2) Proper wearing: Select the appropriate size so that the edges of the mask fit tightly against the face. Before use, tighten the screws that connect the air duct to the headgear; connect the other end to the screws on the gas filter canister, ensuring a tight fit between all components so as to maintain unobstructed airflow. It is important to remember to remove the rubber plug from the air inlet hole at the bottom of the gas filter canister in advance, otherwise suffocation accidents may occur. When in use, be careful to prevent foreign materials from blocking the ventilation holes at the bottom of the gas filter canister and the exhalation valve on the hood. (3) Emergency use: In the event of an accident and when it is not possible to leave the scene immediately, the user should hold their breath and quickly take out the hood to put it on. It can be put into use only after confirming that the edge of the hood fits tightly against the head, then exhaling forcefully all the air from the body, and conducting a simple airtightness test. Requirements for the use of air respirators: When the oxygen content in the air at the workplace is less than 20%, or when the hydrogen sulfide concentration is greater than or equal to 10 mg/m³, an isolated-type gas mask must be used. Currently, the commonly used type is the self-contained breathing apparatus (air respirator). Precautions for using air respirators: Air Respirator 1. Perform a pressure test before use: Open the cylinder valve and turn the cylinder handwheel counterclockwise by at least 2 full turns. At the same time, monitor the pressure gauge reading; the pressure in the cylinder should be no less than 28 Mpa, otherwise a cylinder filled with compressed air should be used. 2. Wear the apparatus: Fasten and adjust the shoulder straps and waist belt to keep the respirator snug against the back of the body. The pressure gauge is fixed to the shoulder strap of the air respirator, allowing one to monitor its reading at any time in order to determine the amount of air remaining in the cylinder. 3. Wear the mask: Ensure that a breathing valve has been installed on the mask. Pull the hood open and put it on your head; the straps lie flat across the head and neck without twisting. Pull the headgear over the back of the head with one hand, making sure the chin is inside the chin strap of the mask. 4. Check the mask seal: Pull the ends of the neck straps (the two straps at the bottom) toward the back of the head and fasten the neck straps. Cover the mask interface with the palm of the hand and inhale until negative pressure is created to check whether the seal between the mask and the face is good. If air leakage is detected into the mask, remove it and put it on again. If the mask still does not seal properly against the face after adjustment, replace it with a new one. Note: A tight fit between the mask’s sealing ring and the skin is essential for ensuring proper sealing; it is necessary to ensure that there are no hairs or beard strands between the rubber sealing surface and the skin. 5. When the air pressure in the cylinder drops to 5.5 MPa ± 0.5 MPa, the alarm will sound to alert the user that there is at most 16% air left in the cylinder. Once the alarm sound is heard, one should prepare to end work in the hazardous area and leave it as soon as possible.
C、＞800mg/m3.
At an H2S concentration of (A), it can be fatal. A、＞760mg/m3 B、＞700mg/m3 C、＞800mg/m3 D、＞720mg/m3
C、＞800mg/m3~~~~~~~~~~~~~~~~~
When the H2S concentration reaches (B), it can be fatal. . A、＞760mg/m3 B、＞700mg/m3 C、＞800mg/m3 D、＞720mg/m3
The H2S concentration of 764405476 can be fatal; if you want to view the hidden content of this post, please reply with A. . A、＞760mg/m3 B、＞700mg/m3 C、＞800mg/m3 D、＞720mg/m3
At an H2S concentration of (A), it can be fatal. . A、＞760mg/m3 B、＞700mg/m3 C、＞800mg/m3 D、＞720mg/m3 Hydrogen sulfide enters the body through the respiratory tract; it dissolves rapidly upon contact with moisture in the respiratory tract and combines with sodium ions to form sodium sulfide, which has a strong irritating effect on the eyes and respiratory mucosa. After being absorbed, hydrogen sulfide primarily interacts with cytochrome oxidase in the respiratory chain as well as disulfide bonds (-S-S-), affecting cellular oxidation processes and leading to tissue hypoxia. When inhaled at extremely high concentrations, it strongly stimulates the carotid sinus, reflexively causing respiratory arrest ； It can also directly paralyze the respiratory center, causing immediate asphyxiation and leading to a \"electric shock-like\" death.