Precautions for transporting hydrogen sulfide gas

1. Basic properties of matter

Hydrogen sulfide (H₂S) is a highly toxic and flammable acid gas with the following key characteristics:

• Physical properties: colorless, with rotten eggs smell at low concentrations, and cannot be perceived by olfactory fatigue at high concentrations. The molecular weight is 34.08, the density is larger than that of air (1.19), and it is easy to accumulate in low-lying places.

• Chemical properties: Mixing with air can form an explosive mixture, with an explosion limit of 4.0%-46.0% (volume ratio), and a spontaneous ignition temperature of 260℃

• Toxicity: IDLH value (immediately life-threatening or health-care concentration) is 100ppm, high concentration (>1000ppm) can cause "lightning type" death

2. Regulations and Standard Requirements

Domestic regulations

• "Regulations on the Safety Management of Hazardous Chemicals" (Revised in 2013): It is clear that the transport unit must have the corresponding qualifications, and drivers and escorts must hold certificates to work

• GB 13392-2023 "Vehicle Signs for Dangerous Goods in Road Transport": Implemented on April 1, 2025, requiring vehicles to be equipped:

◦ Rectangular sign: orange background, with hazard identification number "23" (toxic gas) on the upper part and UN number "1053" on the lower part

◦ Rhombus sign: black "toxic gas" pattern, white background, size 250mm×250mm

◦ Special signboard: If the transportation temperature is ≥100℃, high-temperature substance markings must be added

International norms

• IMDG rules: The loading class during sea transportation is D (for housing area only) and must meet the isolation requirements

• ADR Convention: Vehicles must be equipped with emergency leakage treatment equipment and self-sustaining respirators during road transport

3. Transportation preparation requirements

1. Packaging and container

• Container material: Steel gas cylinders must be used (compliant with GB/T 5099 standards), and special valves must be used

• Filling limit: The filling volume of the gas cylinder must not exceed 98% of the volume, leaving room for expansion

• Marking requirements: The bottle body must be marked with "toxic gas", "flammable gas" markings and UN 1053 number

2. Vehicles and Equipment

• Vehicle qualification: You need to obtain a "Road Dangerous Goods Transport License", and tank-type vehicles need to be equipped with emergency cutoff devices

• Security configuration:

◦ Anti-static grounding device (ground resistance <10Ω)

◦ Explosion-proof ventilation systems and lighting equipment

◦ Portable hydrogen sulfide detector (range 0-1000ppm, resolution 1ppm)

◦ At least 2 sets of positive pressure air respirators (cylinder pressure ≥28MPa)

3. Personnel Qualifications

• Drivers must hold a professional qualification certificate for dangerous goods transportation, and escorts must pass the safety operation training of hydrogen sulfide

• Each vehicle is equipped with at least 2 personnel, and communication is kept unobstructed throughout the whole process (it is recommended to use explosion-proof intercom)

4. Transportation process control

1. Loading and fixing

• Loading requirements: The cylinder must be placed flat, the bottle opening is consistent, the height does not exceed the vehicle guardrail, and is fixed with triangular wood to prevent rolling.

• Isolation requirements: Keep a safe distance of at least 3 meters from oxidants and alkaline goods, and mixing is strictly prohibited.

• Route planning: Avoid densely populated areas, tunnels, and bridges, choose morning and evening transportation in summer to avoid sun exposure

2. Monitoring on the way

• Check every 2 hours:

◦ Gas cylinder valve sealing

◦ Pressure gauge readings (normal range 1.6-2.0MPa)

◦ Vehicle logo integrity

• When parking and rest, you need to select the upper wind and set a warning sign. Drivers must not stay away from the vehicle.

5. Emergency response measures

1. Leak Emergency Response

Start the third-level emergency procedure immediately:

1. Evacuation:

◦ Immediately evacuate to 150 meters above the upper wind and use a hydrogen sulfide detector to define the warning area

◦ Call 119 and 120 to report "UN 1053, Class 2.3 toxic gas leak"

2. Leak control:

◦ Small leaks: Use an alkali-soaked cotton cloth to cover the leak point (recommended 5% sodium hydroxide solution)

◦ Large-scale leakage: build a dike and spray mist water to dilute (spray rate 10L/m²·min)

3. Gas treatment:

◦ It can be absorbed through aqueous iron chloride solution (10% concentration) to produce iron sulfide precipitate

2. Poisoning first aid

• Mild poisoning (＜100ppm): Move to a fresh place in the air, inhaling oxygen, and continue to seek medical treatment.

• Severe poisoning (>500ppm): Cardiopulmonary resuscitation immediately, mouth-to-mouth artificial respiration is prohibited, and hyperbaric oxygen treatment is used

3. Fire and explosion disposal

• If combustion occurs:

◦ Low fire: Use dry powder or CO₂ fire extinguisher

◦ High fire: Use a water curtain to cool the gas cylinder, and turn off the gas source after the fire is controlled.

◦ It is prohibited to spray water directly to the leakage point to prevent freezing from blocking the safety valve

6. Accident case warning

Typical case analysis

1. 2024 Pemex Oil Refinery Spill Accident:

◦ Reason: The pressurized pipeline flange was accidentally opened during maintenance, releasing 27,000 pounds of hydrogen sulfide

◦ Consequences: 2 people died, 27,000 people were evacuated, and the direct loss exceeded 10 million US dollars

◦ Lessons: No energy isolation procedures were performed, lack of effective gas detection

2. Anhui landfill poisoning accident in 2025:

◦ Cause: The gas concentration was not detected in confined space operations, and blind rescue caused 3 deaths

◦ Lesson: Not equipped with a four-in-one gas detector, emergency training is missing

7. Transportation records and documents

• The transportation process requires full records:

◦ Departure, destination, time

◦ Hydrogen sulfide concentration monitoring data

◦ Driver and escort information

• Documents must be kept for at least 1 year for inspection by regulatory authorities

8. Emergency contact information

• National Dangerous Chemicals Emergency Hotline: 400-059-9999

• Local emergency rescue center: [Fill in the specific contact information]

• The person in charge of the transportation unit’s safety: [Fill in the specific contact information]

Important tips: Hydrogen sulfide transportation is a high-risk operation, and it is necessary to strictly implement the principle of "safety first and prevention first" and conduct emergency drills regularly (it is recommended once a quarter).