Xylene leak disposal

The nature of mono-xylene

Xylene is a kind of aromatic hydrocarbon with a molecular formula of C8H10 and a relative molecular weight of 106.17. It is classified into o-xylene, p-xylene and m-xylene according to its molecular structure. The classification and mark of commonly used dangerous goods (GB 13690-92) is classified as Class 3.3 high flash point flammable liquid.

Xylene is a colorless transparent liquid with a toluene-like odor; melting point is -25.5 ° C; relative density (water = 1) 0.88; boiling point is 144.4 ° C; relative air density (air = 1) 3.66; saturated vapor pressure ( kPa) 1.33 (32 ° C); combustion heat (kj / mol) 4563.3; critical temperature 357.2 ° C; critical pressure 3.70 MPa; flash point 25 ° C; explosion range (c / o) 1.1-7.0.

Solubility: insoluble in water, soluble in most organic solvents such as ethanol, ether, chloroform.

Main use: Mainly used as solvent and used in synthetic paint coatings.

Pathways to the human body: inhalation, ingestion, absorption through the skin.

Health hazard: xylene has a stimulating effect on the eye and upper respiratory tract. At high concentrations, it has an anesthetic effect on the central nervous system. Acute poisoning: Inhalation of higher concentrations in the short term may cause obvious irritation of the eyes and upper respiratory tract, conjunctival and pharyngeal congestion, dizziness, headache, nausea, chest tightness, weakness of the limbs, confusion, and gait. In severe cases, there may be dryness, convulsions or coma. Some have rickets. Chronic effects: long-term exposure to neurasthenia syndrome, women may cause abnormal menstruation, skin dryness often occurs dry skin, chapped, dermatitis.

Characteristics of dioxane leakage accident

1, sudden strong, easy to cause a large number of people poisoning casualties. The occurrence of disasters is unexpected, and it suddenly erupts, causing harm in a short time or moment.

2. Rapid spread and large range of poisoning. After the xylene leaks, its vapor rapidly spreads around and emits outward around a central point.

3, polluting the environment, washing away difficulties. Xylene is a liquid. In addition to evaporation, it also penetrates downwards, causing serious environmental pollution and inconvenience.

4. Rescue is technical and scientific, and the task of organization and command is arduous. The basis of tactics is the development of material and tactics. Human development must be exerted on the basis of material, that is, subjective and objective, and the organic combination of people and equipment.

Third, the first power mobilization and on-site alert detection

After receiving the warning of xylene leakage, the fire command center should strengthen the first out according to the physical and chemical properties of xylene and the technical equipment of the fire department. The fire extinguishing agent for fighting xylene fire is: foam, carbon dioxide, dry powder, sand. In the first move, rescue vehicles, anti-chemical vehicles, decontamination vehicles, large water tankers, and foam vehicles should be mobilized. If there are conditions, dry powder cars and carbon dioxide vehicles should be mobilized at the same time.

When the situation is unknown, the first arrival force should stop at not less than 500 meters from the scene of the accident. The commander should immediately send the fire fighters together with the public security personnel to evacuate the masses within 500 meters around the accident site.

On-site inspection and investigation team, the investigation team should be composed of at least three people, two of whom are responsible for detecting the concentration, and one person will record and mark it later. The inspection team should be protected in accordance with the secondary standard, with closed chemical protective clothing, cotton electrostatic inner and outer clothes, and a positive pressure air breathing apparatus. The detection instrument can use a flammable gas detector and a toxic gas detector. Its marching formation can be advanced in the form of a rear triangle (one person in the first two) according to the characteristics of the site. Under the larger site conditions, the two players who are in the test should be within 50 meters of each other to facilitate mutual response. The team member responsible for setting the logo (usually held by the team leader) is followed. At the large xylene leakage site, there are three types of concentration and distribution detection methods: from the downwind to the wind source to the leakage source; from the crosswind direction parallel obliquely; the subregion is surrounded by all directions. When the flammable gas detector performs a first-level alarm (the default alarm concentration is 25c/o of the lower limit of the explosion concentration), the set card is set, and the first line composed of these marks is a mild danger zone. Then continue to push, while detecting and advancing, when the flammable gas detector performs a secondary alarm (the default alarm concentration is 50c/o of the lower limit of the explosion concentration), the flag is set to be a moderate danger zone. The lower limit of the explosive concentration exceeding the xylene is a heavy danger zone. Since the on-site detection is the instantaneous concentration of xylene. As the gas diffuses and changes in meteorological conditions, the concentration of xylene changes continuously. Therefore, after measuring the boundary of the dangerous area, 1-2 investigators should be dispatched to monitor the boundary changes in the dangerous area. Re-mark according to the changes and report to the superior in time.

Fourth, power setting and disposal measures

After the investigation is completed and the dangerous area is divided, the commander of the on-site command department should adjust the position of the vehicle personnel to make the site layout more scientific and reasonable. All vehicles and key personnel should be adjusted to the upper or side wind direction. It is very difficult to ensure that it stops at the right position in the upwind direction when the first arrival at the scene. This adjustment is necessary. The alert personnel should be outside the light danger zone, and the number of alert personnel should meet the needs of the site. A decontamination tent is set up outside the border of the lightly dangerous area, and all personnel and equipment coming out of the danger zone are decontaminated and registered by a special person.

The already leaked xylene is flooded with sand or covered with foam. All vehicles entering and leaving the danger zone wear a fire-proof cap on the exhaust pipe and the driver wears personal protective equipment that meets the secondary protection standard. Take effective measures to prevent xylene from flowing into narrow spaces such as sewers to prevent xylene vapor from mixing and exploding in a small space.

After taking protective measures, you must start to stop the leak. The leakage of xylene depends on the location of the leak. The applicable methods of plugging are as follows:

1, adjust the gap method

The adjustment gap method mainly includes a closing method, a fastening method, a positioning method, and an operating condition changing method. The closing method is to close the body and the material leakage in the pipeline is closed. The fastening method is a phenomenon in which the pre-tightening force of the sealing member is small and penetrates, and a method of increasing the pre-tightening force of the pre-tightening force of the sealing member, such as tightening the flange screw, further pressing the sealing surface of the gasket, the packing or the valve. The positioning method is to adjust the relative position of the components, such as adjusting the gap and position of the flange and mechanical seal.

2, mechanical plugging

Mechanical plugging is a method of using the mechanical deformation force of the sealing layer to force the plugging, mainly including the clamp method, the wedge method, the upper cover method and the expansion method. The clamp method is a method of plugging a metal clip band and a gasket. The wedge method is a method of using a tough metal, wood, plastic or the like to squeeze into a leak hole, a crack, or a hole to stop the leak. The upper cover method is a method of covering the entire leak portion with a cover of a metal or non-metal material to stop the leak. The expansion method is a method of using a plugging tool to flow into the pipeline with the fluid, and to expand and leak at the internal leak. The Shijiazhuang Special Service Team used the plug wedge method when plugging the xylene tank truck.

3, air cushion plugging method

The air cushion plugging method is a method in which an air cushion or an air bag fixed at a leak port is used to press the leak port by inflation, and mainly includes an air cushion outer plugging method, an air cushion inner plugging method, and a wedge air cushion plugging method.

4, glue plug sealing method

The glue plug sealing method is a method for forming a sealing layer by using a sealant at a leak port, and mainly comprises an inner coating method, an outer coating method and a strong pressure injection method. The internal coating method is to use a sealing machine to enter the inside of the equipment or the pipe, and automatically spray the sealant at the leak to stop the leak. The overcoating method is a method of applying a sealant from the outside of the device to a crack or a hole to stop the leak. The strong pressure injection method is a method in which a sealing cavity is pre-made at the leaking place, and the sealant is strongly injected into the sealed cavity body to form a sealing layer after solidification to block the leak. In addition, the use of Oriental gelatin produced by the Connaught Group also has a good effect.

5, magnetic pressure plugging

The magnetic pressure method is a method of using a strong magnetic force of a magnet to press a gasket or a sealant against a leak port of a device to block a leak, and is suitable for a flat surface at a leak, a low internal pressure of the device, and a leak hole due to trachoma and slag inclusion. Leakage of the leak.

After the plugging is completed, the next step should be to pour the can. We cannot allow xylene to continue to be stored in the accident container. When the cans are transferred to xylene, the vehicle used must be equipped with a fire-proof cap on the exhaust pipe to avoid direct contact with the metal tool. When taking the tanking measures, it is necessary to discuss and study with the unit technicians. Under the premise of confirming safety and effectiveness, the firefighters shall be responsible for the protection by the spray guns and foam guns. The commander must be clear about the operating procedures of the pouring, and finally eliminate the hidden dangers by pouring liquid. At present, there are hydraulic pump external pressure pouring and hydrocarbon pump pouring. The hydrocarbon pump is used for liquid pouring. It does not require preparation time, and the liquid pouring is fast and the time is short. When the external pressure of the compressor is used, the effect is slow, the time is long, and the danger is increased. When the tank or container wall leaks and cannot be blocked, the xylene can be introduced into other containers or stored by means of manual (diaphragm suction pump, toxic substance sealing barrel, toxic liquid suction pump, toxic liquid collection bag). tank.

Fifth, after treatment

After the leakage treatment is completed, the site should be inspected. After the inspection is fully met, the project will be handed over to the relevant department. If necessary, the xylene residue can be incinerated.

Thoroughly dismantle all personnel and equipment entering the danger zone. The scope of decontamination includes combatants, the masses, medical personnel, air, ground, buildings, water sources, equipment, and clothing. For those who have symptoms, they should be treated with decontamination. The skin is exposed to xylene, the contaminated clothing is removed, and the skin is thoroughly rinsed with soapy water and water. Eye contact with xylene, lift eyelids, rinse with running water or saline. Inhaled xylene, quickly get out of the scene to fresh air, keep the airway open, such as breathing difficulties, give oxygen, such as breathing stop, immediately artificial respiration, seek medical attention.

Six, matters needing attention

1. Choose the best route to drive and safely and quickly reach the scene of the spill.

2. The person records the cylinder pressure of the air breathing apparatus, enters the name and time of the personnel, and checks the equipment and equipment of the reconnaissance personnel.

3. Whether it is necessary to use a spray gun cover when transferring items, depending on the situation on the spot.

4. To conduct health follow-up inspections for personnel in heavy-duty areas.

5. Don't forget the decontamination of medical personnel and mutual rescuers.

6. After the accident is disposed, the accident site shall be thoroughly inspected and tested, and the relevant matters shall be confessed to the accident unit, and the on-site handover procedures shall be handled, and a certain guardian force shall be retained if necessary.