[Fire Breakdown] Limited Space Accident Rescue Technology

Abstract: The 2006--34 from improper confined space rescue incidents in 2010 State Administration of Work Safety briefing statistical results showed that reactor is confined space rescue improper accident-prone places, a total of 10 cases, accounting for 22.73%; secondary accidents caused by improper rescue the number of deaths caused by rescue workers is about 2.10 times the first accident fatalities; the main cause of casualties rescue poisoning, suffocation 33, accounting for 97.06%. Based on the characteristics of confined space accidents and the difficulties in rescue, a contingency space accident rescue technique and tactics were proposed.

Keywords : restricted space ; rescue ; tactics

0 Introduction

2006--2010 years, the State Administration of Work Safety reported on a total of 44 accidents resulting from improper rescue casualties enlarged, 44 accidents, 34 from the reaction vessel, mines, pipelines and other enclosed or semi-enclosed, underground or semi Underground restricted space accounts for 75.00% of improper rescue accidents . August 11, 2011, a city a elderly fall into the pit, four firefighters have deep pit rescue, pit due to hydrogen sulfide (H2S) high concentrations, 4 per capita poisoning. It can be seen that the rescue of confined space accidents is highly dangerous and difficult, and improper rescue can not only reduce the casualties of trapped persons, but can easily result in personal injury or death of rescue workers.

1 The characteristics of improper rescue of restricted space

1.1 Restricted space rescue accident accidents

Rescue of improper rescue space in the limited space is mainly composed of 10 reactors , accounting for 22.73%; 8 mines , accounting for 18.18%; 6 pipelines , accounting for 13.64%; 5 sewage wells , accounting for 11.36%; 5 sewage pools , accounting for 11.36% .

1.2 Distress and Rescue Workers' Casualties in Miscarriage due to Restricted Space Rescue

In the limited space rescue misuse accident, the number of persons in distress in an accident was 45. In the rescue process, 42 people were injured and 3 were injured . The rescue workers killed 88 people and injured 32 people. The average number of persons in distress accidents per constrained space rescue was 1.32 , but the average number of accidents caused by improper rescue was 2.59 deaths and 0.94 injuries per accident , that is, the deaths of rescue workers. The number is 2.10 times that of an accident . From the perspective of rescue effectiveness, the rescue cost of 88 rescue workers dead and 32 injured were exchanged for the effect of 42 dead and 3 injured in distress . The rescue input and rescue effect were obviously out of proportion and the cost of rescue was high.

1.3 Direct Causes of Distress in Rescue of Rescue of Restricted Space and Rescue Workers

The direct cause of casualties caused by improper rescue of restricted space is shown in Table 1 .

Table 1 Direct causes of casualties caused by improper rescue of confined spaces

Visible, confined space rescue improper accidents are the most frequent poisoning, suffocation, poisoning 20, accounting for 58.82%; 13 cases of suffocation, accounting for 38.24%. This is mainly due to the small space in the confined space, poor natural ventilation, and the accumulation of toxic and harmful gases such as hydrogen sulfide, methane (CH4) , and carbon dioxide (CO2) . It is not easy to spread, and people are prone to poisoning and suffocation after entering. The most dangerous is the explosion. This is mainly due to the sudden burst of explosiveness, large destructive power, and easy to cause casualties.

1.4 Restricted space rescue accident accident site hazardous substances

See Table 2 for hazardous substances on the site of improper rescue of restricted space .

Table 2 Hazardous materials on site due to improper rescue of restricted space

It can be seen that the direct cause of casualties caused by improper rescue of confined spaces is poisoning and suffocation, and the gases that cause poisoning and suffocation are hydrogen sulfide and methane, respectively. This is mainly because reactors, mines, pipelines, sewage wells, sewage pools and other places themselves contain a large number of toxic and harmful gases, and these sites are conducive to the formation of toxic and harmful gases.

1.5 The characteristics of the time when the improper rescue of confined space occurs

Constrained space rescue accidents were mostly concentrated in May , June and July , a total of 20 cases, accounting for 58.82% of 34 restricted space rescue accidents . Of the 20 accidents, 19 toxic and hazardous gases ( mainly hydrogen sulfide and methane ) on site were produced by natural decomposition. From the formation mechanism of hydrogen sulfide and methane , the temperatures in May , June and July are high, which is beneficial to Hydrogen sulfide, methane and other toxic gases are formed.

2 accident confined space rescue difficulty

2.1 Poisonous and harmful gases are more dangerous

Confined space is often closed or semi-closed, underground or semi-subterranean state, poor ventilation, high concentrations of toxic and harmful gases, easy to cause poisoning, suffocation. Common toxic and harmful gases and hazards in confined spaces are as follows :

(1) Hydrogen sulfide : Inhalation of high concentrations of hydrogen sulfide ( above 700 mg/m3 ) , death within 0.5 - 1 h .

(2) Methane : When the concentration reaches 25% - 30% , it can cause headache, dizziness, and fatigue. If it is not removed in time, it can suffocate.

(3) Carbon monoxide: air containing 0.2% CO.'s, respiratory 2 - 3min after unconscious people will die quickly when the content of 0.4%.

(4) Ammonia : Alkaline irritation and corrosive effects on mucous membranes and skin can cause tissue necrosis. Exposure to concentrations of 3500 - 7000 mg/m3 will immediately result in death.

2.2 Visibility is low, the line of sight is unclear

The low visibility and unclear sight in reaction vessels, mines, sewage wells, pipelines and other confined spaces have seriously affected the deployment of rescue operations. Rescue under a lamp portable explosion-proof strong light irradiation September 26, 2009, a city five workers were trapped in the repair of water pipes DN1200 source riverside soap tank water companies in the pipeline, on-site firefighters luminous flux of greater than 1600Lm However, visibility is also very limited. It is difficult to observe clearly the trapped people and their surroundings and can only fumble with the rescue [ 8 ]. In addition, low visibility can cause rescue workers to be nervous and panic to varying degrees, affecting the application of rescue techniques.

2.3 The situation is unfamiliar and affects the relevance of rescue operations

Reactors, mines, pipelines, sewage wells and other confined space layouts are usually complex. Rescue workers generally do not design, construct and construct drawings, and are not familiar with their distribution, layout, orientation, use, etc., and are difficult to determine the location of rescue entrances and personnel trapped. , affecting the targeted nature of the rescue operation. For example, the distance between the two exits of underground pipelines is as long as 1Km , and the trend is S -shaped, horse-rail-shaped, curved, and other irregular layouts. After the accident, rescue workers must promptly rush to the scene and start rescue immediately. The targeted rescue operations are affected. Great restrictions.

2.4 Many unfavorable factors make rescue difficult

First, in a confined space, reactors, pipelines, sewage wells, etc., have small diameters and small space, and rescue operations are usually narrow. If the diameter of the pipeline is usually about 1000mm , rescue workers can only bend and crawl within the pipeline, and only half of them can carry out rescue operations within the pipeline. It is difficult to carry out operations and physical exertion is heavy. Second, there may be accumulated water and silt in the sewage wells and cesspools, causing inconvenience to rescue workers and increasing the difficulty of rescue. Finally, some of the confined space may increase as the distance increases, and the function of communication devices decreases, affecting the coordination among rescue workers.

3 Self-rescue and mutual rescue measures for confined space accidents

In the limited space accident, when the operator is trapped, the same person and surrounding personnel are often the first to be discovered. This is also the golden time for rescue. Self-rescue and mutual rescue can effectively avoid the death and injury of trapped persons.

3.1 Self-rescue and mutual rescue procedures for confined space accidents

3.1.1 Assessing rescue missions and rescue capabilities

For self-rescue and mutual rescue, first assess the status of toxic and harmful gases in the confined space and their own rescue capabilities. The assessment of toxic and hazardous gas conditions is mainly through the following approaches :

(1) Judging the concentration of toxic and harmful gases based on the length of time the trapped person enters the confined space. If the time is very short, that is trapped, it means that the concentration is high and it is not appropriate to rescue without protection.

(2) Detect gas name and concentration with toxic and harmful gas detector. Assessment of their rescue capabilities are mainly: the number of people trapped in a confined space, location, poisonous gas type and concentration and is equipped with protective equipment, to assess whether on their own to complete the rescue mission.

3.1.2 timely alarm for help

According to the assessment results of the types and concentrations of toxic and harmful gases in the confined space, the number and location of the trapped persons and their own rescue capabilities, if they can complete the rescue mission, they will be rescued in time. If not, they should promptly report to the 110 , 119 command center or other professional rescue. Strength alarm for help, and then carry out rescue according to their own rescue capabilities.

3.1.3 do a good job of protection and help

The concentration of toxic and harmful gases in the confined space is relatively low. When the harm to the personnel is small, the self-rescue and mutual rescue can be carried out with simple protection. The simple protective equipment can be wet towel, mask, filter-type gas mask, etc. When the concentration of gases such as methane and ammonia is low, these protective equipment can also ensure the safety of rescue workers. However, if the concentration of poisonous and harmful gases is high and the oxygen concentration is low, it is not rash to rescue them, and you should wait for professional team assistance.

Gas mask

3.2 Constrained Space Accident Self-rescue, mutual rescue precautions

3.2.1 Avoid Blindness of Rescue

The main reason for the improper rescue of confined space is the blind rescue. When rescue, only the trapped persons are considered to be rescued, and the basic procedures for rescue and the safety precautions to be taken are neglected. As a result, trapped persons are not rescued. Instead, it caused its own casualties.

3.2.2 Avoid eagerness for success

Just as a surviving rescue worker in a rescue accident in a limited space rescue accident said : “I know that someone is trapped and just wants to pull him out as soon as possible.” The psychological scurry of the rescue staff is anxious and results in distorted rescue actions. Cause secondary accidents.

4 Restricted space accident professional rescue techniques and tactics

4.1 mobilize rescue forces and start the emergency rescue joint logistics mechanism

In the limited-space accident rescue, the command center ( now 110 , 119 , and 120 units in most counties and cities throughout the country ) receives an alarm and should immediately complete the first-level start-up and mobilize public security, firefighting, and 120 emergency services. On-site rescue. Restricted space accident rescue forces, in addition to a level of starting power, generally require the following forces.

4.1.1 Management and Use Department

The management and use departments are more familiar with the situation of confined spaces. In the rescue, rescue workers should promptly inform the management and use departments of the number, location, and time of personnel trapped, the limited space distribution, orientation, and functions. Rescues people who are trapped near the entrance.

4.1.2 Construction Enterprises

The use of high-power equipment, such as demolition and excavation, and excavation, is highly used in confined space accident rescue, which is conducive to improving rescue efficiency. However, emergency rescue forces such as public security and fire fighting do not have such high-power equipment. These equipments are mostly owned by construction companies. Construction companies are not government departments and do not have statutory rescue obligations. From the perspective of rescue practice, many times they are unable to participate in the rescue in a timely manner, or because they are inadequately prepared, they cannot be qualified for rescue work after they arrive. In this regard, the government should incorporate building construction companies into government emergency rescue linkage units to prepare for rescue. After participating in the rescue, the people’s government or the accident-producing agency will provide certain compensation.

4.2 Doing personal protection to ensure your own safety

The direct cause of casualties caused by improper rescue of confined spaces was mainly poisoning and asphyxiation, totaling 33 cases, accounting for 97.06% . It can be seen that the biggest risk that rescue workers face when confined space accidents are rescued is poisoning and suffocation. The rescue concept pursued by international aid is to rescue people without injuring rescue workers. The rescue personnel can save more people by their own safety.

To prevent rescue personnel poisoning, suffocation, rescuers should be prepared Respiratory protection: respirator air pressure must be checked before the situation first, confined space entry and rescue, air respirator use time normally can be 1L / 10min estimates, in order to assess Can an air respirator meet rescue needs? Second, if the restricted space has a large work surface and the conditions for carrying more cylinders, rescue workers should carry multiple cylinders at the same time so that they can be replaced in time during the rescue process. [ 7 ] Third, rescue workers entering a confined space should bring a rescuer to ensure timely assistance in case of danger.

Air breathing apparatus

4.3 Investigation Situation, Determining Countermeasures

4.3.1 The main situation of investigation

In the case of restricted-space accident rescue, the following conditions may be ascertained by inquiring alarmists, insiders, and other workers . The first is the number, location, time, and living conditions of persons trapped ; the other is the diameter of confined spaces. , material, orientation, layout, function, etc .; third is the concentration of oxygen, the name and concentration of toxic and harmful gases within the confined space. According to the situation of investigating the situation, judge the survival status of the trapped person and the time limit that can be tolerated, and determine the rescue strategy.

4.3.2 Rescue Countermeasures

Responsible measures for confined space accidents are : First, direct rescue. When a trapped person is not far from the entrance to the confined space, the rescue personnel can directly rescue the trapped person under the premise of personal protection. The second is breaking and saving people. If the trapped people are far away from the entrance and cannot directly rescue, they should choose a place that is closer to the trapped person and easier to open and open, and then open the rescue channel, and then implement the rescue. The third is to save people. The trapped personnel were rescued by group rotation and relay transportation. In short, rescue workers should weigh the advantages and disadvantages according to various aspects of the scene, and take targeted one or more rescue strategies. For example, during a pipeline accident rescue, there were five trapped people. The firefighters rescued the first trapped person for 31 minutes ( 40 minutes from the accident ) . At this rate, the rescue of the fifth trapped person would be 165 minutes after the accident. . In this regard, rescue personnel should realize that the farther the distance is, the greater the difficulty, and the longer the time spent, the other means and measures should be taken to rescue them at the same time. Otherwise, it is highly probable that a trapped person will be injured or killed.

4.4 Delivery of fresh air to ensure the safety of trapped people

In limited-space accident rescue, trapped persons are far from the entrance and are trapped for a long time. When it is difficult to rescue them, they should try to transport fresh air into confined spaces to dilute poisonous and harmful gases to provide safety for trapped persons. Even some trapped people can escape on their own as long as they have fresh air.

Common methods for delivering fresh air are : First, direct delivery. The air is directly supplied by the mobile gas supply source ( current supply distance of the mobile gas supply provided by the fire fighting team is approximately 110m ) , and the high-power air supply device can also be set to ensure long-distance air transportation. The second is the indirect delivery method. If trapped persons are far away from the entrance and exceed the limit of the supply of gas from the mobile gas source, they should be demolished first and then the air should be transported. Third, rescue workers carry air respirators, breathing bags, etc. for trapped personnel to breathe.

In addition, there may be accumulated water and silt in the confined space. After trapped persons become unconscious, the mouth and nose may be pressed on the ground, or even in water or mud. Rescue workers should give priority to ensuring smooth breathing and rescue.

4.5 Control the number and time of rescue workers to avoid their own casualties

Confined space accident rescue can easily cause rescue workers to suffer casualties. The principle of “two small ones and one small one” should be implemented during rescue. First, the number of rescue workers is small. Confined space work surface usually small, rescue groups to 3 is appropriate, rescue 2 people, with one person, and people should have a 3 cadres. The second is less time for rescue. Restricted space accidents are highly risky and physically demanding. Rescue workers should not continuously work for a long time, and personnel rotation should be done. Third, rescue workers must be leaner. Restricted space accident rescue missions should be completed by experienced rescue workers. Fourth, rescue workers are of small size. The limited space with small work surface, small size, and good strength rescue personnel is more conducive to the completion of the rescue mission.

5 Conclusion

In the case of restricted space accident rescue, rescue personnel shall, based on the situation of restricted space distribution, direction, materials, use, types and concentrations of toxic and harmful gases, combine the actual number of trapped persons, time, and location, and give full play to personnel, technology, and equipment. Function, flexible application of rescue techniques and tactics, minimizing the casualties of trapped persons and ensuring their own safety.

This article comes from "China Safety Production Science and Technology" 2013 Vol. 9, No. 5.