Fault barrier analysis of the most dangerous car s

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Failure barrier analysis of the danger of being sheared by the lift car

1 analysis of risk factors

there are mainly the following four forms of hazard sources in the inspection process of elevators: fall injury accident hazard source, mechanical injury accident hazard source, electrical injury 2, relaxation experimental machine installation common sense accident hazard source, other injury accident hazard sources (such as poisoning, fire and explosion accidents during the inspection in toxic, harmful and explosive places). In the process of elevator inspection, the proportion of mechanical injury accidents is also quite large. In this paper, the mechanical injury accident is analyzed, and the fault tree analysis (FTA) method is used to analyze the possible accident of being sheared by the lift car in the process of landing door inspection. Therefore, according to the actual inspection, the dangerous fault tree cut by the lift car is compiled (as shown in Figure L). The event conditions represented by the symbols in the figure are shown in table L

2 calculation of minimum cut set

the set of minimum basic events that can cause the shear event of the running car, that is, the minimum cut set. The minimum cut set indicates the danger of the system, and each minimum cut set is a possible channel for the top event to occur. The more the number of minimum cut sets, the more dangerous the system is. It can be concluded that the reason for the occurrence of events on the item must be the result of the simultaneous existence of several events in a minimum cut set. Through statistical calculation, we can find the weakest link in the system and take preventive measures

there are 9 minimum cut sets, namely {x1x4x7}

after calculation, the nine are the minimum cut sets, which means that the system has nine hazard sources. The following is a further analysis of the impact of 9 hazard sources on the occurrence of car shear events, that is, the structural importance analysis of each hazard source

3 structural importance analysis

structural importance analysis is to analyze the importance of each basic event from the fault structure, and analyze the impact of the occurrence of each basic event on the shear of the running car without considering the probability of each basic event. The safety evaluation logic analysis method is used, and its approximate calculation formula is:

in the formula, I (I) - the approximate discriminant value of the important coefficient of basic Xi

ki - all cut sets containing Xi

n - the number of basic events in the cut set where the basic event Xi is located

from the analysis results of the structural importance of the basic event, it can be seen that the important event causing the shear of the running car is that the shear accident will occur only when people are in the dangerous position of the hoistway and the car suddenly moves, that is, to prevent the failure of the electrical switch of the elevator misoperation and someone calling the elevator. And it is concluded that the structural importance coefficient is the same, that is, the occurrence of each basic event has the same impact on the shear event of the car being operated. Therefore, safety measures should be taken for the above events during inspection or maintenance to eliminate the risk of accidents

4 safety countermeasures taken

(1) check the verification and eliminate the accidents caused by elevator defects

for example, if we want to go on the car item to carry out the inspection of items in the hoistway, we must verify the reliability of door lock, emergency stop and maintenance electrical switch before going on the car item

(2) check the environmental fire

poor working environment will induce human errors, which will lead to accidents. Falling, falling from height, object strike, electric shock and other accidents often occur in poor inspection environment. Therefore, it is very important to control the inspection environment fire for inspection safety. Article 8 of elevator supervision and inspection procedures and Article 3 of gb10060 code for acceptance of elevator installation stipulate the inspection conditions and installation acceptance conditions for on-site inspection

(3) improve the inspection conditions and adopt intrinsically safe inspection methods

at present, the inspection of pit item h, such as measuring the distance between the lowest point of the car bottom and the car buffer, requires the inspector to enter the pit, and then the car descends to the leveling position of the lowest floor at the normal running speed. The inspector uses a steel tape to measure the distance between the two, which is in danger of being squeezed and sheared. Therefore, if the remote sensing technology can be adopted, it can be achieved that when the elevator is running, the inspectors can measure it without being in the pit

apply antirust oil to rusty parts

5 conclusion

due to people's limited cognitive ability, sometimes they can't fully understand the hazard sources and their harmfulness in the system. Even if they know the existing hazard sources, with the development of science and technology, the emergence of new technologies, new processes, new energy, new materials and new products will produce new hazard sources. For the known hazard sources, technology, capital It is impossible to completely eradicate the limitations of many factors such as personnel quality. Therefore, the goal of system safety is to further verify the performance of new functional materials of high thermal conductivity, electrical conductivity and corrosion-resistant copper alloy produced by Guoliang copper, control the source of danger, and minimize the possibility of serious accidents, or in case of accidents, cause casualties and property losses. In general, we should do a good job in three aspects: first, organize relevant technical experts to formulate elevator supervision and inspection rules and safety books for inspectors, and explore intrinsically safe inspection methods; Second, the inspection should be carried out in strict accordance with the inspection procedures and inspection rules to ensure that the elevator inspection process is foolproof. Third, every inspector should establish a sense of safety and self-protection, and strictly wear personal protective equipment during the inspection process

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