A home elevator is an elevator that is only used by a single household and is not used by the public. In recent years, the sales volume of home elevators in mainland China has grown exponentially, and home elevator manufacturers have sprung up, resulting in uneven quality of home elevators. The State Administration of Market Supervision has strict regulations on the production, use and inspection of special equipment, and implements the supervision of the whole process, but the household elevator is not included in the scope of special equipment supervision.
In the annex to the announcement of the General Administration of Quality Supervision, Inspection and Quarantine on revising the "Catalogue of Special Equipment" (No. 114 of 2014), the "Catalogue of Special Equipment" gives a clear definition of special equipment for elevators, in which domestic elevators installed in non-public places and only for a single family are not included in the category of special equipment. Therefore, the government does not implement mandatory supervision and management of household elevators in accordance with the "Special Equipment Safety Law of the People's Republic of China", and its manufacturing units do not need to obtain special equipment production licenses.
It can be seen that the home elevator is not supervised because the home elevator does not belong to special equipment. In fact, in terms of its own safety, home elevators also need to be checked from the aspects of production, installation and testing.
1 The current situation of the home elevator market in mainland China
Since the beginning of the 21st century, mainland home elevators have been installed in batches, and with the construction of self-built buildings and urban villas in rural areas, the mainland has become the world's largest market for newly installed home elevators. In addition to the huge demand for home elevators brought by new self-built buildings and villas, the secondary and tertiary decoration of existing self-built buildings and villas has also generated the demand for home elevators. With the gradual aging of the population in mainland China, the installation of elevators in self-built buildings and villas has become a demand of most residents.
According to the exchange speech at the annual meeting of the Design and Manufacturing Professional Committee of the China Elevator Association held in November 2020, the annual demand for household elevators in mainland China in 2020 will be about 45,000~50,000 units, which is equivalent to the annual demand for elevators in India. According to the average price of home elevator equipment and installation of 200,000 yuan per unit, the market size of home elevators in mainland China in 2020 will be about 9 billion ~ 10 billion yuan [1-2]. According to relevant forecasts, in the next few years, the market demand for home elevators in mainland China will maintain an annual growth rate of 20%. The home elevator market is so huge that it has to attract everyone's attention.
2 Several home elevator accident cases
Due to the rapid growth of the market demand for home elevators, some small and medium-sized brands of home elevators have also quickly entered the market, some products are of poor quality, there are problems such as after-sales service and maintenance are not in place, which leads to frequent safety accidents in home elevators, which seriously affects the owner's elevator experience and safety of use, and causes a bad social impact. The following cases are home elevator accidents with a high degree of concern.
On July 16, 2020, a 68-year-old owner in Nantong City, Jiangsu Province, was trapped in a home elevator for 5 hours, and was found dying. After inspection, it is caused by the failure of the elevator's frequency conversion control system, and the home elevator is not equipped with an emergency intercom device.
On July 18, 2020, an 82-year-old mother and a 64-year-old daughter in Xi'an were trapped in the car due to a home elevator failure.
On February 14, 2021, a home elevator injury incident occurred in a community in Tianjin. The elevator suddenly shook up and down during operation, and stopped instantly, causing passengers to fall and be trapped. The staff of the maintenance unit arrived at the scene 2 hours later, and found that the trapped person had a sacrum fracture after being delivered to the hospital. Because the cause of the elevator failure is unknown, there is a dispute between the owner and the elevator company.
In recent years, home elevator accidents are not uncommon and on the rise, and most of the accidents are ultimately problems in the manufacturing, installation and maintenance of home elevators.
3 Several case studies of potential safety hazards in home elevators
When the author tested the home elevator, it was found that the products of many home elevator manufacturers were not designed in accordance with the requirements of GB/T 21739-2008 "Code for the Manufacturing and Installation of Home Elevators", and such defective design would cause many potential safety hazards. Here I list a few typical cases.
As shown in Figure 1, it is found that although a household elevator has an electrical safety device for verifying the closure of the floor door, there is no electrical safety device for verifying the lock of the floor door. GB/T 21739-2008 Article 6.5.4 requires: The locking state of the landing door shall be verified by a qualified electrical safety device. In the process of running the home elevator, if the landing door door lock is blocked or not locked, the elevator can not be detected and stopped, and then the landing door is knocked open and then causes the risk of personnel falling and shearing.
As shown in Figure 2, the distance between the inner surface of the shaft wall of a household elevator and the nearest doorway edge of the car sill is greater than 0.15m, and the car door lock is configured, and the meshing amount of the car door lock is less than 7mm. The design has two flaws. (1) GB/T 21739-2008 Article 12.1.1.1 requires that the horizontal distance between the inner surface of the hoistway and the nearest doorway edge of the car sill, car door frame or sliding door should not be greater than 0.15m. The requirement does not say that the distance is not limited after the car door is locked, so for the home elevator, the horizontal distance between the inner surface of the hoistway wall and the car sill and the nearest door edge of the car door frame should not be greater than 0.15m under any circumstances. (2) GB/T 21739-2008 Article 7.13.2.8.3 requires: If the car door needs to be locked, the design and operation of the door lock device should adopt a structure similar to that of the landing door lock device. That is, the meshing depth of the car door lock should also reach at least 7mm, so as to ensure that the car door can operate normally when the car door is firmly locked, so as to prevent the car door from being opened by passengers during operation.
As shown in Figure 3, the space size of a home elevator pit is insufficient, and the lower limit stop device is not installed. At present, most home elevator manufacturers take their own products to occupy a small space and beautiful appearance as the sales highlight to win the attention of customers, but customers do not know that there are greater safety hazards behind this "petite and beautiful" home elevator. The shallow pit design in Fig. 3 does not meet the minimum requirements for pit space in GB/T 21739-2008, and the manufacturer does not install the lower limit stop device in order to save costs. The shallow pit design itself will increase the failure rate of the elevator due to the elongation of the wire rope, and the failure to install the lower limit stop device will increase the risk factor of maintenance personnel.
As shown in Figure 4, an elevator is a machine room-less home elevator with a maintenance operation site on the top of the car, and in accordance with the requirements of Article 4.3.1 of GB/T 21739-2008, when it is necessary to repair (maintain and repair) or inspect the machine from the car roof, a mechanical locking device should be installed. When the maintenance personnel are repairing or inspecting the machine, it may cause the car to lose control or move unexpectedly, so if there is no mechanical locking device, not only the safety of the home elevator maintenance personnel can not be guaranteed, but also the home elevator car itself is easy to lose control during the maintenance process, resulting in damage to the equipment.
As shown in Figure 5, the tensioning device of a household elevator speed limiter, although a verification switch is installed, the switch is not wired due to the negligence of the installation unit. GB/T 21739-2008 Article 10.2.1.3 requires: through qualified electrical safety devices, the break or excessive elongation of the speed limiter rope shall stop the operation of the home elevator. The speed limiter is the most effective guarantee to verify the car speeding or falling, such as the speed limiter rope is broken or over-elongated without electrical safety device verification, not only the speed limiter loses its role and can not operate to stop the car, but also the disconnected speed limiter rope is involved in the relevant components and causes serious accidents.
The author also found many potential safety hazards in manufacturing and installation during the inspection process of home elevators. For example: there is no emergency alarm device in the car, the automatic rescue device is invalid, the emergency unlocking device is invalid, etc. If these hazards are not detected or addressed in a timely manner, they will pose a certain risk to passengers and maintenance personnel.
4 Measures and suggestions to ensure the safety of home elevators
To sum up, as far as the current home elevator safety situation is concerned, the production, installation and maintenance of home elevators need to be improved, and supervision should be strengthened, standards should be strictly implemented, and testing should be strengthened.
(1) Strengthen supervision. In recent years, home elevator manufacturers have sprung up, and the quality of home elevators is uneven, mainly because of the hot home elevator market, and the manufacture and installation of home elevators do not need to obtain the corresponding license. Therefore, it is recommended that the relevant departments should (1) strictly control the manufacturing and installation license of home elevators, formulate corresponding review rules, improve the comprehensive strength and personnel quality of home elevator manufacturing units and installation units, and improve the quality of their products from the source. (2) Regularly organize and implement spot checks on home elevator manufacturing and installation units, formulate penalty rules, and maintain product quality from the process. (3) Strengthen the attention to home elevator accidents, investigate the causes of accidents, combine the specific situation, cancel the license of home elevator manufacturing or installation units with serious accidents, and feedback to the front to reduce accidents.
(2) Strictly implement standards. At present, many home elevator manufacturers are based on different standards, which can be divided into three categories: GB 7588-2003 "Safety Code for Elevator Manufacturing and Installation", GB/T 21739-2008, EU Machinery Directive (2006/42/EC) or EN 81-41:2010 "Safety Code for Elevator Manufacturing and Installation Special Elevators for Carrying and Carrying Goods - Part 41: Vertical Lifting Platforms for Persons with Reduced Mobility [7]. The author believes that some of the requirements in GB 21739-2008 are more stringent than GB 7588-2003 and EN 81-41:2010, and in some respects, the danger level of home elevators is higher than that of ordinary passenger elevators, especially for home elevators without car doors. Therefore, the design of home elevators cannot copy the manufacturing standards of ordinary passenger elevators, and the manufacturing standards of home elevators should not be ignored. It is recommended that the relevant departments strictly require home elevator manufacturers to manufacture in accordance with the requirements of GB/T 21739-2008 standard to standardize manufacturing.
(3) Strengthen testing. At present, the public's attention to home elevator testing is insufficient, and some home elevator manufacturing units, installation units, maintenance units and owners even deliberately avoid testing. It is suggested that the government should publicize the necessity of home elevator testing, improve the safety awareness of the masses, advocate the masses to welcome testing for safe riding, and advocate manufacturers to welcome testing for quality certification. At the same time, it is recommended to formulate strict testing rules to standardize testing.
5 Conclusion
At present, the reason why home elevators do not belong to special equipment is that their main body is different from ordinary passenger elevators, not because the safety degree of their own structure is better than that of ordinary passenger elevators. Moreover, because there is no relevant agency to supervise the home elevator, the safety of the current home elevator is worrying. The author hopes that through the analysis in this article, the relevant departments will be promoted: strengthen the supervision of home elevators and standardize the inspection of home elevators to ensure the safe and stable operation of home elevators.
Source: China Elevator Magazine Issue 2, 2023 (Author: Wang Zhiyu, Zhang Qingpeng, Zhao Xiaojian, Bi Chenshuai / Tianjin Institute of Special Equipment Supervision and Inspection Technology)
Editor: Huang Keshu
Preliminary review: Zhou Jing
Reviewer: Gu Yan
Final review: Yang Hong
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