Methods/steps
1
What kinds of lift chairs are there?
Literally, a lifting chair is a chair whose seat height can be lifted, which is generally divided into three types: pneumatic, hydraulic and mechanical. At present, pneumatic lifting chairs occupy a high share in the market. The adjustable function of the pneumatic lifting chair is realized by the gas spring parts in it.
So how does the pneumatic lifting chair realize the height adjustment function? Gas spring is a kind of elastic element which uses gas and liquid as working medium and can support, buffer, brake, adjust height and angle. It consists of a pressure pipe, a piston, a piston rod and a plurality of connectors. The working principle of pneumatic lifting chair is to press inert gas, such as nitrogen, into a closed cavity, so that the pressure in the cavity is greater than atmospheric pressure, and the piston rod moves by using the pressure difference, thus achieving the function of adjusting the chair.
Hydraulic lifting chairs are mostly used in special occasions, such as barber chairs. When using them, a third party other than the user needs to apply driving force to realize the lifting function of the chair. Hydraulic lifting mechanism is the principle of hydraulic jack. Due to the high cost, relatively complex structure and insensitive height adjustment, the hydraulic lifting chair has a low market share in China.
Besides pneumatic lifting chairs, there is also a mechanical lifting chair, that is, the chair is supported by a threaded solid steel bar. When the height of the computer chair needs to be adjusted, it is necessary to put the chair down, loosen the screw of the fixing bolt, adjust it and screw it on again.
Compared with mechanical lifting chairs, pneumatic lifting chairs have lower manufacturing cost and convenient use, so they have a larger market share. However, the safety of pneumatic lifting chairs is not as good as that of mechanical lifting chairs. In recent years, the explosion accidents of lift chairs in China are all pneumatic lift chairs.
2
What caused the explosion of pneumatic lifting chair?
Generally speaking, the following two situations may lead to explosion: first, the wall thickness of gas spring is uneven or the preloading is too large. Second, frequent height adjustment and rotation lead to overheating and explosion.
In general, this kind of pneumatic rod, similar to a bicycle pump, is filled with high-purity inert gas nitrogen. People sitting in a chair, although the pressure of nitrogen has increased, it is still within the limit range of air pressure expansion, and there will be no problems. However, some inferior pneumatic rods often have problems such as insufficient nitrogen purity and inferior material. In the case of high temperature in summer or frequent lifting of the seat, the pressure in the pneumatic rod suddenly rises, which is easy to cause explosion. In order to reduce the cost, some black manufacturers use free high-pressure air instead of inert gas, which is more likely to cause the explosion of pneumatic rods.
In addition, some consumers' mistakes in using pneumatic lifting chairs also have potential safety hazards, such as sitting too hard or frequently adjusting the lifting handle.
three
How powerful is the explosion of the lift chair?
According to the calculation, under normal circumstances, when the air pressure rod under the chair bears a person's weight, the air in the air pressure rod will be compressed, and then the air pressure inside will reach about 24 atmospheres. Once an explosion occurs, the 24 atmospheres multiplied by the bottom area of the piston in the outer tubing is the instantaneous explosion power of the pneumatic rod. This force will reach about 70 to 80 kilograms.
In the experiment, when the atmosphere is compressed to about 7 atmospheres, the air pressure is released instantly, the ejector pin in the piston is ejected, and a density board is placed not far from the front end of the ejector pin to simulate the surface of the chair. As a result, the density board about three or four millimeters thick is easily broken. In the second group of experiments, they increased the thickness of the density board and placed two density boards. As a result, the two density boards could not resist the impact of seven air pressures.
Experiments show that the force generated by 24 air pressures can penetrate at least 6 density plates, which is amazing. It is precisely because of the strong pressure that it has produced such great destructive power.
four
How to choose a safe lifting chair?
1. Buy products from regular manufacturers.
When consumers buy this kind of pneumatic lifting chair, they must choose a regular product with manufacturer information. Don't be greedy for cheap products, otherwise not only the quality can't be guaranteed, but also there may be no way to protect rights if there are problems. When purchasing, consumers should pay attention to check whether the product has a certificate of conformity, a registered trademark, the name and address of the manufacturer, etc.
2. Carefully choose chairs that are too cheap.
According to industry insiders, the lifting chairs sold by regular manufacturers will issue "inspection reports". The pneumatic rod of the pneumatic lifting chair with a certain risk factor is made of steel and high-purity gas, and the gas is strictly sealed; At the upper end of the pneumatic rod, there is also a verification mark made by the relevant state departments, and the manufacturer, the model and tips of the pneumatic rod are written in English. Generally, there will be an explosion, and the lifting chair uses inferior air poles produced by informal manufacturers.
3. When buying a lifting chair, you can check whether there is a product conformity mark on the chair or on the packing box and the basis for compliance.
Since the general pneumatic lifting chairs have a warranty period, consumers should remember to ask the merchants for invoices when purchasing, so as to avoid insufficient credentials when defending their rights.
You can try to adjust the seat when you buy it to see if it is smooth. It is recommended to buy a lift chair with smooth adjustment.
five
How to use pneumatic lifting chair correctly?
First of all, don't adjust the rotating lifting chair frequently. Many people like to walk back and forth or go up and down repeatedly when sitting in an elevator chair. These sitting postures are very dangerous, and it is easy to cause uneven force on the pneumatic rod. After a long time, the pneumatic rod will wear unevenly, forming an explosion hazard.
Secondly, don't disassemble the lifting chair at will, especially the gas spring part. If maintenance is needed, please call a professional. Some people think it is dangerous to fill the lift chair with gas, so they take it apart and release the gas themselves. Experts remind users that consumers should never deflate according to the online self-disassembling lift chair tutorial to avoid danger. A lot of information on the Internet is not authoritative, and ordinary consumers are prone to accidents in the process of disassembly due to lack of professional knowledge. If there is something wrong with the pneumatic lifting chair, please ask professional maintenance personnel to repair it.
Third, check and maintain the lift chair regularly. If it is found that the adjustment is not smooth or there are other abnormal phenomena, it is recommended to stop using it and find a professional to repair it. Everything has a normal life. Check your chair occasionally. If the lift chair is cracked, loosened and shaken, it should be repaired and replaced in time to avoid tragedy.
Fourth, when using the lifting chair, don't always sit at the front of the chair to avoid the chair being damaged by torsional force.
six
What is a correct and healthy sitting posture?
Very simple, it is "three 90 degrees, 1 center point". While keeping the spine in a natural curve, make the upper body and thigh form an included angle of 90 to 105 degrees, support the whole upper body in the most relaxed way, and reduce the pressure on the lumbar spine; When sitting, the angle between the thigh and the calf with the knee as the connection point should be 90 to 105 degrees, that is, the thigh should be horizontal to the ground and the calf should be vertical to the ground, so that the calf can share the supporting role for the body, thus reducing the supporting load of the hip; When using the keyboard, the upper arm and forearm with the elbow as the connection point should keep an included angle of 90 to 105 degrees, and be properly supported to avoid shoulder discomfort caused by excessive bulging or staying. The user's head should not lean forward or excessively backward, and it is better to stand naturally. His eyes should look straight ahead. His eyes should be in the middle or slightly above the computer screen, and he should not tilt up or down excessively, so as not to bring unnecessary load to the cervical vertebra. There should be an arm's length between the screen and the eyes.
seven
Statistics of injury cases caused by lifting chairs.
Case1:20 April 2007
Location of the accident: Zhoushan City, Zhejiang Province
Victim: Ms. Lou
Results: Perianal soft tissue contusion and laceration, rectal wall contusion
On April 20, 2007, the chair where Ms. Lou was sitting exploded, and a large number of fragments such as hard plastic, sawdust, sponge, cloth and sealing ring collapsed into Ms. Lou's body. After a preliminary examination, the doctor thought that Ms. Lou's injury was very rare. In the perianal area of Ms. Lou, there is a fissure about 2 cm wide and about 10 cm deep at a distance of10 cm from the anal orifice. Due to the serious injury, the doctor immediately operated on Ms. Lou. During the operation, doctors not only took out a lot of hard plastic, sawdust, sponge, cloth and other fragments from the wound, but also took out two other foreign bodies.
Case 2 Time: March 26th, 2008
Location of the accident: Ganzhou City, Jiangxi Province
Victim: Mr. Lin
Results: Back and hands were injured.
At about 1 1 30 pm on March 26th, 2008, a computer chair in a resident's home in Wanjia Xingfu Garden, Jiangbei Avenue, Zhangjia, Ganzhou City suddenly exploded, causing injuries to Mr. Lin's back and hands. The computer chair after the explosion has completely disintegrated; The parts inside the computer chair were also blown up, leaving traces on the ceiling of the bedroom; The board and cotton in the computer chair cushion fell to the ground, but fortunately the injury was not very serious.
Case 3: June 65438+1October 65438+April 2009.
Location of the accident: jiaozhou city.
Victim: Xiaogang, 14-year-old boy.
Results: The rescue failed and he died.
On June 5438+1 October 65438+April afternoon1p.m, 14-year-old boy Xiaogang was surfing the Internet at home. When the rotating lifting chair he was sitting on was adjusting the lifting, the pneumatic ejection device suddenly exploded out of control, and the ejection device with thick fingers was ejected instantly and pushed into Xiao Gang along his hips. Xiao Gang survived because of multiple blood vessel injuries. In this regard, the hospital doctor said that this rotating chair had three accidents in just 1 month.
Case 4 time: 2065438+August 02 1 1.
Location of the accident: Xiamen, Fujian
Victim: Miss Liu
Results: Some fragments may remain in the body and need long-term hospitalization observation.
At 9: 45 p.m. on August 1 1, Miss Liu, who lives in Xiamen, took a shower as usual and sat in the air-pressure lift chair in front of the computer desk to blow her hair. Suddenly there was a loud noise and the chair exploded. Miss Liu immediately fell to the ground and fainted in less than a minute. The doctor said that Miss Liu had a hip injury, a torn rectum and a perforated vagina. Although he is out of danger, he is still weak. And some fragments may remain in the body and need long-term hospitalization observation.
The most important thing to prevent the lift chair from exploding is to be careful when buying it. Buying brands with quality certification and safety certification, the state actually has strict monitoring on these products with potential safety hazards, so you should not be greedy when buying. So how powerful is the explosion of the lift chair?
1. According to the calculation, under normal circumstances, when the air pressure rod under the chair bears the weight of a person, the air in the air pressure rod will be compressed, and then the air pressure inside will reach about 24 atmospheres. Once an explosion occurs, 24 atmospheres times the bottom area of the piston in the outer tubing is the instantaneous explosion power of the pneumatic rod. This force will reach about 70 to 80 kilograms.
2. In the experiment, when the atmosphere is compressed to about 7 atmospheres, the air pressure is released instantly, the ejector pin in the piston is ejected, and a density board is placed not far from the front end of the ejector pin to simulate the surface of the chair. As a result, the density board about three or four millimeters thick is easily broken. In the second group of experiments, they increased the thickness of the density board and placed two density boards. As a result, the two density boards could not resist the impact of seven air pressures. Experiments show that the force generated by 24 air pressures can penetrate at least 6 density plates, which is amazing. It is precisely because of the strong pressure that it has produced such great destructive power.
What should I pay attention to when choosing a safety lift chair?
1. Buy products from regular manufacturers. When consumers buy this kind of pneumatic lifting chair, they must choose a regular product with manufacturer information. Don't covet cheap products, otherwise not only the quality can't be guaranteed, but also there may be no way to defend rights when problems arise. When purchasing, consumers should pay attention to check whether the product has a certificate of conformity, a registered trademark, the name and address of the manufacturer, etc.
2. Carefully choose the chair that is too cheap. According to industry insiders, the lifting chairs sold by regular manufacturers will issue "inspection reports". For the pneumatic lifting chair with a certain risk factor, the pneumatic rod is made of steel and high-purity gas, and the gas is strictly sealed; At the upper end of the pneumatic rod, there is also a verification mark made by the relevant state departments, and the manufacturer, the model and tips of the pneumatic rod are written in English. Generally, there will be an explosion, and the lifting chair uses inferior air poles produced by informal manufacturers.
3. When buying a lifting chair, you can check whether there is a product conformity mark and compliance basis on the chair or the packing box. Since the general pneumatic lifting chairs have a warranty period, consumers should remember to ask the merchants for invoices when purchasing, so as to avoid insufficient credentials when defending their rights.
You can try to adjust the seat when you buy it to see if it is smooth. It is recommended to buy a lift chair with smooth adjustment. To sum up, the information about the explosion of the lift chair is briefly described. I hope it will help you understand the relevant information. Bian Xiao's information is limited for your reference only.