Fire Comments: Unsafe Friction Relief

In recent years, after the government began to list fires in traffic and mine disasters, these fields with the largest number of casualties and injuries were listed as national key targets for prevention and control. High-rise fire escapes have also begun to receive attention and attention from the public. The escape descent device was promoted to urban residents under the promotion of relevant departments and manufacturers of fire protection. However, the problems reflected by the descent during these years had to be contemplating, and the tragedy of the user or the presenter was severed almost every year. Most of the injured can only stay in bed for the rest of their lives, and they are better off than they were. The products that were originally life-saving have become fatal.

People have to ask: These products are not all tested? How many times have accident products been used? Not to mention the requirement of exceeding the minimum standard set by the state 100 times. Why is there a problem?

Because we have problems in our society, when academics and morals are deterred from looking at money, even where medical and educational high-level occupations are contaminated by copper odors, how much can the regulatory authorities do?

How can we use reliable and safe products in numerous descents? This requires some professional knowledge.

Of course, there are also simple ways to judge whether or not to take one of the multiple descents from the descent manufacturer and let the business owner jump off the demonstration from the tenth floor (jump once, then soak the fuselage and jump once more. It is the most effective test. It is estimated that 90% of business owners will choose to escape because of the safety and reliability of many of the products produced by domestic descending manufacturers. They are clearly aware that these products have been fooled on the 3rd and 4th floors. Can (some accidents still happen), to the tenth floor above demonstration, the descent device working time is slightly longer, the temperature rises, the problem arises.

Therefore, a higher floor demonstration is required from the manufacturers. They have no end in mind and can only escape. This was done by a provincial ICBC. They planned to install a number of descents and invited three manufacturers, all of whom were relatively well-known descending descendants. The bank’s office building was only more than 50 meters high and the president was Ask the manufacturer to make a demonstration and then purchase. The bank introduced these factory personnel upstairs and downstairs and watched for more than one hour. The conclusion was that the building was not suitable for installing a descending descent device and it was all running.

When we were engaged in the development of aviation rescue products in the aeronautical scientific research department, our Soviet counterparts had such a requirement that designers and inspection engineers must personally participate in the preliminary testing of new products, and then hand them to pilots to perform tests on rocket vehicles. The test stand is more than 60 meters high. The overload caused by the seat ejection will cause black vision, nausea, and other symptoms to the tester. The loss of rocket seat speed may cause bodily harm to the tester. Therefore, the designer and test engineer The products they developed were never dared to be sloppy. It can be seen from the Soviet air show at the International Airshow that when the planes were out of control twice, the reliability of the escape techniques demonstrated in different flight postures was even more repugnant to Americans. , And come to the door asking for cooperation.

When you are concerned about the descent, you will also consult an expert (now many experts are counterfeit goods, even professional terms do not understand), they may tell you that the C plant products best, the country's first, assuming a day The manufacturer took his product and the leaders of the experts to select the descending device on the 20th floor of a high-rise building. At this time, the building broke fire, and the manufacturers and experts could only use the descending device to escape. We still used the Kramawi fire. With the classic slogan “Give leaders to go first!” that affiliates more than 300 children’s ghosts, you will find that the touted products of the C factory are not dared to be used by the experts’ leaders and the manufacturers themselves are afraid to use them. They may appear. All manufacturers are afraid to escape the ridiculous situation with their own escape descent.

In the view of money to China, the cost of pushing counterfeit and inferior products to the society is very low. Some officials who are not doing so have abandon their principles and have no regulatory role. Many certificates and appraisal reports can be bought with money. Therefore, Some experts have collected the benefits of manufacturers and are not honest when introducing products.

There have been many casualties in the descent in recent years. This is the best explanation. The descending device is not a product like tainted milk powder and shoddy goods. If you eat it wrong, you can correct it. The damage to the body will not be seen for a moment. If the descent device is used wrong, an accident will occur, but the death will be heavy, and if it is disabled, it will be disabled. Only when any production plant and related inspection and supervision personnel should realize that launching unstable, unreliable and descending products to the society is a criminal act that seeks financial harm, people are picking out and producing fires. Escape products will be assured a lot.

When choosing the fire descending device, it is necessary to carefully select and understand the characteristics and principles of the product. Never use your own life to experience such unstable and unreliable products.

The descending device is a personal life-history product, and it must be guided by theoretical knowledge. There is no theory that only strengthening production management can not solve the problem at all. We have dismantled the descending devices produced by the four domestic manufacturers, without measuring and calculating, we can see at a glance. The problems with the products, the production of parts and assembly processes lack theoretical guidance, and are blindly copied products. Entrepreneurs must dare to take the lead to participate in experiments. How can they create products that are not in their own use and can produce stable and reliable products? Pushing unstable products into the community can also prevent legal disputes!

The descent devices produced in China and throughout Asia are basically replicating European early products. Some manufacturers have made some improvements. The principle of the friction-type descent device is like this, and all are based on the principle of centrifugal friction damping. The rate of human body's descent, due to non-metallic material friction plate affected by the external temperature, humidity, chemical gases, dust, the friction coefficient is not stable, resulting in unstable friction, a lot of accidents, so the technology slow down The device is prohibited in some states of the United States.

Centrifugal friction type descending gear structure is relatively simple (understand to see), fixed body rope tightly around the winding wheel drive speed increasing wheel train, so that the centrifugal block guide bracket high-speed rotation, driving the centrifugal block centrifugal force, fastening The non-metallic friction plates on the friction friction with the circular shell or a fixed ring, the friction force generated by the damping of the winding wheel speed, to achieve the purpose of human body to slow down, this product has two key The technical indicators, centrifugal force and friction coefficient of non-metallic materials, in use, these two data are not stable, can not control the theory, leading to instability in the work of such products prone to out of control accidents. From the direction of the improvement of such products in Europe and the United States, it can be seen that the early products in Europe and the United States basically use planetary gear trains. The centrifugal block of the fixed friction plate is active and has multiple degrees of freedom. In use, the contact surface between the friction plate and the housing is fluctuating. Is not an ideal state, and the centrifugal force generated by each centrifugal block is not the same, it will produce parts vibration, friction and damping will continue to change; In addition, the shell is polished, the temperature is high, the friction damping also changes, will bring a The series of problems, the current domestic production of the descent device is the structure of this structure, the only advantage of this structure is the low production costs, three planetary gear meshing at the same time (some domestic manufacturers only use one or two planetary wheels, obviously the enterprise There is a lack of mechanical transmission knowledge, and it is not easy to have broken teeth under the action of impact force. The disadvantage is that the planetary gear train has a small transmission ratio, which is not more than 5.2 . The centrifugal force produced is small and unstable, and the quality of the centrifugal block is increased to bring about new ones. The problem is that the body of the escape is descending more slowly. In order to increase the speed and stabilize the friction, the diameter of the rope on the tethered wheel has to be reduced. The result is that The damage to the rope is greater. The free movement of the mass of the centrifugal block and the roughness, clearance, guide distance, etc. of the guide component will affect the mechanical efficiency of the centrifugal block when moving, and people of different weights will have different vibration frequencies and unsafe work will occur. Frequently, some people use multiple times without incidents, and individuals will have a problem.

Friction-type descending device is required to be erected vertically in use, and maintain a certain distance from the wall surface to prevent the descending device from oscillating and colliding with the wall during use, to generate axial momentum and affect the movement of the centrifugal block. These are as far as possible. Its working state is idealized to avoid the risk of loss of control due to centrifugal force fluctuations. This type of product has a round appearance. When it is shaken, it can hear the sound of a moving centrifugal block colliding with the housing.

In recent years, Europe has introduced a second-generation descending descent device. In order to increase the gear ratio of the train and reduce the impact resistance, ordinary wheel train transmissions are used, and centrifugal friction weights are connected by rotating shafts to limit the degree of freedom. New friction materials are used, the friction coefficient changes with the force, and it is affected by the temperature and humidity, and does not absorb water. In order to ensure safety, some manufacturers in Europe and America use double friction mechanisms to improve the stability of the product. At the same time, the new descending standards in Europe and the United States require that the descending device be soaked in water for one hour, and that after removing 15 minutes from the water , it can be used normally. At present, there is no domestic research on the friction plate of the descent device. The descent device manufacturer can only use the non-metal materials of other industries to replace the friction plate, which also causes the product's inherent deficiencies.

Regardless of how the centrifugal friction type descending device is improved, it is still afraid of flooding and oiling, and its frictional balance and damping all fluctuate. The frictional balance force is affected by the rotation speed, the mass of the centrifugal block, the friction coefficient of non-metal materials, and the mechanical efficiency of mechanical transmission components. The influence of factors such as vibration frequency, external humidity, temperature, dust, and different body weights will make the descent device's stability at work challenging. The reliability technical indicators of the product cannot be passed theoretically, and its safety is inherently problematic. Similarly, users of this type of product will inevitably have their hands and feet raised against wall bulges or window ledges during descent, all of which will cause dangerous changes to the desired working conditions of the descent. Therefore, the poor quality descent device loses control only when it is performed on the 3-4th floor. Obviously, there is a problem with the movement of the centrifugal block and the centrifugal block, or the effect of dust, and the centrifugal force cannot be stabilized; a good descent device is in use. Some time ago, it was working normally and suddenly it was out of control. Obviously it was related to temperature, frequency, unstable friction materials and dust. The impact of working vibration frequency on the descent device was estimated that 99% of domestic production plants neither knew nor had the ability to study this technology. problem.

Our country is extremely weak in the scientific research field of high-rise fire escape products, mainly due to lack of theoretical basis. Before the reform, China's outstanding talents and scientific research costs were first used in the military industry. At that time, senior engineers, experts, etc. were very few. They learned a lot of scientific research achievements in the next-to-first-line practice. Now, a large number of doctors and experts have emerged, and there are still few technical personnel who can solve practical problems and can innovate and develop practical applications. The number of product researchers is very small. Although there are also many companies, factories, and research departments in the field of fire protection in the country, it is difficult to make achievements in the field of fire escape. For example , after the fire in Shanghai 11.15 , the fire rescue cabin urgently needed by the national high-rise buildings is so low in difficulty. Scientific research products have not seen professional-level design solutions for many years.

If you are still confused, it is recommended that when using a descent device, such as the model number TH-35/100-15, the last one is a descent device with a number of 15 , this type of product is basically a product that can barely pass, and its price is a few. Hundred RMB, the rope used in this type of descending device is a rope-clamped wire rope structure (the wire rope is rusted, the appearance is not visible, the steel wire is broken, the rope is broken), and the domestic production of such ropes is of poor quality. We tested a few products, the rope breaking force is only within 630 kilograms , after the end of the rope, the pull will drop 15% -30% . Because there have been many accidents due to insufficient rope strength, Jilin Province has not allowed the use of such descending devices in fire protection. Europe and the United States are also eliminating such slow descending products. It's best not to buy a product that you want to protect your life. Choose the last one that is a 25 or 30 descent device to purchase. At least the descent device at the last 15 is a little safer, but don't forget that this kind of descent device Insecurity has always existed, especially after two years of storage. Do not try this product casually! After the descending device was controlled and sold in China, people did not save one, but it caused casualties to presenters and users, reaching dozens of people!

If any of the above is incorrect, please correct me.

The information in this article comes from the Internet and was reorganized and edited by China Rescue Equipment Network.