On the problems existing in the automatic control

2022-08-13
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On the problems existing in the automatic control of fire doors

0. Introduction

Article 5.4.2 of the code for fire protection design of high rise civil buildings GB stipulates that fire doors used for evacuation walkways, staircases and antechambers should have the function of self closing. Normally open fire doors shall have the function of self closing and signal feedback in case of fire. This provision was included in the mandatory code for engineering construction in 2000 (not included in the 2002 Edition); Article 6.3.7 of code for design of automatic fire alarm system GB: the control of normally open fire doors by fire control equipment shall meet the following requirements: 6.3.7.1 after the fire detector on either side of the door gives an alarm, the fire door shall be closed automatically; 6.3.7.2 the fire door closing signal shall be sent to the fire control room

surprisingly, the author has participated in engineering review for many years and found that most high-rise civil building projects have normally open fire doors, but few design drawings implement the above specifications. The construction units involved in the fire alarm system project designed by the author said that they had never installed a fire door control system before, and had never heard of a fire door release switch; The salesperson of the alarm equipment factory reported that the design drawings rarely designed the automatic control of fire doors; The fire door release switch is rarely set in the normally open fire doors of built projects and even high-end hotels; According to the fire door release switch manufacturer, few people purchase fire door release switches in many cities. Therefore, the author feels that in small and medium-sized cities, the above normative provisions are almost in vain

is the specification not strict enough? Obviously not, just look at the standard words. Are often open fire doors rare in high-rise buildings? It can be concluded from the author's following that it is actually very common. Is the cost too high? No, the ex factory price of the fire door release switch is 350 yuan/set (the price of imported products is thousands), which is a little more expensive than a probe! Compared with the electric fire shutter, it is almost a fraction. What's the problem? What will we do

1. Analysis of the reasons for not implementing the specifications

first of all, the design drawings of the construction profession usually do not indicate which fire door is normally open and which is normally closed. The electrical designers have not analyzed the building function in detail, thus ignoring the normally open fire door, which is the main reason

secondly, a few electrical designers are not familiar with the specifications

thirdly, the research and development of automatic fire alarm wear-resistant wiping experimental machine has been for many years. Equipment manufacturers generally do not produce fire door release switches. The system examples in their product samples rarely list the automatic closing of normally open fire doors, and there is no detailed automatic control practice of fire doors, which makes designers unfamiliar with the design method

in addition, the domestic fire door release switch manufacturers do not have enough publicity. They often focus on promoting fire doors, door closers, etc., which makes electrical designers do not understand the product, which is also an important reason

finally, some designers may have misunderstandings, thinking that normally open fire doors need the same complex control as fire shutter, that electric fire doors need motors to control, that the system is as sophisticated and expensive as automatic doors, and that it needs to provide strong current dual power supply, etc., so they are afraid of difficulties and deliberately avoid

2. Place of use and purpose analysis of fire doors as long as the extension meter is installed

fire doors are divided into normally closed fire doors and normally open fire doors according to the open state

normally closed fire doors usually do not need the electrical discipline to provide automatic control design, but some cases, such as: normally closed fire doors on evacuation routes, When the construction party has anti-theft and other management requirements (it is often reported that a unit has closed the fire door on the evacuation exit and been punished for rectification, or that people have died in a fire, because the owner has locked the fire door on the evacuation exit and the personnel cannot escape, resulting in a tragedy. It can be seen that the conflict between fire protection and security is very common), it should be designed with the cooperation of the electrical profession, although there is no requirement in the current fire code, However, designers can help the owner solve the contradiction between fire protection and security

for normally open fire doors, automatic control design must be carried out by the electrical discipline

how to judge whether the fire door is normally open? The fire door on the evacuation passage with more people and logistics is usually a normally open fire door. For example, class II high-rise buildings and class I high-rise buildings with a height of more than 32 meters must be equipped with fire elevators. Building professionals often use passenger elevators as fire elevators, and the elevator lobby and closed staircases (or smoke-proof staircases) often share the lobby. This situation is very common, and it exists in a large number of high-rise buildings with small volume. The fire door connecting the shared front room and the evacuation passage is a standard normally open fire door, because the main flow of people and logistics must enter the shared front room through the fire door to take the elevator. There are also: for high-rise buildings with large volume, the fire doors that play the role of fire compartment on the evacuation passage are often open fire doors with a lot of people and logistics at ordinary times

it can be seen from the above two cases that normally open fire doors generally exist in high-rise buildings

don't control yourself if you make the normally open fire door normally closed? The author believes that it is absolutely not possible, because the opening and closing of the fire door takes a little effort, and it is extremely inconvenient to get in and out of the fire door (and the service life of the fire door and accessories will be greatly reduced due to frequent opening and closing collisions). It is often that the pull rod of the door closer is removed from work, or the fire door is fixed on the wall. When the fire came, everyone rushed for their lives. Who remembered to close the fire door in the panic? Even if someone calmly closes the door, the fire door at this time may be fixed and difficult to close quickly, while the fire door with the door closer damaged will lose the closing elasticity, and the free door will be useless even if it is closed. It can't withstand the impact of the expansion of the fire hot air, so the shared front room will be swallowed by fireworks, and the enclosed staircase (or smoke proof staircase) for escape will no longer be safe, Firefighters can't enter the front room from the fire elevator to save people and put out the fire, and the consequence is that the displacement accuracy is quite serious

therefore, the normally open fire door must not be normally closed

normally closed fire doors are generally composed of fire door leaves, door frames, door closers, seals for products and equipment that are more suitable for users. Double or multiple normally closed fire doors are also equipped with sequencers

in addition to all accessories of normally closed fire doors, fire door release switches must be added for normally open fire doors

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