Keywords: fire alarm, engineering estimation, detector, alarm system, fire protection code
According to the Code for Design of Automatic Fire Alarm System in China (GB50116-98+06-98), the relationship between building area and automatic fire alarm system is analyzed in combination with the conventional design characteristics of automatic fire alarm system in domestic civil buildings and a large number of engineering budget and final accounts. Finally, a set of investment estimation method of automatic fire alarm system is proposed.
abstract
The estimate mentioned in this paper is completely different from the budget. Before the design drawings are finalized or not drawn at all, some investors often ask suppliers or designers to estimate the approximate amount of a fire fighting project. This paper only discusses the investment estimation method of fire alarm engineering, hoping to help investors, planners or designers.
According to the Code for Design of Automatic Fire Alarm System (GB50116-98+06-98), the automatic fire alarm system (hereinafter referred to as alarm system) has at least two trigger devices, namely, fire detector (hereinafter referred to as detector), smoke detector (hereinafter referred to as smoke detector) and temperature detector (hereinafter referred to as temperature detector). Manual trigger device, as the name implies, is the manual fire alarm button (hereinafter referred to as manual report); The alarm system has at least one fire alarm controller (hereinafter referred to as the controller), including the fire power supply unit: there are alarm devices, and the most commonly used is the fire alarm bell: most alarm systems have system wiring.
What non-professionals need to pay attention to is that the choice of alarm system must be based on a brand, that is, a manufacturer. You can't choose this manufacturer because of cigarettes, but because of the temperature, the controller will find another one. Users can ignore whether these controllers, temperature sensors, smoke sensors or handwritten newspapers come from a company. In short, only one company has been identified.
1. Alarm detection section
In most civil construction sites, the most commonly used part of alarm system is smoke sense, followed by hand report and temperature sense. The alarm detection part may have signal modules, i.e. the action signal of fire hydrant button, the action signal of fire damper in air conditioning system and the action signal of water flow indicator in water spraying system. And converted into a detection signal recognized by the alarm system. There are also infrared beam detectors, ultraviolet flame detectors, combustible gas detectors, explosion-proof detectors and so on. Some manufacturers of alarm system products do not necessarily produce ultraviolet flame detectors, explosion-proof detectors and other detectors. Through the signal module, the matching use of alarm products from different manufacturers can be realized. When estimating, a detection unit is called an alarm point, and the number of alarm points is called alarm points.
1. 1 smoke sense
In order to facilitate the analysis, the following discussion begins with the simulation of building a hotel. In hotels, office buildings and other buildings, the most commonly used detector is smoke detector. The smoke detector of the alarm system is most suitable for places where there is smoldering stage in the early stage of fire, which produces a lot of smoke and a little heat and little or no flame radiation. Now suppose: an investor wants to build a hotel. Most rooms have an average of 28m2, with a total construction area of 30,000 m2. The design work has not yet started.
According to the specification, the protection area of a smoke sensation is between 60 ~1.20m2.. Because the ceiling height of most rooms in the hotel is less than 6m, and most of the roofs are flat-topped (all the roofs mentioned in this paper are flat-topped), the maximum protection area of a smoke sensation can only be 60m2. According to the specification, each room in the detection area of the alarm system should be equipped with at least one detector, and two rooms in the suite cannot share one detector. At least one smoke detector is set on the ceiling of the inner walkway with the width less than 3m at15 m. The width of the inner walkway in the hotel is generally about 2 m (the inner walkway with the width greater than 3 m is treated as a room), and the average protection area of the smoke detector used on the inner walkway is less than 30m2, which is also taken as 28m2 in this paper. In the office buildings of hotels or similar hotels, there are large rooms, such as dance halls, gyms, equipment floors and other places, and the protection area of a smoke sense can theoretically reach 60㎡. In fact, limited by various conditions, the protection area of a smoke sense can be almost 60 ㎡. Especially in the case that the ceiling is not decorated on the roof, the protection area of smoke is far less than 60 ㎡ due to the influence of beams. In many places, such as small offices, service rooms, floor distribution rooms, floor air-conditioning rooms, karaoke hall tuning rooms, etc., the design area is less than 30 ㎡, and only one room can be equipped with smoke detectors. Weighing the average utilization rate of smoke, according to the statistics of budget and final accounts of 100 alarm system project, the average protection area of a smoke is about 37 ㎡. According to the statistics of budget and final accounts of 30 hotels, guest houses, hospitals and office buildings, the average protection area of a smoke sensation is about 26 ㎡. Here, based on the above, the average room area of most rooms is 28 square meters, and the average D6 protection area is 28 square meters.
1.2 manual report
According to the specification, the alarm system must be equipped with a manual alarm, and each fire zone must be equipped with at least one manual alarm. The distance from any position in a fire zone to the nearest handwritten newspaper is not more than 30 m. Handwritten newspapers should be set at the entrances and exits of public places. Usually, handwritten newspapers are set up in the corridors, elevator halls, safe passage entrances and exits, and hotel halls of hotels. Because the use and partition of each floor of each building are different, and the design of evacuation passages is also different, it is difficult to find a layout law of handwritten newspapers.
Let's draw two pictures and give two simple columns.
Figure 1 shows that there are two leaflets in a 56 m corridor, with walls and windows on one side and rooms on the other. There are no detectors in corridors and stairwells, but 1 1 smoke detectors are installed in rooms and elevators, and the dosage ratio of manual report to smoke detectors is 1: 6.
Figure 2 shows that there are two handwritten newspapers in the 56 m corridor, rooms on both sides of the corridor, four smoke detectors in the corridor, and 30 smoke detectors in 25 rooms and elevators. The consumption ratio of handwritten newspaper to smoke detector is 1: 15.
The handwritten report can neither be shared by area nor enjoy the protected area of the detector. After years of practice and statistics, if a proportional value is quoted in the engineering estimation of alarm system, there will be as many manual reports as detectors. According to the statistics of alarm system engineering budget 100, the consumption ratio of manual reporting and smoke detection is about 1: 8.5. According to the statistics of budget and final accounts of 30 hotels, hotels and commercial office buildings, the consumption ratio of smoke sensation by manual reporting is about 1: 12.7.
Here, the dose ratio of handwritten newspaper to smoke sensation is 1: 10.
When doing statistics, there are construction drawings or as-built drawings, and there are clear signal modules to quantify. Investors here only know that the total area of the building to be built is 30,000 ㎡, and nothing else has been decided. Therefore, it is necessary to appropriately reduce the proportion of manual tobacco reporting. It is also possible to appropriately reduce the protection area evaluated by the detector from the beginning.
1.3 temperature sensing
According to the specification, in the kitchen, garage or underground garage of the hotel, where there is steam or humidity, the detector chooses to use a temperature sensor. According to experience, the ceiling height of small rooms in hotels and restaurants is less than 2.5m, and the phenomenon of hot pot often occurs, so it is best to use the sense of temperature. The use of this warm feeling is very common, not limited to hotels. According to the specification, the protection area of a temperature sensor is between 20 and 40㎡, but a room with a temperature sensor protection area of 40 ㎡ must have a sloping roof greater than 30. This phenomenon is not common. A large number of statistics have proved that the average protection area of a temperature sense, like a smoke sense, will not reach the upper limit allowed by the code, and the average protection area of a temperature sense is smaller than that of a smoke sense. In the estimation, the calculation of temperature sensitive dose and protection area can be treated as smoke sensitive. Because the total cost of setting a temperature sensor is lower than that of setting a smoke sensor. There are two and a half reasons for this. First, the fixed labor costs set by the local installation labor management departments are lower than the smoke. Secondly, the wiring cost allocated to a temperature sensor is low, partly because the price of temperature sensors in many manufacturers is lower than that of smoke sensors. When the sum of temperature sensing areas accounts for more than 15% of the total building area, the temperature sensing amount can be calculated separately. According to the statistics of budget and final accounts of 20 garage alarm systems, the average protection area of a temperature sensor is about 15m2. When the number of building temperature sensors accounts for half of the system, temperature sensors can be used as the dominant factor to estimate, and the ratio of manual report to detector can be reduced. For example, the ratio of manual report to detector in the garage may be 1: 20. For another example, restaurants with more private rooms in RTV and KTV should have a sense of temperature because of the serious smoking phenomenon in private rooms, and the room separation is relatively small, with more detectors, but the amount of manual reporting will not be much. On the premise of the same area, the investment in building an alarm system in an indoor garage is higher than that in an indoor bicycle garage, because the bicycle garage can prevent smoking.
1.4 Other detectors
In hotels or office buildings with catering services, several combustible gas detectors (gas detectors) should be considered. In some cases, infrared beam detectors must be used, and so on. Gas detectors are generally installed in gas meter rooms, kitchens or gas pipeline wells, and most of them are arranged within 30 ㎡ in actual use. In this way, in the engineering estimation of the alarm system, the combustible gas detector is regarded as smoke-sensitive and allocated according to the unit area. The biggest error of this estimation method is the price of the detector, and the investment in labor and wiring is similar. At present, the price ratio between gas detector and smoke detector is about 4: 1 to 6: 1 if the smoke detector is calculated by 300 yuan (including a signal conversion interface device has been considered here). After years of practical experience and statistics, in hotels, office buildings with catering services, administrative complex buildings and other civil buildings, gas detection accounts for a small proportion of the total investment in a building alarm system. When the number of gas detectors, beam detectors and explosion-proof detectors accounts for more than 2% of the number of smoke detectors, the alarm equipment fee of such detectors can be regarded as smoke detectors after adding the coefficient according to the above information.
As for other signal modules and interface modules that should be regarded as detectors in the detection part of the alarm system, they have been included as smoke sensors, manual alarms and temperature sensors according to the allocated area. Therefore, the evaluation area of smoke sensation should be appropriately small, or the ratio of hand report to detector should be appropriately small. In fact, the estimation of the above detectors should be said to be the alarm point of the alarm system. When estimating, it is determined that the temperature sensor depends on the smoke sensor, and the ratio of manual report to smoke sensor is 1: 10. The alarm point of this hypothetical building is:
(30000m2 ÷ 28m2/point) × (1+10) ≈1072+108 =/kloc-0.
When estimating, it is known that there is a ***6 100 ㎡ second-floor underground garage in the 30000m2, and the alarm point of the building is:
(23,900m2 ÷ 28m2/point) ×( 1+10)+(6100 ÷15m2/point) × (/kloc-0)
When estimating the equipment cost of an alarm point, we can't say what is the lowest price of smoke sensor or temperature sensor, because as mentioned above, an alarm point may be smoke sensor, temperature sensor, manual report, signal module and so on. As an alarm point, this paper provides a more economical estimated price: an alarm point 300 yuan. This means that if you invest in 300 yuan, you can definitely buy some common alarm devices, such as smoke, temperature, manual alarm, signal module and so on, which meet the fire protection requirements.
If investors have higher requirements for fire-fighting equipment, an alarm point can be increased by one grade every 50 yuan, such as 350 yuan, 400 yuan and 900 yuan. When investors make preliminary estimates, if the equipment price of an alarm point is calculated according to 900 yuan, then the main equipment of the alarm system can choose the most advanced fire alarm series products imported from all over the world.
An alarm point, in addition to the alarm equipment costs, there are equipment installation costs. As the cost of installation and construction, all provinces, cities and regions in China are not uniform. Even within a province, there are differences between cities and regions. But unlike the main equipment, 300 yuan to 900 yuan can be chosen by investors at will, and it should be calculated according to the local installation labor quota. Strangely, Shanghai is recognized as one of the cities with higher average wages in China, but the labor quota for installing alarm system equipment in Shanghai is not the highest in China. But no matter which area, as the calculation of the labor cost of the alarm system, the selection of the main equipment of the system has little to do with the labor cost. An alarm point can be economical or luxurious, and the installation cost remains unchanged. Based on Shanghai's "93-quota, Class III installation project" standard, combined with some local data and the author's many years of experience in implementing fire fighting projects in various places, smoke detection is the main detection equipment of the system, and the number is balanced at a medium level.
The equipment installation fee for an alarm point is 200 yuan/Taiwan (availability coefficient of municipal government or equivalent provincial capital city 1. 1).
In order to set the alarm point, there must be corresponding building installation materials such as wires, conduits and junction boxes and building installation labor costs. With the reform and opening up, the differences between regions are getting smaller and smaller. Its quantification, this paper makes the following analysis.
According to the specification, the maximum protection radius for smoke and temperature is 9.9m and 6.3m respectively. Due to the limitation of space, this article will not introduce the circumstances under which the specification allows the protection area of detectors to use its upper limit. In fact, the engineers of the design institute should consider leaving design margin when designing to avoid the problem of detecting dead corners, so it is impossible to get the upper limit. However, considering that the wiring direction of the conduit in the building is not necessarily a straight line, and considering the lead part of the system, the maximum protection radius of the conduit shared by each alarm point is 9.9m (it may be 10m). According to the specification, DG series conduit and RVS series double-color twisted pair are best used for alarm system wiring. As a two-bus detection loop, it is enough to use DGl5 as the specification of conduit, but considering that the system is small but the construction cost is not small, the conduit larger than DG20 will be used when the system is large but the construction cost is not large. When estimating, the specifications of the conduit are unified as DG20. According to the Specification, the conductor specification of bus circuit is insulated conductor, with a voltage resistance of 500V,1.0m2, which is enough to meet the requirements. However, according to the introduction of the design institute, the mechanical tensile strength of wires in wiring construction is generally1.5m2 RVS double-color twisted pair. In this way, for each alarm point, the shared electric conduit DG20 is 10m, the shared electric wire RVSl.5 double-color twisted pair is 1.3 times that of the electric conduit, at least one junction box is shared, and the shared junction box is 1/20 (if there is less than one, it is counted as one), and so on.
After calculation, the total cost of materials and labor (wiring) for installing and constructing an alarm point is about 220 yuan.
The equipment fee for an alarm point is 300 yuan, the alarm equipment installation fee is 200 yuan, and the wiring fee is 220 yuan, totaling 720 yuan.
The investment for setting alarm points is estimated to be 720 yuan/Taiwan.
The alarm system is mainly based on temperature sensing, the temperature sensing is measured by 270 yuan/set, and the electric conduit is measured by 7m/ set. The estimated price of an alarm point is set as 600 yuan/set.
2. Alarm alarm part
According to the specification, each fire zone is equipped with at least one fire alarm device. Because this function is the same as manual reporting, engineers usually set the number of fire alarm devices to be the same as manual reporting. The most common phenomenon of the alarm system that has been put into use now is that there is a leaflet about 1.4m above the corridor wall, and there will be a fire alarm bell (or audible and visual alarm) about 0.7m above the leaflet (under the ceiling). For buildings with high fire protection requirements, there are not only fire alarm bells, but also fire horns. Because the fire broadcast system is allowed to cooperate with the building background sound system at ordinary times, it meets the requirements as long as the background sound system can forcibly enter the fire in an emergency. For this reason, when buildings have high requirements for background sound, such as star-rated hotels, the requirements for their sound reinforcement equipment and speakers are quite high, and the price gap is also very large, which cannot be used as this part of the budget for fire protection system engineering. In general broadcasting system, for example, the speaker used is 3w power, the market price is around 70 ~ 99 yuan, and the fire-fighting broadcasting sound reinforcement equipment used is below 300w power, and the total market price is less than 9000 yuan. Such a fire broadcast system can be estimated as a whole with the alarm system and included in the fire investment budget. Generally, the fire alarm bell is a round red bell with a working voltage of 24V and a diameter of 150mm, and the market price is about 1 10 ~ 190 yuan. Audible and visual alarm generally uses electric bell, which works at 24V and has a rectangular shape. It can not only flash red light, but also sing. The market price of a bell is about 2 10 ~ 290 yuan. In contrast, the speaker seems to be cheaper than the fire alarm bell, but it is not, because the radio has amplification equipment. No matter whether fire alarm bells, audible and visual alarm or fire speakers are installed, no matter the size of the alarm system, they are collectively called alarm device units when estimating, and the number is the same as that of manual reports, but the wiring is different from that of manual reports. The wiring of the manual telegraph is regarded as a detector, and the specification of the wire conduit configured for the manual telegraph is related to the system size, while the specification of the wire conduit configured for the alarm device is not related to the system size. The maximum distance between the manual telegraph and the manual telegraph is 30m, but the wiring is 10m/ m.. The distance between the alarm device and the alarm device is calculated as 30m, and the wire tube instrument 15m and the wire tube specification DG 15 are shared on one alarm device. No matter the size of the alarm system, there are always only two wires used in the alarm device. The RV2× 1.5 double-stranded wire is 1.2 times the length of the conduit, and there is at least one junction box.
The unit alarm equipment fee for an alarm device is estimated at 160 yuan.
In order to set the wiring fee for an alarm device, the estimated price is 290 yuan.
Subtotal, alarm device, estimated price of 450 yuan/set.
When the system has both fire alarm and fire broadcast, the number is doubled.
3. Alarm control part