Design and calculation of spray in mechanical garage- Liu Ke

           Design and calculation of spray in mechanical garage-Liu Ke
1. Regulations: “Code for Fire Protection Design of Garages, Garages and Parking Lots” GB50067-2014 Article 7.2.6: 7.2.6 Automatic sprinkler systems installed in garages and garages shall be designed in addition to In addition to the current national standard “Specifications for Design of Automatic Sprinkler Systems” GB 50084, the sprinkler arrangement should also meet the following requirements: 1 It should be set above or above the parking space of the garage. For mechanical garages, it should still be Arrange the parking car boards in layers, and heat collection boards should be set above the sprinklers; 2 Nozzles should be set above the driveways and ramps of the split-level and inclined floor garages. The design of the sprinkler system has been specified in the current national standard “Specifications for the design of sprinkler systems” GB 50084. When designing sprinkler systems for garages and garages, the sprinkler strength and effect The area, the working pressure of the sprinkler, the maximum protection area, the maximum horizontal distance, etc. and the water consumption of the automatic sprinkler shall be implemented in accordance with the relevant provisions of the “Code for Design of Automatic sprinkler systems” GB 50084.
In addition, according to the characteristics of the garage, this article sets out some special requirements for the nozzle arrangement. The parking position of most garages is fixed. It is found in the survey that the sprinklers installed in most garages are arranged in accordance with general practices and according to the area and the distance between the sprinklers. The lower part is directly protected, the car fires, the sprinkler head is not protected, and the fire extinguishing effect is poor. Therefore, this article stipulates that the sprinkler head should be arranged on the parking space.
The parking position of a mechanical garage is both fixed and moved up, down, left, right, front, and back, and the floor height is relatively high. Therefore, this article specifies the layout requirements of both a lower nozzle and a side nozzle. It is necessary to ensure the effective fire extinguishing of the automatic sprinkler system of the mechanical garage.
Split-level, inclined-floor garages are difficult to separate from the fire zone, and it is difficult to separate the parking area from the driveway. Some appropriate adjustments have been made in the fire zone, but in order to ensure the safety of these garages and prevent fire Spreading and expansion, adding sprinklers above the lanes and ramps is a very necessary remedial measure.
2. Atlas requirements: 05SS904 “Analysis and diagrams of common problems in the design of civil construction engineering”-water supply and drainage engineering 5-24 Missing nozzles on the parking tray on the bottom of the mechanical three-dimensional parking garage See the above picture.
3. “Self-spraying Design Manual” P171: 4.12.2 The three-dimensional garage is equivalent to a high-bay warehouse. The design of the automatic sprinkler system should consider the number of sprinkler movements in the frame of each floor in addition to the sprinklers in the ceiling area. According to the old spray gauge 5.0.7, the number of built-in sprinklers in high shelves should be calculated based on the movement of 4 sprinklers, but NFPA13 stipulates that the sprinklers in multi-layer shelves can calculate the water consumption of sprinklers in the shelves according to 14 sprinklers. Considering the three-dimensional garage It is recommended that the number of nozzles built into the frame should be calculated according to 4 ~ 8 nozzles when there are two layers of three-dimensional garages; when it is more than three layers, the number of nozzles built into the frame should be calculated according to 8 ~ 14 nozzles. The three-dimensional garage is still considered according to the second level of danger. The water output of each sprinkler of the built-in sprinkler on the shelf should be 115L / min, and the quick reflection sprinkler should be adopted. The water consumption of the self-spraying system of the three-dimensional garage is the water consumption of the self-spraying system on the ceiling plus the water consumption of the sprinkler built into the frame. The high-level foam fire extinguishing system should be used in the three-dimensional garages with more than three floors. The three-dimensional garage should adopt a foam-automatic water spray combined system, and the water spray intensity at this time is not less than 6L / min.m2.
4. “National Civil Construction Engineering Design Technical Measures 2009 Edition”: P241 Article 8: The automatic sprinkler system for indoor mechanical garages has a shelf-built sprinkler warehouse design calculation method to determine the design flow. 4.1 When there is only one layer of built-in sprinklers in the frame, the number of built-in sprinklers in the frame may be eight; 4.2 When there are two or more built-in nozzles, the number of built-in sprinklers in the frame may be 14; Article 14: The design parameters of the ceiling of the mechanical multi-layered three-dimensional garage are determined according to the medium danger level II. For the number of nozzle openings of other layers, please refer to Section 7.2.13, Section 7 and Table 7.2.13-11.
7.2.13 Paragraph 7: When the maximum clearance height or maximum storage height of the shelf storage warehouse exceeds the regulations (see the attached table), a row of sprinklers should be set at a height of 4 meters from the ground. When the sprinkler flow system K = 80 The working pressure should not be less than 0.20MPa; when the nozzle flow system K = 115, the working pressure should not be less than 0.10MPa; the nozzle distance should not be greater than 3 meters, and it should not be less than 2 meters. The number of open sprinklers in the shelf is as follows:

7.2.13-11 indicates that the built-in sprinkler of the three-dimensional garage frame refers to the residential self-spraying system, and a fast response sprinkler shall be used. Nozzle arrangement of the eighth mechanical stereo garage: a. There should be two sprinklers above each vehicle. b. Upright or pendant nozzles should be adopted, and side wall nozzles can also be used according to the mechanical operation mode; c. The nozzle arrangement should meet the requirements of moderate danger Class II. Design the warehouse with built-in nozzles on the shelf, the nozzles under the roof and the nozzles in the shelf. The sprinkler shall calculate the flow separately and determine the design flow of the system according to the sum of its design flow.
5. Spray calculation: In recent years, the design flow required for mechanical three-dimensional garages varies greatly. According to the recommendations of the plan review company and the habits of different regions, the design flow of over spray is 30L / S; 45L / S; 50L / S; 60L / S and other parameters. As there is no normative reference, various flow values ​​have emerged in the project. a. Those who take 30L / S think that according to the self-spraying manual, the flow of additional nozzles is not counted, or the deduction in the frame is considered.
The coverage area of ​​the spray head, the overall active area remains unchanged, still taking 30L / S. This obviously contradicts Article 4 “Technical Measures” mentioned earlier and is not desirable.
b. If K = 80 sprinkler is used, according to the requirements of “Technical Measures”, the system design flow shall be the design water consumption of the ceiling automatic sprinkler system plus the water consumption of the built-in sprinkler in the frame. The standard flow rate of the sprinkler shall be 1.33L / S. The first-layer frame takes 8 nozzles, Q = 30 + 1.33×8 = 40.6, and takes Q = 45L / S; the second-layer frame takes 14 nozzles, Q = 30 + 1.33×14 = 48.6, and takes Q = 50L / S.
c. If K = 115 sprinkler is used, according to the “Technical Measures”, the system design flow rate shall be the design water consumption of the ceiling automatic sprinkler system plus the water consumption of the built-in sprinkler in the frame. The standard flow rate of the sprinkler shall be 1.92L / S. The first-layer frame takes 8 nozzles, Q = 30 + 1.92×8 = 45.4, and Q = 50L / S; the second-layer frame takes 14 nozzles, Q = 30 + 1.92×14 = 56.9, and Q = 60L / S.
d. According to the “Self-Spraying Manual”, if K = 80 sprinklers are used, the system design flow rate shall be the design water consumption of the ceiling automatic sprinkler system plus the water consumption of the built-in sprinkler in the frame. The standard flow rate of the sprinkler shall be 1.33L / S. The first layer of the frame takes 4 nozzles of the lower limit of the nozzle, Q = 30 + 1.33×4 = 35.3, take Q = 40L / S; the second layer of the frame takes 8 nozzles of the lower limit of the nozzle, Q = 30 + 1.33×8 = 40.6, take Q = 45L / S.
e. Similarly, according to the “Self-Spraying Manual”, if K = 115 sprinkler is used, according to the “Manual”, the system design flow rate should be the water consumption of the ceiling automatic sprinkler system design plus the water consumption of the built-in sprinkler in the frame. The sprinkler standard The flow rate is 1.92L / S. The first layer of the frame takes 4 nozzles of the lower limit of the nozzle, Q = 30 + 1.92×4 = 37.7, take Q = 40L / S; the second layer of the frame takes 8 nozzles of the lower limit of the nozzle, Q = 30 + 1.92×8 = 45.4, take Q = 50L / S.
6. Relevant viewpoints: At present, the most common practice is: when using a sprinkler system, take Q = 45 ~ 50L / S for the first frame, Q = 60L / S for the second frame, and Q = 30L / S; Q = 30L / S is always taken when using the foam-automatic water spray combined system. There is a view that the number of sprinkler heads controlled by an alarm valve group according to “Spray Regulations” 6.2.3 should meet the following requirements: 1 wet systems and pre-acting systems should not exceed 800; dry systems should not exceed 500; 2 when the water distribution branch pipe When setting sprinklers that protect the space below and above the ceiling at the same time, only the sprinklers on the larger side should be included in the total number of sprinklers controlled by the alarm valve group. 7.1.11 Sprinklers shall be provided in the stuffy roof and technical mezzanine with a clearance height greater than 800mm. Sprinklers may not be provided when the following conditions are met at the same time: Protection; 2 duct insulation materials are made of non-combustible and non-combustible materials; 3 no other combustibles. According to these two points, the maximum area protected by the system in terms of water spray intensity during a fire is considered. The sprinklers below the mechanical three-dimensional garage can be excluded, and the water consumption of the spray is still 30L / S.
There is also a point of view to support measures and manual practices. According to 9.1.6, a warehouse with built-in sprinklers in the shelf should be designed with the sprinkler under the roof and the sprinkler with built-in sprinkler separately. The design flow of the system should be determined according to the sum of its design flow. . The double-layer mechanical garage has a spray water consumption of more than 30L / S, then the double-layer garage is 40 ~ 45L / S, and the three-level and above garages are 50 ~ 60L / S.
It can be seen that the spray water volume calculated by these two viewpoints is very different. When the design is affected by the beam or the arrangement is too dense, the flow in the active area may increase. For safety reasons, the double-deck garage is preferable at the planning stage. Around 50L / S, three floors and above can take about 65L / S to determine the volume of the fire fighting pool. It is also hoped that in the future specifications or standards, the spray water consumption of the mechanical three-dimensional garage will be clarified and unified design.
References:
1.GB50067-2014 “Code for Fire Protection Design of Garages, Garages and Parking Lots”
2.China National Architectural Standards Design and Research Institute. Technical Measures for Designing Civil Buildings (Water Supply and Drainage). Beijing: China Planning Press, 2009
3. Huang Xiaojia, Jiang Wenyuan. Manual of Sprinkler System Design. China Construction Industry Press, 2002
4.GB50084-2007 design specification for sprinkler system
5. Li Yunhe, “Reconsideration on the Determination of the Designed Sprinkling Water for Buildings Containing Three-Dimensional Parking Garage”
6. Sang Songbiao, Wang Jinghua, Gong Zengrong, “Discussion on Spray Water Consumption in Underground Mechanical Parking”

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