Method for evaluating effectiveness of automatic sprinkler system for low-temperature warehouse

Abstract

The invention discloses a method for evaluating effectiveness of an automatic sprinkler system for a low-temperature warehouse, which comprises the following steps of: measuring basic building information of the low-temperature warehouse, and designing and arranging related equipment of the automatic sprinkler system and an automatic fire alarm system. Water distribution pipe network water filling time, nozzle starting time and fire detection device response time are confirmed and analyzed, and the relation among the water filling time, the starting time, the response time and linkage time is evaluated; and establishing effectiveness evaluation indexes and judgment conditions of the automatic sprinkler system, carrying out effectiveness evaluation technical analysis of the automatic sprinkler system, and finally judging the rationality of the application technical scheme of the automatic sprinkler system. According to the method, all links in the working process of the automatic sprinkler system for the low-temperature warehouse are comprehensively considered, all-directional evaluation indexes of the effectiveness of the automatic sprinkler system are established, and the blank that the reasonability of the application technical scheme of the automatic sprinkler system for the low-temperature warehouse is not judged is filled.

Description

Technical Field

[0001] The present invention relates to the evaluation of the effectiveness of automatic sprinkler systems, and particularly to an evaluation method for the effectiveness of automatic sprinkler systems used in low-temperature warehouses. Background Art

[0002] Once a fire breaks out in a low-temperature warehouse, the role of the automatic sprinkler system should be fully utilized to enable timely and effective control and extinguishment of the fire in the initial stage. Compared with civil buildings and industrial factories, the application technology of automatic sprinkler systems in low-temperature warehouses is relatively complex. In addition to being related to the fire risk level and environmental conditions, it is also closely related to environmental temperature, the clear height of the warehouse, the storage height, the storage method, the type of shelves, etc. Reasonable design of the automatic sprinkler system is of great significance for ensuring the effective prevention and control of fires in the initial stage and reducing property losses and secondary disasters.

[0003] In current national standards such as the General Code for Fire Protection Facilities GB 55036-2022 and the Design Code for Automatic Sprinkler Systems GB 50084-2017, although the selection of automatic sprinkler systems for different places and the application technical requirements for protecting warehouse places are specified, there is still a lack of overall regulations for some warehouses in low-temperature regions (such as seasonal low-temperature regions, constant low-temperature regions) and the setting requirements of automatic sprinkler systems with special application sprinklers in warehouse types. For example, according to the above code requirements, when ESFR sprinklers are used in a warehouse, the system should be a wet system; for low-temperature warehouses, the indoor minimum temperature is generally lower than 4°C, and it is not suitable to use ESFR automatic sprinkler systems; when using the electric tracing method for heat preservation, there are defects such as high energy consumption and many risk hazards; when adding heating facilities, the operating cost increases greatly, which is not conducive to the national development strategy of energy conservation, environmental protection, and green and low-carbon emission reduction.

[0004] Therefore, it is necessary to establish an evaluation method for the effectiveness of the setting of automatic sprinkler systems for low-temperature warehouses, and confirm the rationality of the application technical scheme of the automatic sprinkler system according to the evaluation results, so as to improve the level of initial fire prevention and control for low-temperature warehouses. Summary of the Invention

[0005] The purpose of the present invention is to provide an evaluation method for the effectiveness of automatic sprinkler systems used in low-temperature warehouses, so as to fill the blank of the lack of effectiveness evaluation of automatic sprinkler systems set in low-temperature warehouse places, and solve the drawbacks that some technical measures without effectiveness evaluation are applied and there are greater potential safety hazards.

[0006] The present invention determines the basic building information related to a low-temperature warehouse, designs and arranges the relevant equipment of the automatic sprinkler system and the automatic fire alarm system, conducts a confirmation analysis on the water filling time of the distribution pipe network, the sprinkler activation time, and the response time of the fire detection device, and evaluates the relationship among the water filling time, the activation time, the response time, and the linkage time; establishes the effectiveness evaluation index and determination conditions of the automatic sprinkler system, conducts a technical analysis on the effectiveness evaluation of the automatic sprinkler system, and finally determines the rationality of the application technical solution of the automatic sprinkler system.

[0007] To achieve the above object, the technical solution adopted by the present invention is: An evaluation method for the effectiveness of an automatic sprinkler system for a low-temperature warehouse includes the following steps: Step 1: Collect, survey, and confirm the basic building information related to the low-temperature warehouse and the fire risk of the stored items.

[0008] Step 2: According to the basic building information of the low-temperature warehouse, design and arrange the distribution pipe network of the automatic sprinkler system, the sprinklers, and the fire detection devices of the automatic fire alarm system.

[0009] Step 3: Use fluid mechanics calculation software, input the information of the distribution pipe network of the automatic sprinkler system and the water supply equipment information, and conduct a confirmation analysis on the water filling time t1 of the distribution pipe network under different water supply modes.

[0010] Step 4: Use fire dynamics calculation software, input the information parameters of the sprinklers and the fire detection devices, and conduct a confirmation analysis on the sprinkler activation time t2 and the fire detection device response time t3 under different fire conditions.

[0011] Step 5: According to the analysis results of Step 3 and Step 4, evaluate whether the water filling time t1 of the distribution pipe network, the sprinkler activation time t2, the fire detection device response time t3, and the linkage time t4 satisfy the relationship t2≥t1+t3+t4; if the relationship is satisfied, proceed to Step 6; if the relationship is not satisfied, return to Step 2.

[0012] Step 6: Use fire dynamics calculation software and input the condition information; the condition information includes: the basic building information related to the low-temperature warehouse, the fire risk of the stored items, the basic information of the automatic sprinkler system and the automatic fire alarm system, analyze the variation law of the key performance indicators of the fire flow field in the low-temperature warehouse building, and establish the effectiveness evaluation index and determination conditions of the fire flow field before and after the activation of the automatic sprinkler system; if the determination conditions are met, proceed to Step 7; if the determination conditions are not met, modify the input condition information.

[0013] Step 7: Based on the condition information input in Step 6, determine the effectiveness of the automatic sprinkler system for the low-temperature warehouse, and further determine the rationality of the application technical solution of the automatic sprinkler system for the low-temperature warehouse.

[0014] In step three of the present invention, the water filling time t1 of the water distribution network is determined by considering multiple influencing factors such as the conversion time of the fire pump from zero flow to rated flow, the gas pressure in the network, the network slope, wave velocity, the number of end sprinkler heads opened, and the hydraulic resistance loss.

[0015] In step four of the present invention, when calculating the sprinkler start-up time t2, the sprinkler response time index, nominal operating temperature, and fire occurrence location are comprehensively considered; when calculating the response time t3 of the fire detection device, the response threshold of the fire detector, fire sensitivity, and fire occurrence location are comprehensively considered.

[0016] In step six of the present invention, the effectiveness evaluation indicators include: sprinkler opening time, number of opened sprinklers, temperature in the low-temperature warehouse, heat release rate of the goods fire, heat radiation intensity, amount of goods burned, and fire spread situation.

[0017] The determination conditions are as follows: A. If the number of opened sprinklers is less than or equal to 6, it is effective; otherwise, it is ineffective; B. If the fire does not spread to the target shelf, it is effective; otherwise, it is ineffective; C. If the temperature and heat release rate of the fire do not continue to increase after the automatic sprinkler system is activated, it is effective; otherwise, it is ineffective; D. If there is no phenomenon of sprinkler jumping open, it is effective; otherwise, it is ineffective.

[0018] The beneficial effects of the present invention are: the evaluation method is simple, reliable, reasonable, feasible, and easy to understand, and the calculation software used is all open-source software. Compared with the prior art, the present invention comprehensively considers each link in the working process of the automatic sprinkler system for low-temperature warehouses, establishes an all-round evaluation index for the effectiveness of the automatic sprinkler system, and fills the blank of the lack of determination of the rationality of the application technical solution of the current automatic sprinkler system for low-temperature warehouses. Description of the Drawings

[0019] Figure 1 is a flow chart of the method for evaluating the effectiveness of the automatic sprinkler system for low-temperature warehouses according to the present invention. Detailed Embodiments

[0020] The following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings, so that the advantages and features of the present invention are more easily understood by those skilled in the art.

[0021] Embodiment: Refer to Figure 1 , step one, collect, survey, and confirm the basic building information of the low-temperature warehouse and the fire risk of the stored items.

[0022] In this embodiment, the low-temperature warehouse is single-story, with a floor area of 12000m 2 , the fire risk is category C, item 2, and the area of each fire compartment is 2000m2 。

[0023] Step 2: According to the basic building information of the low-temperature warehouse, design and arrange the distribution pipe network, sprinkler heads of the automatic sprinkler fire extinguishing system, and fire detection devices of the automatic fire alarm system.

[0024] According to the provisions of the current national standard "Code for Design of Automatic Sprinkler Systems" GB50084-2017, in this embodiment, the automatic sprinkler fire extinguishing system in each fire compartment of the low-temperature warehouse is divided into two zones. The diameter of the main distribution pipe is DN250, the diameter of the distribution pipe is DN200, and the diameters of the distribution branches are DN65 and DN50 respectively; K-363 sprinkler heads with a flow coefficient are installed under the distribution branches, the spacing between the sprinkler heads is 2.5m - 2.8m, and the working pressure is 0.10MPa; the fire detection devices of the automatic fire alarm system adopt line-type beam smoke fire detectors, and the transmitting end and the receiving end are respectively installed 0.3m below the suspended ceiling board and wall-mounted.

[0025] Step 3: Use fluid mechanics calculation software, input the information of the distribution pipe network of the automatic sprinkler fire extinguishing system and the information of the water supply equipment, and conduct a confirmation analysis on the water filling time t1 of the distribution pipe network under different water supply modes. The water filling time t1 of the distribution pipe network is determined by considering multiple influencing factors such as the conversion time of the fire pump from zero flow to rated flow, the gas pressure in the pipe network, the pipe network slope, wave velocity, the number of end sprinkler heads opened, and the hydraulic resistance loss.

[0026] In this embodiment, the information of the distribution pipe network of the automatic sprinkler fire extinguishing system and the information of the water supply equipment are placed into the FLomaster hydraulic calculation model, comprehensively considering the conversion time of the fire pump from zero flow to rated flow, the gas pressure in the pipe network, the pipe network slope, wave velocity, the number of end sprinkler heads opened, and the hydraulic resistance loss. According to the calculation and analysis, under the layout of this distribution pipe network, the water filling time t1 of the distribution pipe network is 39.5s.

[0027] Step 4: Use fire dynamics calculation software, input the information parameters of the sprinkler heads and fire detection devices, and conduct a confirmation analysis on the sprinkler start-up time t2 and the fire detection device response time t3 under different fire conditions. When calculating the sprinkler start-up time t2, comprehensively consider the sprinkler response time index, nominal operating temperature, and the location of the fire occurrence; when calculating the fire detection device response time t3, comprehensively consider the response threshold of the fire detector, fire sensitivity, and the location of the fire occurrence.

[0028] In this embodiment, a fire dynamics model of this fire compartment is established using the fire dynamics calculation software FDS, input the performance parameters of the automatic sprinkler fire extinguishing system and the automatic fire alarm system (see Table 1), and consider different fire occurrence locations. The calculated start-up time t2 of the sprinkler heads and the response time t3 of the line-type beam smoke fire detectors under each condition are 101 - 112s and 28 - 39s respectively.

[0029] Table 1 Performance Parameters of Automatic Sprinkler Systems and Automatic Fire Alarm Systems

[0030] Step 5: According to the analysis results of Step 3 and Step 4, evaluate whether the water filling time t1 of the distribution pipe network, the sprinkler activation time t2, the response time t3 of the fire detection device, and the linkage time t4 satisfy the relationship t2 ≥ t1 + t3 + t4; if the relationship is satisfied, proceed to Step 6; if the relationship is not satisfied, return to Step 2.

[0031] In this embodiment, according to the calculation results of Step 3 and Step 4, under various working conditions, the water filling time t1 of the distribution pipe network, the sprinkler activation time t2, the response time t3 of the fire detection device, and the linkage time t4 satisfy the relationship t2 ≥ t1 + t3 + t4 (according to the provisions of the national standard "Code for Design of Automatic Fire Alarm Systems" GB50116 - 2013, t4 is taken as 3 s).

[0032] Example: If in a working condition of this embodiment, the sprinkler activation time t2 is 108 s, the response time t3 of the line - type beam smoke fire detector is 32 s, and the water filling time t1 of the distribution pipe network is 39.5 s, then t1 + t3 + t4 = 39.5 + 32 + 3 = 74.5 s, and t2 is 108 s, which is greater than 74.5 s. Therefore, this embodiment satisfies the relationship t2 ≥ t1 + t3 + t4, and the sprinkler can immediately implement water spraying for fire extinguishing after being opened.

[0033] If this embodiment does not satisfy the relationship, it is necessary to correct the influencing factors of the water filling time t1 of the distribution pipe network and make repeated corrections until it is ensured that t2 ≥ t1 + t3 + t4.

[0034] Step 6: Use fire dynamics calculation software to input condition information; the condition information includes: basic building information related to the low - temperature warehouse, fire hazard of stored goods, basic information of automatic sprinkler systems and automatic fire alarm systems, analyze the variation laws of key performance indicators of the fire flow field in the low - temperature warehouse building, and establish effectiveness evaluation indicators and judgment conditions for the fire flow field before and after the activation of the automatic sprinkler system; if the judgment conditions are met, proceed to Step 7; if the judgment conditions are not met, correct the input condition information.

[0035] The effectiveness evaluation indicators include: sprinkler opening time, number of opened sprinklers, temperature in the low - temperature warehouse, heat release rate of the goods fire, heat radiation intensity, amount of goods burned, and fire spread situation.

[0036] The judgment conditions are as follows: A. If the number of opened nozzles is less than or equal to 6, it is valid; otherwise, it is invalid. B. If the fire does not spread to the target shelves, it is valid; otherwise, it is invalid. C. If the temperature and the fire heat release rate do not continue to increase after the automatic sprinkler system is activated, it is valid; otherwise, it is invalid. D. If there is no phenomenon of the nozzles opening jumpily, it is valid; otherwise, it is invalid.

[0037] In this embodiment, the fire dynamics calculation software is used, and the input condition information is specifically shown in Table 2 to analyze the variation law of the evaluation indexes of the fire flow field in the low-temperature warehouse building. In one working condition of this embodiment, the number of opened nozzles is 5, the fire does not spread to the target shelves, and there is no phenomenon of the nozzles opening jumpily. Therefore, this embodiment meets the judgment conditions and step seven can be carried out.

[0038] Table 2 Input condition information

[0039] If this working condition of this embodiment does not meet the judgment conditions, the input condition information is corrected and step six is repeated.

[0040] Step seven: According to the condition information input in step six, judge the effectiveness of the automatic sprinkler system for low-temperature warehouses, and then judge the rationality of the application technical solution of the automatic sprinkler system for low-temperature warehouses.

[0041] The evaluation of the effectiveness of the automatic sprinkler system carried out by using the fire dynamics software FDS in this embodiment shows that when the automatic sprinkler system is activated, the fire is suppressed, and the maximum heat release rate gradually decreases. The maximum heat release rate decreases from 1.4 MW to 0.7 MW. The temperature value measured at the temperature measuring point above the fire source before the nozzles are activated gradually increases, and after activation, the temperature value measured at the temperature measuring point above the fire source gradually decreases. In this embodiment, the number of opened nozzles is less than or equal to 6, the fire does not spread to the target shelves, the temperature and the fire heat release rate do not continue to increase after the automatic sprinkler system is activated, and there is no phenomenon of the nozzles opening jumpily. It can be concluded that the automatic sprinkler system in this embodiment is effective and the application technical solution of the automatic sprinkler system is reasonable.

Claims

1. An evaluation method for the effectiveness of an automatic sprinkler fire extinguishing system for low-temperature warehouses, characterized in that, It includes the following steps: Step 1: Collect, survey and confirm the basic building information of the low-temperature warehouse and the fire risk of the stored items; Step 2: Design and arrange the distribution pipe network, sprinkler heads of the automatic sprinkler system and the fire detection devices of the fire automatic alarm system according to the basic building information of the low-temperature warehouse; Step 3: Use fluid mechanics calculation software, input the information of the distribution pipe network and water supply equipment of the automatic sprinkler system, and conduct a confirmation analysis on the water filling time t1 of the distribution pipe network under different water supply modes; Step 4: Use fire dynamics calculation software, input the information parameters of the sprinkler heads and fire detection devices, and conduct a confirmation analysis on the sprinkler head activation time t2 and the fire detection device response time t3 under different fire conditions; Step 5: According to the analysis results of Step 3 and Step 4, evaluate whether the water filling time t1 of the distribution pipe network, the sprinkler head activation time t2, the fire detection device response time t3 and the linkage time t4 satisfy the relationship t2≥t1+t3+t4; if the relationship is satisfied, proceed to Step 6; If the relationship is not satisfied, return to Step 2; Step 6: Use fire dynamics calculation software and input the condition information; the condition information includes: the basic building information of the low-temperature warehouse involved, the fire risk of the stored items, the basic information of the automatic sprinkler system and the fire automatic alarm system, analyze the change rules of the key performance indicators of the fire flow field in the low-temperature warehouse building, and establish the effectiveness evaluation indicators and judgment conditions of the fire flow field before and after the activation of the automatic sprinkler system; if the judgment conditions are met, proceed to Step 7; if the judgment conditions are not met, modify the input condition information; Step 7: Based on the condition information input in Step 6, determine the effectiveness of the automatic sprinkler system for the low-temperature warehouse involved, and then determine the rationality of the application technical scheme of the automatic sprinkler system for the low-temperature warehouse involved.

2. The evaluation method for the effectiveness of an automatic sprinkler extinguishing system for low-temperature warehouses according to claim 1, characterized in that In Step 3, the water filling time t1 of the distribution pipe network is determined by considering multiple influencing factors such as the conversion time of the fire pump from zero flow to rated flow, the gas pressure and pipe slope in the pipe network, the wave velocity, the number of end sprinkler heads opened, and the hydraulic resistance loss.

3. An evaluation method for the effectiveness of an automatic sprinkler fire extinguishing system for low-temperature warehouses according to claim 1, characterized in that, In Step 4, when calculating the sprinkler head activation time t2, comprehensively consider the sprinkler head response time index, the nominal operating temperature, and the fire occurrence location.

4. An evaluation method for the effectiveness of an automatic sprinkler fire extinguishing system for low-temperature warehouses according to claim 1, characterized in that, In Step 4, when calculating the fire detection device response time t3, comprehensively consider the response threshold of the fire detector, the fire sensitivity, and the fire occurrence location.

5. The evaluation method for the effectiveness of an automatic sprinkler fire extinguishing system for a low-temperature warehouse according to claim 1, wherein, In Step 6, the effectiveness evaluation indicators include: the sprinkler head opening time, the number of opened sprinkler heads, the temperature in the low-temperature warehouse, the heat release rate of the goods fire, the heat radiation intensity, the amount of goods burned, and the fire spread situation.

6. The evaluation method for the effectiveness of an automatic sprinkler fire extinguishing system for low-temperature warehouses according to claim 1, characterized in that In Step 6, the judgment conditions are as follows: A. If the number of opened sprinkler heads is less than or equal to 6, it is effective; otherwise, it is ineffective; B. If the fire does not spread to the target shelf, it is effective; otherwise, it is ineffective; C. If the temperature and the fire heat release rate do not continue to increase after the activation of the automatic sprinkler system, it is effective; otherwise, it is ineffective; D. If there is no phenomenon of the sprinkler head jumping open, it is effective; otherwise, it is ineffective.

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