1. Hydrant water supply system 1.2 The level of fire hydrant Domestic fire hydrant DN65, DN50, and DN253 specifications, DN25 hose can not be used alone, only with DN65 and DN50. NEPA14 fire hydrant is divided into three levels: â… grade DN65 fire hydrants, only the bolt mouth; â…¡ level DN40 fire hydrant box, with a hose and water gun fire hydrant, for light hazard level place DN25 can be used for the hose; â…¢ grade DN65 bolt mouth and DN40 fire hydrant box, for light hazard level place, DN40 fire hydrant box can be changed to DN25 hose; with automatic sprinkler system place, no DN40 fire hydrant box. At present, our basic DN50 fire hydrant does not, DN40 hydrant does not, DN25 can not be used alone hose. DN65 fire hydrant professional firefighters and non-professional firefighters are available. In the United States DN65 fire hydrant only for professional firefighters. Therefore, DN40, DN25 fire hydrant self-help fire hydrant. 1.3, the location of the fire hydrant, setting and bolt pressure China's "Construction Regulations" and "High Regulations" provides that the fire hydrant is located in the walkway, near the stairs and other obvious easy access. Fire hydrant spacing: high for 30m, multi-layer 50m, the length of the hose 20m-25m. Fire elevator front room fire hydrant, roof set test fire hydrant. Fire hydrant throat height of 1.1m, the United States NF-PA14 provides: (1) fire hydrant riser is the fire hydrant (due to the absence of totes and hoses) should not pass through dangerous areas should be located to prevent mechanical damage and (2) The riser riser and water supply riser riser shall be located in a closed stairwell or in an equivalent fire-proof position to a closed stairwell; (3) The fire hydrant riser of a dry system shall not be enclosed in a building Within the wall or wall bolt; (4) fire hydrant should be placed without obstructions, 0.9m-1.5m from the location. If equipped with automatic sprinkler system, the edge of the supervisor may not consider the protection, to DN40 fire hydrant riser can not consider the protection. DN65 fire hydrants shall be located at the following locations: (a) intermediate stairway platforms for each staircase; (b) horizontal exits adjacent either side of the wall; (c) at the exit of each corridor from the building into the corridor; (d) (E) Setting of the most unfavorable point test fire hydrant on the middle stairway to the top of the roof; (f) ) The maximum distance between the unfavorable point on the floor without automatic sprinkler system and the fire hydrant shall not exceed 45.7m. The maximum distance between the unfavorable point on the floor with automatic sprinkler system and the fire hydrant shall not exceed 61m. For the setting level â…¡ DN40 hydrant building: any part of it to the fire hydrant distance of not more than 39.7m. Fire hydrant less than DN40 is not more than 36.6m. This fire hydrant set up and evacuation distance quite easy to understand. China's "Regulations" provides that the civil building room to the stairs evacuation distance of 20m-40m, with automatic sprinkler system can increase the evacuation distance 25%, an increase of 10m. The straight line distance from the door of the room to the nearest point in the room is 15m. If the DN65 fire hydrant is set in the stairwell, the maximum distance between the floor and the fire hydrant should not exceed 55m, and 65m when the automatic sprinkler system is installed. "High regulation" provisions of the evacuation distance and "build rules" the same. So if China's norms DN65 fire hydrant set in the stairwell, fire hydrant arrangement and the United States norms. 1.4, Hydrant Hydrant Hydrant Excess Pressure Our "Hydrometallurgical Hydrochloric Acid" and "Hydrazine Hydrochloride" regulations stipulate that the pressure of hydrant hydrant should be less than 0.50Mpa. Fire hydrant water column for the enrichment of 7m, 10m, 13m, enriched water column corresponding to the minimum hydrant water pressure is 16m, 19m, 22m. NFPA14 provides: DN65 hydrant bolt mouth maximum and minimum residual pressure of 0.69Mpa, for DN40 and DN25 hydrant maximum minimum residual pressure of 0.45Mpa, indicating that the United States norms on the fire hydrant outlet pressure is very important, hydrant bolt mouth pressure constant Value, greater than this value can be set decompression device, usually decompression regulator fire hydrant. 1.5, fire hydrant system China's "high regulation" Article 7.1.3 provides indoor fire water should be high pressure or temporary high-pressure water supply system, "Construction Regulations" Article 8.6.1 provides for non-heating plant in cold areas, the storehouse indoor fire hydrant system, Can be used dry system. 1.6, the fire hydrant design flow "high regulation" provides that the design of high-rise building indoor fire hydrant flow rate of 20L / S-40L / S, "Construction Regulations" provides civil design indoor fire hydrant design flow of 5L / S-30L / S, outdoor fire water For the 10L / S-30L / S; warehouse design flow of 5L / S-40L / S; outdoor fire water is 10L / S-45L / S. Design fire duration, A, B, C warehouse 3h, a high-rise building 3h, the other for 2h. 2, fire water supply system regulator pump Fire water supply system is the pressure of the system to maintain the pressure of the pump, the system plays a guardianship and the system has the function of automatic control. The pressure of the pump can be determined according to the system pressure. The pressure of the pump can be determined according to the system pressure. The pressure of the pump is higher than that of the main pump by 0.1Mpa-0.2Mpa, or the pressure of the pump is the main pump 1.1 times -1.2 times. But for the regulation of pump flow to have a different view. "High regulation" Article 7.4.8 supercharging facilities shall meet the following requirements: fire hydrant water supply system should not exceed 5L / S; for automatic sprinkler system should not exceed 1L / S. The United States NFPA20 "StandandfortheInstallationofCentrifugalFirePumps" (1996Edition) provides pressure pump (PressureMaintenanPumps / JoceyPumps / Make-UpPumps) flow of not less than the normal system of leakage, the pressure should be sufficient to maintain the system pressure. Obviously, our country has stipulated the upper limit of the flow of the steady pressure pump, and the United States has stipulated the lower limit of the steady pressure pump. The pressure setting of our country's regulated pump is to meet the water consumption of a fire fighting unit. The United States is the system's leakage water. 3, fire pump NFPA20 fire pump performance requirements are as follows: Pump out of the flow rate of 150% of the selected operating point, the lift is not less than 65% of the head of the selected operating point, shut down when the pump head is not greater than 140% of the selected work point lift. The fact is that the performance of the pump curve is a smooth curve. China's standard fire pump no detailed rules, resulting in the selection of fire pumps have a lot of discrepancies. It is recommended that designers refer to the NFPA20 regulations at design time. Xmas Decoration Doll,Christmas Decor Dolls,Santa Doll,Christmas Doll Zhoushan Kaiyun Christmas Toys Co., Ltd. , https://www.kaiyuntoy.com
1.1 hydrant bolt pressure and system partition China's "Building Code for Fire Protection Design" GBJ16-87 revised edition (hereinafter referred to as "Building Regulations") 8.6.2 and "fire protection design of tall buildings" GB50045-95 (hereinafter referred to as "high Regulation ") Article 7.4.6 Hydrant Hydrant Hydrostatic pressure should not exceed 0.8Mpa, when more than 0.8Mpa should be taken to partition the water supply system.
The United States NFPA14 "StandardfortheInstallationofanpipeandHoseSystem" (1996Editon) provides that the pressure at any point in the system can not exceed 2.41Mpa at any time, when the plug at the static pressure exceeds 1.21Mpa should be set decompression device.
China Hydrant Hydrostatic pressure should not exceed 0.80Mpa is the system partition value. Hydrant static pressure requirements are given in view of the quality of hydrants - bearing pressure. China's "indoor fire hydrant" GB3445-82 provisions of the indoor fire hydrant working pressure of 1.60Mpa, test pressure of 2.40Mpa, far greater than the static pressure zone value of 0.80Mpa, so our system can be properly increased partition values. There are two values ​​in the United States system to determine the partition, one with China's equivalent Hydrant static pressure does not exceed 1.21Mpa; Second, any point of the system pressure at any time can not exceed 2.41Mpa, which is the system must be in series partition requirements. According to the survey, a lot of buildings in our country have a height of 60m-70m. The height of the building, together with the height of the basement and the height of the roof water tank, is often larger than 80m. As a result, the hydrant system is zoned to cause the fire hydrant system equipment and piping to increase Investment increased. Properly increasing this value or drawing on U.S. standards can save you a lot of money and simplify your system.
Recommended static pressure partition value 1.0Mpa-1.2Mpa, system serialization partition value 2.40Mpa. This can take full advantage of the fire hydrant bearing pressure, but also to save money.
Proposed "rules" no hydrants are provided at the premises are throat, hose can be combined with the water supply system. There are automatic sprinkler system places only DN65 hydrant bolt mouth; no automatic sprinkler set DN65 fire hydrant bolt mouth and DN25 hose. This will not only save investment, but also take into account both firefighters and non-professionals specialized fire fighting fire.
China's fire hydrant arrangement only fire elevator front room allows to set fire hydrant, while the staircase is not allowed to set the fire hydrant. The reason is that the fire hydrant located in the stairwell will destroy the sealing of the stairwell. Even if the smoke exhausting function is weakened or destroyed, it will affect the evacuation. Usually the fire hydrant is located in the corridor. Corridor fire hydrant fire without protection, and the corridor filled with flue gas, fire extinguishers are often near the fire in this layer of firefighters can not access firefighters to use this layer of fire hydrant fire or the upper and lower fire hydrant, or by Fire truck water supply, hose laying along the stairs to the fire floor. This will also destroy the smoke barrier in the closed stairwell. In fact, firefighters can only arrive within 5 minutes. At this time, if the personnel in the building are still in the building, the evacuees have already been evacuated. Those who can not evacuate may not be able to achieve the evacuation of the stairs by themselves. Therefore, the fire hydrant placed in the stairwell does not affect the function of evacuation stairs, it is recommended DN65 fire hydrant should be located in the stairwell, DN40 and DN25 self-help fire hydrant located in the corridor.
Our fire hydrants are equipped with a hose, for many years without and without maintenance, to the basic fire can not be used, firefighters use their own hoses. For this reason DN65 fire hydrants only suppository unmatched box and hose, DN40, DN25 fire hydrant box and hose set.
The minimum remaining pressure and the maximum pressure at the hydrant spout depend on the ability of the firefighters and users to withstand the reactionary thrust of the hydrant as well as the fire extinguishing requirements of the hydrant to fill the water column. China's hydrant bolt mouth maximum remaining pressure 0.50Mpa, the minimum remaining pressure of 16m, 19m, 22m. However, the minimum remaining pressure and the maximum pressure at the hydrant plug mouth in the United States are one value. The DN65 fire hydrant is 69 m and the DN65 fire hydrant is 45 m. The distance between the American fire hydrants is greater than the distance between our country. The maximum length of the water hose is 3 pieces of 25m. If the head loss of the water hose and the joint is removed, the actual pressure of the hydrant is equivalent to that of our country. Obviously, the pressure on the United States to hold its own arms is much greater than that of our country. The minimum remaining pressure is not only related to the thrust force but also to the radius of protection. The United States DN65 fire hydrant its set up and stair spacing, even in the fire hydrant riser protection, firefighters and evacuation of personnel applications. According to China's current "high regulation" and "rules" evacuation distance requirements, fire hydrant arranged in the stairwell, the fire hydrant spacing of 40m-80m, with automatic sprinkler system for the 50m-100m. Such as the hose for the 3 25m, can be a water injection to reach any part, such as the use of the same staircase between the lower and upper fire hydrant to ensure that there are two water column to reach any part.
In order to facilitate the appearance of buildings and firefighters in actual combat and with international standards, it is recommended DN65 fire hydrants only set up in the evacuation of the stairwell, the distance between the stairs and the spacing is quite, the maximum and minimum residual pressure of 0.50Mpa, so fire hydrant can be accessed 2 hose, the protection radius will be greater. DN25 hose pitch of 30m, the maximum remaining minimum pressure of 0.40Mpa.
The United States NFPA14 fire hydrant system is divided into five systems: (1) fully automatic dry system - usually the system piping is filled with compressed air and equipped with a dry-type alarm valve the same device that allows water to automatically enter the open fire hydrant, the system (2) Fully automatic wet system - The normal system piping is a water-filled wet system whose water supply can automatically supply and meet the system's required fire-fighting water volume; (3) Semi-automatic dry System - The dry pipe system is equipped with deluge valve-like devices and a remote control at each hydrant to allow water to enter the system. The system's water supply is capable of supplying and servicing the system when the remote controls operate (4) Manual dry system - the system piping is dry and there is no permanent water supply to the system, the fire fighting water needed for manual dry systems comes from the fire pump of the fire truck and water is supplied to the system through the fire pump ; (5) Manual wet system - the pipe is wet and a small flow water supply is connected to maintain the system Pressure, but the system can meet the system without permanent water supply facilities required amount of water, wet systems require manual fire fire pump water from the fire, and the water supply system through the fire pump adapter.
Obviously the "high gauge" referred to the actual high-pressure system and temporary high-pressure system are actually the United States refers to the standard automatic wet system, "built" refers to the dry system should be the United States specification refers to the automatic dry system Or semi-automatic dry system. For fully automatic dry and wet systems, the system is fully automated and provides the amount of water needed to meet the system's fire fighting as long as the fire is on. It can be seen that there is not much difference between the domestic system of hydrant system and the temporary high-pressure system. The reason is that it is hard to find a true high-pressure hydrant system, that is, the hydrant system can meet the requirements of the system fire station at any time without starting the fire pump Need water and water pressure. For this reason, it is recommended that the concept of normal high pressure system and temporary high pressure system should be canceled and new concepts such as fully automatic dry system, fully automatic wet system, semi-dry system, manual dry system and manual wet system be eliminated. In the meantime, in view of the actual situation in our country, it is suggested to adopt four systems: fully automatic dry system, fully automatic wet system, semi-automatic dry system and manual dry system. At the same time for the most important buildings with dual water source water supply system, that is, in addition to fire water and fire pump water supply, the addition of a roof tank or pressure tank water supply.
NFPA14 stipulates that the minimum flow rate of the most unfavorable fire hydrant riser of Class I and III hydrant system is 31.55 / s, and the minimum flow rate of additional riser should be 15.76 L / S per one, but the total flow should not exceed 78.85 L / S. â…¡ level fire hydrant system most unfavorable hydrostatic fire hydrant riser minimum flow of 6.32L / S, without additional flow. Class â… , â…¡, â…¢ level fire hydrant system design fire lasted 0.5h. When equipped with automatic sprinkler system fire hydrant flow can be reduced. NFPA 14 provides that for fire hydrant systems associated with automatic sprinklers, there are three levels of indoor fire hydrant water supply of 0L / S, 3.15 / S, and 6.3L / S for light, medium and high-hazard categories; When combined with indoor and outdoor fire hydrant systems, the indoor and outdoor fire hydrant water supply has a light hazard level of 6.31L / S, a medium hazard level of 15.77L / S and a serious hazard level of 31.54L / S. As a result, the design of indoor hydrant systems for buildings with automatic sprinkler systems in the United States has been greatly reduced.
Therefore, we can learn from the experience of the United States and properly reduce the water supply to the hydrant system for buildings with automatic sprinkler systems.
Automatic Sprinkler System Pipeline Leakage According to the national "Heating and Sanitation Engineering Construction and Acceptance Code," Section 3.15: When the hydraulic test, the pressure drop within 10min is not greater than 0.05Mpa. Then the test pressure dropped to the working pressure for visual inspection, to not leak as qualified. "Automatic Sprinkler System Construction and Acceptance Code," the provisions of Article 6.2.3 hydrostatic test test point should be set at the lowest point of the system pipe network, the water pipe network, the net should be drained of air and should Slowly booster, to test pressure, the regulator 30min, visual pipeline without leakage, no deformation, and the pressure drop is not greater than 0.05Mpa. "Water Supply and Drainage Pipeline Construction and Acceptance Code" GB50268-97 Section 10.2.13 stipulates: DN100 steel pipe allows water seepage is 0.28L (min & # 8226; km), DN150 steel pipe allows water seepage is 0.3L (min & # 8226 ; km). Obviously, if pipeline construction meets the national standard, there will be little leakage of water in the system pipe network. The author himself has observed two completed projects. Leakage of indoor pipes is mainly caused by capillary seepage of water at the pipe interface and leakage of test drain valves and pump outlet check valves with one end exposed to the atmosphere. Pipeline capillary leakage at the interface generally can not form a drop of water, and more in the air evaporation. One end of the valve leakage contact with the atmosphere is easy to observe, promptly shut down or replace the valve is not a problem. Pump outlet check valve due to lax and back to the pool back to the water, this phenomenon is not easy to observe, is a major hidden pipe network leakage of water. For example, a project selected pump flow of 1.33L / S, the pump also failed to run a long time the set pressure, check the pump outlet check valve is not strict and leak to the pool, replace the check valve After the regulator pump work, and start a few days. This shows that the amount of system leakage is very small, almost negligible.
According to the survey, the flow of pressure stabilizing pump at home and abroad was selected as 0.5L / S-2.0L / S. When there was no pressure tank in the system, the pump was stopped with water hammer. In view of the regulator pump system has the guardianship and automatic control requirements. We recommend that the regulator pump flow 1.0L / S-2.0L / S, the pressure is higher than the main pump 0.1Mpa-2.0Mpa or 1.1 times the main pump -1.2 times. Regulator pump is best equipped with pressure tank, if not set pressure tank, pump controller should be stamped on, so that when the pump is not stopped due to frequent water hammer and start.
"High regulation" and "built rules" on the performance of the fire pump does not require testing, NFPA20 provides fire pumps in the outlet pipe set up with a flow meter. The flow meter should be able to test 175% of the selected flow of the pump. The fire pump should be equipped with a pressure gauge with a diameter greater than 89 mm on the outlet pipe so that the pump can fully test the performance of the pump after it is installed so as to know whether it meets the design requirements. It is recommended that designers consider this issue in their design.
According to China and the United States, fire design specifications and engineering practice, the fire hydrant water supply system to discuss several issues in order to jointly promote the development of the fire service, please comment on the improper.