泄压阀、紧急关闭阀和紧急开启阀的应用

泄压阀、紧急关闭阀和紧急开启阀的应用

2010-03-08 14:50:01 阅读5 评论0 字号:

译文:
泄压阀、紧急关闭阀和紧急开启阀是近年来研制并应用的阀门,备受建筑和消防给水界的关注。  1 泄压阀   泄压阀设置在消防水泵出水管上,平时关闭,在消防给水管网压力超过设定值时自动开启,以防止给水系统因超压而损坏。   消防给水管网的超压主要是由于以下原因:①按消防设计流量选用水泵的流量—扬程曲线属于陡峭型,在小流量运行时(自检或火灾初期)会出现超压;②水泵突然因故(如停电)停转,出水管又未采取相应技术措施,停泵水锤造成超压。   泄压阀设置应注意位置、口径选择、压力设定和相应附件配置等问题。   ①泄压阀可设在消防水泵附近或消防水箱附近。自动喷水灭火系统设计规范》GBH84—1985修订本送审稿10.3.3条规定要求:“每组水泵……出水管应设控制阀……,必要时应设泄压阀。”该条文在报批稿中被改为:“……必要时,应采取控制供水泵出口压力的措施。”这些措施即包括泄压阀。   当泄压阀设置在消防水泵出水管上时,可设在止回阀前、后。设在止回阀前能消解水泵小流量运行所造成的超压,而设在止回阀后(沿水流方向)不仅可消解因水泵小流量运行而造成的超压,还可消解由停泵水锤造成的超压,即使消防水泵出水管未采取其他 xx停泵水锤的措施(速闭式止回阀、缓闭式止回阀、缓冲罐等),也不致造成危害和损失。   ②泄压阀口径有两种做法,一种是与消防给水总管同径或小一级,另一种是采用DN100或DN150的泄压阀。   从泄压的角度讲,泄压阀的口径越大泄压越快、效果越好。如图1所示,Q为泄流量,泄压阀的口径大,Q值就大,RBC曲线偏向右侧,R曲线与H曲线相交点M也会右移,其压力值随之降低。但从经济角度看,口径越大,泄压阀价格越高,必然增加工程建设费用。因而从实际出发,目前倾向于采用固定口径的 泄压阀,即使泄压时实际压力值会稍大于大口径泄压阀泄压的实际压力值,但综合效果还是可行的。因此,泄压阀口径可作如下规定:若消防给水总管管径D≤150mm,则采用 DN100的泄压阀;若消防给水总管管径D>150mm,则采用DN150的泄压阀。   ③泄压阀的压力设定值应高于消防主泵和稳压泵的压力设定值。当有稳压泵时,启动和关闭稳压泵存在两个压力值(指稳压泵运行时的压力值)。稳压泵的停泵水锤压力容易造成泄压阀误开启,因此对于稳高压消防给水系统应有完善可靠的xx停泵水锤的技术措施,并应复 核消防给水管网在水锤产生后的残余压力,若低于泄压阀的压力设定值,才可确保不致误开启。   ④泄压阀应设置在与消防给水总管连接的支管上。为方便泄压阀检修及防止控制阀误关闭,在泄压阀前应设信号闸阀或信号蝶阀。为保持泄压阀维修时水流畅通,应设置旁通管。   2 紧急关闭阀   紧急关闭阀平时开启,在管网压力超过压力设定值时自动关闭,以防止消防水泵运行时消防用水进入水箱,同时可防止在消防水泵运行时,生活—消防共用给水系统中生活给水配件因超压而损坏。   我国推荐生活和消防共用的给水系统。这类系统平时启动生活水泵的压力值较低,火灾时启动消防水泵的压力值远高于启动生活水泵时的压力值,而按《建筑设计防火规范》第8.6.3条第四款规定:“发生火灾后,由消防水泵供给的消防用水不应进入消防水箱。”为解决这一问题,应在进入消防水箱的管道上设置紧急关闭阀(如图2)。同时为防止消防水泵启动时生活给水配件超压,应在生活给水总管上设置紧急关闭阀。   紧急关闭阀的问题是压力设定。若压力设定过低,生活水泵启动时紧急关闭阀也会关闭;若压力设定过高,消防水泵启动时紧急关闭阀不关闭。一般,其压力设定值应高于生活水泵零流量时的压力值,低于消防水泵设计流量值时的压力值。同时在给水总管上必须采取可靠的技术措施以防止产生水锤。   3 紧急开启阀   紧急开启阀应用于水喷雾灭火系统,目前尚未在工程中实施。紧急开启阀平时关闭,在管网 压力达到压力设定值时自动开启通水,目的是防止水喷雾灭火系统在消防水泵达到额定转速 前因压力偏低而出现的水喷淋现象。   消防给水管道设置的阀门以常开的为多,而紧急开启阀要求常闭,即在消防水泵启动后达到 额定转速,管网压力达到设计要求压力值时才开启,这就要求阀门的启闭正常、可靠。紧急 开启阀性质与泄压阀相近,都在达到压力值时开启,不同之处在于泄压阀开启后,水流排放或回流至消防水池以泄压;紧急开启阀开启后,水流进入水喷雾灭火系统用于灭火。两者都属于水力控制阀范畴,都设置有用于先导的针阀,而针阀易因杂质堵塞而不能动作;都有用于控制阀瓣动作的隔膜,隔膜为橡胶材质、易老化、磨损。对这两个部件采取的相应措施是 :①在针阀前设置多级过滤器,过滤器滤网孔目逐级缩小,以截留固体颗粒杂质;②橡胶隔膜采用优质产品,并定期检查隔膜和水力控制阀内弹簧的情况。   目前泄压阀、紧急关闭阀和紧急开启阀都作为通用阀门对待,而未列入消防专用阀门范畴,不需通过消防产品质量监督检验测试中心检测。笔者认为这种情况应予改变,泄压阀、紧急 关闭阀和紧急开启阀都只用于消防给水系统,应尽快将其纳入消防专用产品的范畴。

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原文:
Pressure relief valves, emergency shut-off valve and emergency open valve is developed and applied in recent years, valves, much building and fire water supply circles. A pressure relief valve Fire pump pressure relief valve installed in the outlet pipe, normally closed, the fire water supply network when the pressure exceeds a set value automatically open to prevent the water supply system damaged due to overpressure. Fire to the water distribution network over-pressure is mainly due to the following reasons: ① design flow selected by the fire pump flow - lift curves are steep type, run-time in a small flow rate (initial self-test or fire) will appear over-pressure; ② pump suddenly due to Therefore, (such as electricity) stop switch, outlet pipe has failed to take appropriate technical measures to stop pumping the water hammer caused by overpressure. Pressure relief valve setting should pay attention to location, caliber selection, pressure set and the corresponding attachment configuration and other issues. ① pressure relief valve may be located in the vicinity of the fire pump and fire water tanks in the vicinity. Automatic sprinkler system design specifications "GBH84-1985 revised manuscript requirements specified in Article 10.3.3:" Each pump outlet pipe ... ... ... ... should be set up control valve, if necessary, pressure relief valves should be located. "The provision In the Draft for Approval were as follows: "... ... when necessary, should be taken to control the pump outlet pressure for the measure." These measures which includes the pressure relief valve. When the pressure relief valve is set when the fire pump outlet pipe can be located in the valve before and after. Check prior to digestion in the small water pump flow rate caused by overpressure operation, while located in the valve later (along the flow direction) can not only run the digestion due to low flow rate pump caused by excess pressure, but also digestion by stopping pump water hammer caused by excess pressure, even if the fire pump outlet pipe failed to take other means of eliminating water hammer pump shut down measures (speed closed-valve, relief valve closed, the buffer tank, etc.), it will not cause harm and losses. ② pressure relief valve bore there are two ways one is with the fire water mains with diameter or a small one, and the other is used for pressure relief valve DN100 or DN150. From the point of view of pressure relief, pressure relief valve diameter greater pressure relief sooner, the better. Shown in Figure 1, Q for the vent flow, large diameter pressure relief valve, Q value is large, RBC curves tend to the right, R curve and the H curve of intersection of M will be shifted to the right, its pressure is reduced. However, from an economic point of view, the larger diameter, pressure relief valves to higher prices, will increase construction costs. Therefore proceed from reality, the current preference for a fixed diameter of the pressure relief valves, pressure relief even when the actual pressure value when the large-diameter slightly larger than the actual pressure relief valve pressure relief value, but the combined effect is still feasible. Therefore, the pressure relief valve diameter can be used for the following provisions: If the fire water mains pipe diameter D ≤ 150mm, then the use of the pressure relief valve DN100; if the fire water mains pipe diameter D> 150mm, then the use of the pressure relief valve DN150. ③ the pressure relief valve setting should be higher than the main fire pumps and pump pressure regulator setting. When a regulator pump, pump start and shut down regulator, there are two pressure values (defined as the pressure regulator pump run-time value). Regulator pump stopped pumping the water hammer pressure easily lead to false pressure relief valve to open, so for the stable high-pressure fire water supply system should be comprehensive and reliable elimination of water hammer pump shut down the technical measures, and should review the fire water distribution network after the election in the water hammer The residual pressure, if less than the pressure relief valve setting in order to ensure that no mistake to open. ④ relief valve should be set up with the fire water mains connected to branch pipe. To facilitate maintenance and prevention of pressure relief valves control valve mistakenly closed, the pressure relief valve should be set before the signal or signal butterfly valve. In order to maintain smooth water flow pressure relief valve repair, bypass pipe should be set. 2 emergency shutdown valves Emergency shutdown valve normally open, the pressure in the pipe network pressure exceeds set value automatically shut down to prevent the fire pump to run water into the tank when the fire at the same time to prevent the fire pump run-time, life - to live in the fire water supply system shared water supply fittings for overpressure damage. My recommendation shared life and fire water supply system. Such systems usually start the life of the pump pressure is low, fire, fire pump starts when the pressure is much higher than the life of pump starts when the pressure value, while the "architectural design code for fire protection" Article 8.6.3 by stipulating: "After the fire, from fire water pump fire water supply should not enter the fire service water tanks." To resolve this problem, should enter the fire service water tanks set up the pipeline emergency shutdown valve (Figure 2). At the same time to prevent the fire pump starts when the life of water supply fittings overpressure should be set up in the life of water mains emergency shutdown valve. Emergency shut-off valve problem is that the pressure setting. If the pressure set too low, life starts when the pump will close the emergency shutdown valve; if the pressure set too high, when the emergency fire pump to start off valve is not closed. General, the pressure set value should be higher than the life of pump flow to zero pressure value, lower than the value of fire pump design flow when the pressure value. At the same time in the water mains must be taken to reliable technical measures to prevent the generation of water hammer. 3 Emergency Open valve Emergency Open valve used in water spray fire-extinguishing systems, has yet to be implemented in engineering. Emergency Open valve normally closed, the pressure in the pipe network to automatically open when the pressure set value pass water, to prevent water spray fire-extinguishing system in the fire pump to reach the rated speed ago the emergence of low pressure water spray phenomenon. Fire water supply pipeline is set to always open the valve for the more regular and urgent demands to open valves closed, that is, the fire pump starts to reach the rated speed, pipe network pressure to meet the design requirements when the pressure value to open, which requires the valve open and close properly and reliable. Emergency pressure relief valves to open and close valves in nature, are open when the pressure value is reached, the difference is that the pressure relief valve opens, water discharge or fire back to the pool in order to pressure relief; emergency open valve opens, water flows into the water spray fire-extinguishing system for fire fighting. Both of which are areas of hydraulic control valves are used for the pilot to set the needle valve, while the needle can not be easily blocked by impurities in action; are used to control the movement of the diaphragm flap valve, diaphragm of rubber material, easy to aging, wear and tear. These two components take the corresponding measures are: ① in the needle pre-set multi-stage filter, filter mesh filter Kong progressively reduced, in order to retain solid particles of impurities; ② rubber diaphragm with high-quality products, and regularly check the diaphragm and the hydraulic control valve spring situation. At present pressure relief valves, emergency shut-off valve and emergency valve to open valves are treated as a general-purpose, special valves are not covered in fire areas, do not pass through the fire Product Quality Supervision and Testing Center for testing. I believe that this situation should be changed, pressure relief valves, emergency shut-off valve and emergency valve to open only for fire-fighting water supply system, should be included as soon as the fire-specific product areas.
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