一、橋架起火現(xiàn)場：電纜像「烤串」一樣冒煙

　　1、 Bridge fire scene: cables smoke like "grilled skewers"

　　去年某數(shù)據(jù)中心凌晨突發(fā)火災，監(jiān)控畫面顯示：多層橋架內(nèi)電纜過熱起火，火花像煙花一樣從通風孔竄出，半小時就燒穿了屋頂。消防員發(fā)現(xiàn)：橋架內(nèi)溫度高達 600℃，電纜絕緣層熔化成黏糊糊的「黑油」—— 而這一切的罪魁禍首，竟是通風孔設計不當！

　　Last year, a data center caught fire in the early hours of the morning. The surveillance footage showed that the cables in the multi-layer cable tray were overheated and caught fire. Sparks burst out of the ventilation holes like fireworks and burned through the roof in half an hour. Firefighters discovered that the temperature inside the bridge was as high as 600 ℃, and the insulation layer of the cable melted into a sticky "black oil" - and the culprit behind all of this was actually the improper design of the ventilation holes!

　　二、散熱差為啥會起火？看電纜的「中暑過程」

　　2、 Why does poor heat dissipation cause a fire? Watching the 'heat stroke process' of cables

　　1. 多層橋架 =「密閉蒸籠」

　　1. Multi layer bridge="closed steamer"

　　橋架層數(shù)越多，空氣越難流通，就像疊放的蒸籠，底層電纜被上層「烤」得發(fā)燙；

　　The more layers a bridge has, the harder it is for air to circulate, like a stacked steamer, where the bottom cables are "baked" by the upper layers and become hot;

　　某工廠實測：3 層橋架比單層溫度高 25℃，電纜絕緣層壽命縮短 70%。

　　A factory has tested that the temperature of a three-layer bridge is 25 ℃ higher than that of a single layer, and the lifespan of the cable insulation layer is shortened by 70%.

　　2. 熱量累積 =「慢燉電纜」

　　2. Heat accumulation="slow cooking cable"

　　電流通過電纜產(chǎn)生熱量，通風差時熱量散不出去，像用小火慢燉電纜；

　　Electric current generates heat through cables, but when there is poor ventilation, the heat cannot be dissipated, like simmering cables over low heat;

　　當溫度超過 90℃，絕緣層開始軟化；超過 130℃，直接碳化起火，某倉庫火災前，橋架表面溫度曾測出 150℃。

　　When the temperature exceeds 90 ℃, the insulation layer begins to soften; Exceeding 130 ℃, it directly carbonized and caught fire. Before a warehouse fire, the surface temperature of the bridge was measured to be 150 ℃.

　　三、通風孔設計的「救命兩要素」：布局 + 孔徑

　　3、 The "life-saving two elements" of ventilation hole design: layout and aperture

　　1. 布局要像「空調(diào)出風口」

　　1. The layout should be like a 'central air conditioning outlet'

　　橫向通風孔：給電纜「扇扇子」

　　Horizontal ventilation hole: fan the cable with a fan

　　關(guān)鍵數(shù)據(jù)：孔間距≤30cm，像給橋架裝「排風扇」，某電子廠把孔間距從 50cm 改成 25cm 后，溫度降了 12℃；

　　Key data: Hole spacing ≤ 30cm. For example, when installing a "exhaust fan" on a bridge, a certain electronics factory changed the hole spacing from 50cm to 25cm, resulting in a temperature drop of 12 ℃;

　　錯誤案例：某車間橋架孔間距 80cm，相當于給電纜「戴口罩」，熱量散不出去，終引發(fā)短路。

　　Error case: The distance between the bridge holes in a certain workshop is 80cm, which is equivalent to wearing a mask on the cable, and the heat cannot be dissipated, ultimately causing a short circuit.

　　縱向通風帶：造「拔風煙囪」

　　Vertical ventilation belt: creating a "chimney for air extraction"

　　設計要點：橋架兩側(cè)開長條孔，高度≥5cm，像煙囪一樣利用熱空氣上升原理拔風；

　　Design points: Open long holes on both sides of the bridge, with a height of ≥ 5cm, and use the principle of hot air rising like a chimney to extract air;

　　實測效果：某變電站加了縱向通風帶后，熱空氣排出速度提升 40%，相當于給橋架裝了「抽油煙機」。

　　Actual test results: After adding longitudinal ventilation belts to a certain substation, the speed of hot air discharge increased by 40%, which is equivalent to installing a "range hood" on the bridge.

　　2. 孔徑大小 =「窗戶尺寸」

　　2. Aperture size="window size"

　　圓孔：直徑≥10mm 才夠用

　　Circular hole: diameter ≥ 10mm is sufficient for use

　　小于 10mm 的孔像「針孔」，風根本吹不進去，某機房換了 15mm 孔徑后，風速從 0.5m/s 升到 1.8m/s；

　　Holes smaller than 10mm look like "pinholes", and the wind cannot blow in at all. After changing the 15mm aperture in a certain computer room, the wind speed increased from 0.5m/s to 1.8m/s;

　　類比：10mm 孔相當于開紗窗，15mm 才像開窗戶，通風量差 3 倍。

　　Analogy: A 10mm hole is equivalent to opening a screen window, while a 15mm hole is like opening a window, with a ventilation difference of three times.

　　長孔：寬度≥5mm 防積灰

　　Long hole: Width ≥ 5mm to prevent dust accumulation

　　寬度太小容易被灰塵堵住，某工廠用 3mm 寬的長孔，半年就積滿灰，相當于「通風孔變堵孔」；

　　If the width is too small, it is easy to be blocked by dust. A factory used a 3mm wide long hole, which accumulated dust in half a year, equivalent to "ventilation holes becoming blocked holes";

　　正確做法：長孔寬度 5-8mm，搭配防塵網(wǎng)，既通風又防灰，像給窗戶裝紗窗。

　　Correct method: The width of the long hole is 5-8mm, and it is equipped with a dust-proof net, which not only provides ventilation but also prevents dust, like installing a screen window on a window.

　　四、通風孔設計的「反常識操作」

　　4、 Anti common sense operation in ventilation hole design

　　1. 底層橋架孔要「加倍開」

　　1. The bottom bridge holes should be 'double opened'

　　底層電纜被上層「烘烤」，孔密度應比上層多 50%，某汽車廠底層橋架多開 20% 孔，溫度比上層只高 5℃；

　　The bottom cable is' baked 'by the upper layer, and the hole density should be 50% higher than the upper layer. A certain automobile factory has 20% more holes in the bottom bridge, and the temperature is only 5 ℃ higher than the upper layer;

　　類比：就像房間底層比上層熱，空調(diào)出風口要多裝幾個。

　　Analogy: Just like the bottom floor of a room is hotter than the top floor, more air conditioning vents need to be installed.

　　2. 孔位避開電纜接頭

　　2. The hole position should avoid the cable joint

　　接頭是發(fā)熱大戶，孔要開在接頭正上方 5cm 處，某變電站這樣改后，接頭溫度從 110℃降到 75℃；

　　The joint is a major heat source, and the hole should be opened 5cm directly above the joint. After this modification at a certain substation, the temperature of the joint decreased from 110 ℃ to 75 ℃;

　　錯誤示范：孔開在接頭旁邊，相當于「電扇沒對準人」，散熱效果差 60%。

　　Error demonstration: The hole is opened next to the connector, which is equivalent to "the fan is not aimed at the person", and the heat dissipation effect is 60% worse.

　　五、真實案例：這些設計救了命

　　5、 Real case: These designs saved lives

　　某互聯(lián)網(wǎng)機房：橋架通風孔按「橫向 30cm 間距 + 縱向 5cm 高帶」設計，歷經(jīng) 3 年高負荷運行，電纜溫度始終≤60℃；

　　An Internet machine room: the bridge ventilation holes are designed as "horizontal 30cm spacing+vertical 5cm high belt". After three years of high load operation, the cable temperature is always ≤ 60 ℃;

　　某化工廠：將圓孔從 8mm 擴到 15mm，搭配防塵網(wǎng)，橋架火災風險評估從「高危」降到「」；

　　A certain chemical plant: expanded the circular hole from 8mm to 15mm, equipped with dust-proof nets, and reduced the fire risk assessment of the bridge from "high-risk" to "safe";

　　某物流倉庫：底層橋架多開 30% 孔，夏季高溫時電纜溫度比上層僅高 3℃，避免了因散熱差引發(fā)的停工事故。

　　A certain logistics warehouse: 30% more holes are opened in the bottom cable tray, and the cable temperature is only 3 ℃ higher than the upper layer during high temperatures in summer, avoiding shutdown accidents caused by poor heat dissipation.

　　六、避坑指南：3 招驗收通風孔合不合格

　　6、 Guidelines for avoiding pitfalls: 3 methods for checking whether ventilation holes are properly closed or not

　　手測風速：把手貼近通風孔，能明顯感覺到風（風速≥1m/s），某劣質(zhì)橋架幾乎沒風，摸上去像鐵板燒；

　　Hand measured wind speed: Hold your hand close to the ventilation hole and you can clearly feel the wind (wind speed ≥ 1m/s). There is almost no wind on a certain poor quality bridge, and it feels like teppanyaki to the touch;

　　測溫槍掃瞄：運行 2 小時后，橋架表面溫度≤50℃，某問題橋架溫度高達 80℃，摸一下能燙紅手指；

　　Scanning with temperature gun: After running for 2 hours, the surface temperature of the bridge is ≤ 50 ℃. For a certain problem, the temperature of the bridge is as high as 80 ℃. Touching it can burn your fingers red;

　　看積灰情況：合格的通風孔半年積灰厚度≤1mm，某工廠孔太小，3 個月就積了 5mm 灰，相當于「通風孔變堵孔」。

　　Check the dust accumulation situation: The qualified ventilation holes have a dust accumulation thickness of ≤ 1mm within six months. In a certain factory, the holes are too small, and 5mm of dust has accumulated in three months, which is equivalent to "ventilation holes becoming blocked".

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