2020年4月13日星期一

[FS] [AC] 問﹕試述Smoke Extraction / Staircase Pressurization / VAC Control?

答﹕

Smoke Extraction System
Fire compartment 大過 7000m3、Fire Load 大過某個值等就要用,詳見紅皮書。

作用﹕煙向高位走,可以响火燭嗰陣排走啲煙增加逃生機會;仲可以幫助降溫容易救火。

分兩種,一種係Static, 一種係Dynamic
Static Design Criteria
- 每個Zone要500m2內;
- Smoke Barrier, Fixed or automatic activated by smoke detector, 個barrier大細有限制;
- Smoke Discharge Area 要有2% Floor Area, Automatically Operated


Dynamic Design Criteria
- 每個Zone要500m2內,同Static一樣;
- Extraction Rate 大過 8 ACH; Make up air rate 係 Extraction Rate 80%, 保持負壓等啲煙唔洗走去其他地方;
- Make up air 放低位,Extract 放高位;
- Smoke Travel細過30m;
Smoke extraction system 入面如有需要都係用motorised fire and smoke damper;



Fire Damper:
一種叫土炮閘,係要比火燒斷重力跌個閘落嚟,用嚟分開Fire Compartment, 大概只頂到一個鐘;
一種係用電融斷,即係FM200/DG/油缸房嗰種;
仲有種係Fire and smoke damper, 用電訊號嚟啟動個摩打落唔落閘。呢種閘有兩個鐘防火;
[來佬閘呢個講法暫時唔响度提,似乎唔同人有唔同定義,有人話係curtain type, 有人話係fire and smoke damper]

Staircase Pressurization System
Fire compartment 大過 7000m3、Fire Load 大過某個值,Basement面積到某值等就要用,詳見紅皮書。

作用﹕同Smoke Extraction 相反,係谷啲氣入逃生樓梯度做正壓等啲煙唔入唔到去。

Design Criteria
- 加壓到50Pa;
- 開門力道唔過133N;
- 入風位要有Smoke頭,一發覺有煙就熄風扇;
- 四種方法控制裡面風壓,包括Group Floor Open Door; Pressure Relief Vent; Exhaust Fan; Modulating Damper
- BS 5588 Part 4有講啲門漏風等條數係點計;

Ventilation / Air-Conditioning Control VAC
FSD要求,如果Smoke/ Sprinkler 有訊號後,就要關咗棟樓啲MVAC System,有四個方案
Method A - 只關自己嗰個Zone啲MVAC;
Method B - 同Method A一樣,但個Detector係裝响回風度;
Method C - 將成棟樓任何MVAC都關晒;
Method D - 用Smoke Detector去操作範圍250m2裡面既風機熄;

Method A 同 Method B睇落分別不太大,但見得到Method B係自己獨立Smoke頭嚟做Control而唔係用AFA嗰啲頭,加上裝响回風度,咁就會精準啲,冇咁易出False Alarm

(鳴謝﹕紅豆,K)

沒有留言:

發佈留言