BASIC PRINCIPLES IN OCCUPATIONAL HYGIENE Day 2 2

BASIC PRINCIPLES IN OCCUPATIONAL HYGIENE 职业卫生基本原则 Day 2 第 2天

10 – VENTILATION 10 -通风

GENERAL VENTILATION 全面通风

Local exhaust ventilation (LEV) systems 局部排气通风（LEV） 系统 Source: Adrian Hirst 资料来源：Adrian Hirst

General Features of an LEV System 常见LEV系统组成 风扇 排气口 管道 空气净化器 外罩 Source: Adrian Hirst 资料来源：Adrian Hirst

Inlets/Hoods 进气口 /外罩

The three basic types of LEV hood 三种基本型LEV外罩 Enclosing (Contain and separate) 封闭外罩 （容纳式，隔离式） Receiving (Receive, contain & empty) 受体罩（接受式，包含式，和清空） Capturing (Capture) 采集罩（采集式） Source: HSE 信息来源： HSE

Enclosures 封闭罩 Full 全面型 LEV hood classification expanded LEV外罩分类（扩展型） 进气 Partial, small 局部型、小型 Partial, large 局部型，大型 Room 室内型 出气 Receiving 受体罩 Hot 热流 Capturing 采集罩 Source: HSE 资料来源：HSE 过滤器

LEV system design, the most critical element is the hood LEV系统设计——外罩是最关键要素 Main reasons why systems fail to protect: 系统无法提供保护的主要原因： • Incorrect type of hood is chosen (and could never provide sufficient protection) • 所选外罩类型不当（根本不能提供足够的保护） • The airborne contaminant isn’t contained or captured. • 不能容纳或采集气载污染物 • LEV hood design doesn’t match the process and source(s) • LEV外罩与 艺和污染源不符 • Insufficient airflow (various reasons). • 气流不足（各种原因）。 Source: HSE 资料来源：HSE

Capturing Hoods 采集罩 Process takes place outside hood, hood-induced airflow has to “capture” contaminant-laden air 艺在外罩外围实施，外罩促发式气流应采集污染空气 Side-draught captor hood 侧向气流式采集罩 (adapted from Hemeon’s Plant and Process Ventilation) （取自Hemeon的厂房和 艺通风） Source: HSE 资料来源：HSE

Capturing Hoods 采集罩 The process, source and contaminant cloud are outside the hood 序操作、污染源和污染 物云均在外罩外围。 Hood has to generate sufficient airflow at and around the source to ‘capture’ and draw in the contaminant-laden air 外罩需要在污染源附近和周围产生足够的气流， 以“采集”并吸入污染气体 (adapted from Hemeon’s Plant and Process Ventilation) （取自Hemeon的厂房和 艺通风） Source: HSE 资料来源：HSE

Capturing Hoods – interrelated properties 采集罩——相关联特性 • Capture velocity, distance and zone (new(ish)) • 采集速度、距离和区域（全新） • Process induced air movement and draughts • 空气流动和通风方法 • Airflow, velocity contours and flanges • 气流、等流速线和凸缘 • Capture ‘bubbles’ (new) • 采集“气孔 ”（新增） • Capture curve (new) • 采集曲线（新增） • Capture zone and Working Zone (new). • 采集区和 作区（新增） Source: HSE 资料来源：HSE

Capture of vapour-laden air: evaporation 采集蒸汽式空气——蒸发 Air velocity required at this point to “capture” vapour-laden air ~0. 5 metres per second (m/s) 采集蒸汽式空气的空气 流速~0. 5米每秒（米/ 秒）。 Source: HSE 资料来源

Capture of vapour-laden air: drum filling 蒸汽空气采集：桶装型 Air velocity required at this point to “capture” vapour-laden air ~2. 5 metres per second (m/s) 采集蒸汽式空气的空气 流速~2. 5米每秒（米/秒 ）。 Source: HSE 资料来源：HSE

Receptor Hoods 受体罩 Source: HSE 资料来源：HSE

Enclosing Hood 封闭罩 Source: HSE 资料来源：HSE

Types of LEV used for various processes 各 序用LEV类型 Industrial process 序 Nature of hazardous substance 危险物质性质 Types of LEV Welding fume: fine particulate with some natural buoyancy 焊接烟尘：有天然浮力的细颗粒 Capture hood positioned close to the welding activity; or Tip extraction fitted to the end of the welding gun 靠近焊接操作的采集罩；或安装在焊枪末端的焊料提取 Mist and solvent vapours released in controlled direction with velocity 排放方向和速度受控的漆雾和溶剂 Walk in paint spray booth 喷漆房内走动 Down flow booth 降流外罩 Metal and polishing dust released in controlled direction with high velocity 排放方向和速度受控的金属和抛光粉尘 Receptor hood and enclosure around the polishing wheel 抛光轮周围的受体外罩和封闭罩 Steel shot and metal dust from components released at high velocity in variable direction 以高速变向释放的组件中的钢丸和金属 粉尘 Fully enclosed glove box type cabinet with airflow managed to compensate for compressed air input and shot recycling system 全封闭的手套式操作箱（气流受控，可对进气和钢丸循 环系统进行补偿） Hand held orbital Sander 手持轨道 、磨沙机 Wood dust released in variable directions 变向释放的木屑 Extraction integrated into the sander disc 从砂光机中的提取 Paint curing Ovens 涂料固化 烘炉、 Hot air and curing vapours with strong thermal buoyancy 热浮力强的热空气和固化蒸气 Extract/vent from top of oven combined with a receptor hood over the doorway 从在门口配置有受体外罩的烘炉顶层的提取/排出 Laboratory analysis 实验室分析 Acid and solvent vapours released with low velocity and little direction 低速和小角度排放的酸与溶剂蒸气 Partial enclosure and extraction within a fume cupboard 部分封闭，从通风橱内提取 焊接 Paint spraying Polishing 喷漆 抛光 Shot blasting 抛丸 类型 Source: HSE 资料来源：HSE

Capture Zone / Capture Bubble 采集区/采集气孔

Movable capturing hood – capture ‘bubble’ 移动式采集外罩——采集气孔 Capture bubble 采集气孔 Source: HSE 资料来源：HSE

Capture ‘bubble’ varies in size 采集气孔大小不同 Source: HSE 资料来源：HSE

Capturing hood capture ‘bubble’ 采集罩的采集气孔 Source: HSE 资料来源：HSE

Capture zone must encompass working zone 采集区应在 作区周围 Capture zone 采集区 e on z g in k r Wo 区 作 Source: HSE 资料来源：HSE

Ductwork 管道 Ductwork carries the extracted air and the contaminant from the inlet to the air cleaning device. 管道系统将从进气口提取的空气和污染物排放到空气净化装置中。 – Velocity Important – 速度是关键 – Should be sufficiently strong – 管道应有足够的强度 – Well supported and capable of withstanding normal wear and tear – 支撑良好、能够承受正常的磨损 – The number of changes of directions should be kept to a minimum – 应确保变向次数最少 – Should be made smoothly – 应确保变向顺畅 – Access to ducting may be required. – 应配置管道检修口

Duct Velocity 管道流速 Type of contaminant 污染物类型 Duct velocity (m sec-1) 管内流速(m sec-1) Gases (non‑condensing) 气体（非冷凝） No minimum limit 无最低限制 Vapours, smoke, fume 蒸气、烟雾、烟气 10 Light/medium density dust (e. g. sawdust, plastic dust) 轻/中密度粉尘（如木屑，塑料粉尘） 15 Average industrial dusts (e. g. grinding dust, wood shavings, asbestos, silica) 业粉尘平均速度（例如磨削尘、刨花、石棉，硅石） 20 Heavy dusts, (e. g. lead, metal turnings and dusts which are damp or that tend to agglomerate) 重金属粉尘（如铅、金属屑和潮湿易结块的粉尘） 25 Source: HSE 资料来源：HSE

Air Cleaners – Filters 空气滤清器——过滤器 Source: Adrian Hirst 资料来源：Adrian Hirst

Air Cleaners – Cyclones 空气滤清器——湿式旋风除尘器 Source: Adrian Hirst 资料来源：Adrian Hirst

Air Cleaners - Wet Cyclone & Induct Spray 空气滤清器——湿式旋风除尘器和喷雾引射器 Source: Adrian Hirst 资料来源：Adrian Hirst

Maintenance, Examination and Testing of Ventilation Systems 通风系统的维护、检查和测试 In order to function correctly it must be in good working order. 为了确保正常 作，LEV必须保持良好的运转状态。 – Legal requirements – 法律要求 – Regular Maintenance – 定期维护 – Thorough Examination and Testing. – 全方位检查和测试