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影响通风柜气流控制效果的因素
发表时间:2016-12-23     阅读次数:     字体: С

通常情况下,会影响通风柜气流控制目标的因素包括:通风柜结构、面风速、扰流、响应时间、最小排风量。而为了应对管理目标以及可能发生的意外情况,各国规范通常对就地监视、紧急操作等方面也有较为具体的规范要求。
通风柜结构
要求其通风柜内部结构设计合理,通风柜任意两点处面风速偏差小于等于15%,整体结构阻力小于70Pa。且按照EN或ASHRAE相关标准,通风柜在出厂前需经过一系列严格测试。
通风柜面风速
气流经过通风柜操作面进入通风柜的速度,称为通风柜面风速。
面风速是反应通风柜气流抑制效果的重要参数之一,各国均有明确标准要求。通常情况下,要求通风柜前有人操作时,由于其身体在通风柜前会形成一个气流真空,因此,面风速要求控制在0.5m/s,当通风柜前无操作人员时,则可适度降低面风速至0.3m/s。德国DIN标准,由于其对于通风柜结构要求有别于其他国家标准,因此其面风速标准要求低于其他各国标准。

Under normal circumstances, factors that affect the fume hood airflow control objectives include: fume hood structure, surface wind speed, turbulence, response time, the minimum air volume. And in response to the management goal and the possibility of unexpected circumstances, the specification is usually for on-site monitoring, emergency operation, etc, also have more specific specification requirements.

Fume hood structure

Ask its ventilation cabinet structure design is reasonable, any two points of the fume hood surface wind speed deviation less than or equal to 15%, the overall structure resistance less than 70 pa. And in accordance with the relevant EN or ASHRAE standard fume hood need through a series of strict test before they go out.

Ventilation counter wind speed

Into the fume hood airflow through the operation of the fume hood face velocity, called ventilation counter wind speed.

The surface wind speed is reaction hood inhibition effect is one of the important parameters, many countries have clear standards requirements. Normally, asked someone before fume hood operation, due to its body in front of the fume hood will form a vacuum airflow, therefore, surface wind speed requirements control in 0.5 m/s, when no operator before the fume hood, can be appropriate to reduce the surface wind speed 0.3 m/s. German DIN standard, due to its requirement for the fume hood structure is different from other national standards, so the surface wind speed standard requirement is lower than the rest of the world.

美国职业卫生与安全管理局(OSHA) - 0.3 至 0.5 m/s
美国工业卫生委员会(ACGIH) - 0.3 至 0.5 m/s
美国国家标准化组织(ANSI) - 0.4 至 0.6 m/s
Prudent Practices – 0.3 to 0.5 m/s
美国流体动力学会(NFPA)-“通风柜应严格限制可能发生的危险,保障人员安全”
德国国家标准协会(DIN) - 0.3 m/s
中国建筑工业行业标准(JG/T) - 0.5 m/s

The occupational health and safety administration (OSHA) - 0.3 to 0.5 m/s

The American industrial hygiene committee (ACGIH) - 0.3 to 0.5 m/s

The national organization for standardization (ANSI) - 0.4 to 0.6 m/s

Prudent Practices - 0.3 to 0.5 m/s

The national institute of fluid power protection agency (NFPA) - "fume hood should strictly limit the possibility of danger, to ensure the safety of personnel"

Association of German national standard (DIN) to 0.3 m/s

China building industry standards (JG/T) to 0.5 m/s

 
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