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Laboratory Fume Hood Lab Bench Ventilation System Design

Aug 21, 2017

Laboratory ventilation system engineering is the use of ventilation dilution or ventilation exclusion to control the spread of air pollution and harm, is to achieve indoor and outdoor air quality assurance of a building environment control technology. Ventilation system is to achieve the ventilation of this function, including the inlet, exhaust, air duct, fan, cooling and heating, filters, control systems and other ancillary equipment, including a complete set of devices.

Laboratory ventilation engineering general use of mechanical ventilation, mainly by means of ventilation power equipment and fully ventilated, local ventilation equipment, such as fume hood, atomic absorption hood, universal exhaust hood, etc. exhaust. Fume hood fume hoods as an important safety device in the laboratory, it can provide an effective local ventilation.


(1) the use of fume hood environment: for flammable and explosive and volatile toxic and harmful gas experimental operation, the performance of unknown items detection, qualitative and quantitative experimental operation.


(2) fume hood structure style: three sections of the desktop (OTC, operating table, under the cabinet); bench top fume hood / floor-type fume hood.


(3) Fume hood type: steel and wood fume hood, all steel fume hood, FRP fume hood, PP fume hood


Ventilation frequency conversion system to make the individual equipment exhaust volume to meet the design requirements, and to ensure that each ventilation equipment in a separate operation does not affect the normal operation of other ventilation equipment, the use of ventilation and frequency conversion system.


(1) the principle of frequency conversion system is when some of the fume hood is not used or the angle of the electronic fan of the fume hood changes, the ventilation head of the ventilation volume changes, while the ventilation head of the differential pressure will change, then the differential pressure sensor Duct pressure changes, through the signal line transmission to the inverter, through the inverter automatically adjust to control the fan motor speed, so as to achieve the purpose of controlling the exhaust volume.


(2) Frequency conversion mode: constant air volume variable frequency / variable air volume frequency conversion


① constant air volume frequency control mode:


The system is designed according to the air volume of all the ventilation equipment. The air volume of each ventilation equipment is constant, and the frequency of the fan operation is controlled by the angle controlled by the electronic damper installed at the end of the tuyere and the variable frequency of the pipe , To meet the use of ventilation ventilation system, when the switch is closed to increase the amount of air flow through the switch off to reduce the air flow.


Advantages: energy saving. By saving the fume hood and the room to a low air flow, significant energy savings can be achieved. The use of fast, stable adjustment method to achieve high-quality flow control. Compared with the variable air volume control system, the control system equipment is low cost.


Disadvantages: High-low (or maximum-minimum) switching between two predetermined wind flow values. Unknown adjustment door open position level, surface wind speed may be high or low, may reduce the safety.


② variable air volume frequency control mode:


The wind speed of the fume hood is constant and the opening degree of the control valve is maintained, and the frequency of the fan is controlled to meet the required wind speed of the fume hood setting surface to reach the control effect of the wind speed of the ventilation cabinet The While ensuring the dust collection capacity of the fume hood and significant energy saving.


Advantages: Adjust the door when the energy saving significantly; adjust the door position changes to maintain the correct surface wind speed, increased security; inherent alarm and monitoring function is a typical component of the variable air volume system, while increasing security. As the variable air volume control system is easy to adapt to system changes, laboratory flexibility will increase. As the air flow decreases, the sound level will be reduced.


Disadvantages: If the adjustment door remains open, there will be high wind flow and high operating costs. The cost of the control system will result in high investment costs. Because the general adjustment of the door position to determine the air volume, the incorrect regulation of door management will affect the investment recovery, sound effects, uneven situation. Different VAV system performance is different, different systems, control speed, regulation ratio, stability and maintenance needs are significantly different.


The laboratory in the course of daily operation will produce the corresponding exhaust gas, such as untreated direct discharge into the atmosphere is bound to cause pollution to the surrounding environment, and will cause damage to the human body, for the exhaust gas contained in the inorganic exhaust and organic waste gas, according to the exhaust The different types of different exhaust gas to deal with the program




Activated Carbon Adsorber Working Principle


Chemical smoke and harmful gases through the fan into the activated carbon adsorber, activated carbon and smoke molecules oxidation reaction and adsorption reaction, and was hydrolyzed into carbon dioxide and water, thereby reducing environmental pollution.


Water spray purification tower working principle


The fan is driven by chemical acid mist through the water spray device, encountered in the spray into the fine mist and the liquid, the exhaust gas is absorbed into the surface of the fine droplets and discharged into the collection tank, clean air into the step filter after the discharge to the Atmosphere, the liquid through the pump from the collection tank to the upper part of the nozzle spray, and the exhaust gas neutralization reaction after the discharge into the collection tank, waste treatment after discharge to the outside or recycling.