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Power division of ventilation system

Nov 14, 2018

Divided by the power of the ventilation system:

 

1. Natural ventilation is the ventilation method caused by the wind pressure caused by outdoor wind and the hot pressure generated by the indoor and outdoor temperature difference to make the air flow;

2, mechanical ventilation is the way to rely on the power of the fan to make indoor and outdoor air flow.

 

Divided by ventilation system:

 

1. Full ventilation is to ventilate the whole room. The fresh air sent into the room is used to dilute the concentration of harmful gases in the room below the allowable range of sanitary standards. At the same time, the indoor polluted air is discharged directly or after purification. Go outside in the atmosphere. The full ventilation of the laboratory generally uses the top tuyere to exhaust.

2, the local ventilation of the experimental bench is to take local airflow, so that local sites are not polluted by harmful substances, resulting in a good working environment; local ventilation generally includes: fume hood exhaust, universal exhaust hood exhaust, desktop hood lining Wind and so on.

Third, the laboratory is generally applicable: when designing the ventilation system, first consider local ventilation, and if it does not meet the requirements, then use full ventilation. Also consider the combination of architectural design and natural ventilation. The laboratory generally uses a combination of local ventilation and full ventilation. Among them, local ventilation can ensure the reasonable and effective removal of harmful substances at the experimental site; comprehensive ventilation is used to eliminate the harmful substances scattered in the laboratory and to ensure the laboratory's sanitary environment.

FUME HOOD 9.19

First, the introduction of the fume hood


  Fume hoods are an essential part of laboratory furniture. It plays the role of ventilation and ventilation in the laboratory. The structure of the fume hood is of the upper and lower type, and has a vent hole at the top to install a fan. There are baffles in the upper cabinet, the circuit controls the touch switch, the power socket, etc. The see-through window is made of tempered glass, which can be moved left and right or up and down. For human operation. The lower cabinet adopts the experimental side table style with a countertop on top and a cabinet on the bottom. Small cups and faucets can be installed on the countertop. The material of the fume hood is various, all steel, steel wood, all wood, aluminum wood, plastic steel, PVC structure, etc. The table top is directly in contact with the operator, from solid core physics and chemistry board, stainless steel plate, PVC, ceramic And other materials.

 

Second, the choice of fume hood


  The fume hood is not a separate piece of equipment and changes in the external environment can affect the performance of the fume hood. At the same time, the fume hood and its control system can also affect the environment around him, when you choose the fume hood:

First of all: the factors of the entire system must be taken into account. According to the material: all steel fume hood, steel wood fume hood, all wood fume hood, glass reinforced fume hood.

Second: You need to determine which type of fume hood you need. When choosing, you can usually measure by:

 

1. Upper cabinet part:


There are three styles: standard, low table, floor type.

Whether the surface wind speed of the fume hood meets the requirements of the international standard for safe wind speed: 0.5m / s (standard: only the surface wind speed of 0.5m / s can effectively capture the harmful gases in the cabinet).

The opening height of the fume hood is suitable for your operating space.

Ventilation control system: constant air volume, variable air volume or adaptive control system.

Lining material: PP, fiberglass or polyethylene resin.

Whether the material of the door is adjusted with safety glued glass is designed to conform to the human body mechanics, so that the operator can pull freely. 2. Countertop part:

Whether the countertop uses a safe dish design makes it easy for users to clean the countertop and prevent leakage of toxic liquids.

Whether the material of the countertop meets the requirements of your experiment and resists the corresponding erosion and high temperature.

Is there a cup slot or sink installed and the location is reasonable?

Whether the design of the air outlet is reasonable.

 

3. Base cabinet part:

 

Whether the material is strong and durable, whether it is fireproof material, whether it can resist the erosion of the laboratory acid and alkali environment.

Whether the power supply is reasonable and safe.

Is it easy to repair water, electricity and gas systems?

Whether the base cabinet needs a pumping design so that you can place volatile drugs.

Once you have basically selected the model, style and size of the fume hood, you can determine what you need based on the following conditions. 4. Accessories:

Water source: distilled water, pure water or reverse osmosis water.

Source of gas: nitrogen, oxygen or air.

The choice of electrical system should be considered: model, voltage, riot, durability and so on.

For aesthetic reasons, it is necessary to seal the board.

 

 

Third, the main function of the fume hood

 

  The main function of the fume hood is the exhaust function. In the chemical laboratory, various harmful gases, odors, moisture and flammable, explosive and corrosive substances are generated during the experimental operation. In order to protect the safety of the user, Prevent the spread of pollutants in the laboratory to the laboratory. Use a fume hood near the source of pollution. In the past, the number of fume hoods used was small, and it was only used in experiments with particularly harmful and dangerous gases and large amounts of heat. The fume hood is only responsible for the auxiliary functions of the test bench. The purpose of using the fume hood is to remove the harmful gases generated in the experiment and protect the health of the experimenter, that is to say, to have a high degree of safety and superior operability.

(1) Release function: The mechanism for absorbing the harmful gas generated inside the fume hood to absorb the gas outside the cabinet should be diluted to exclude the outdoor unit.

(2) Non-backflow function: It should have the function of the airflow generated by the exhaust fan inside the fume hood to prevent harmful gas from flowing into the room from the inside of the fume hood. In order to ensure the realization of this function, it is a good method to connect a fume hood with a single pipe with a single ventilator. It cannot be connected by a single pipe. It is also limited to the same room in the same floor. The ventilator can be installed as much as possible. At the end of the pipe (or at the top of the layer).

(3) Isolation function: The inside of the fume hood should be separated by a non-sliding glass window.

(4) Supplementary function: There shall be a passage or alternative means for drawing in air from outside the fume hood when harmful gases are exhausted.