Local ventilation systems are systems that mechanically absorb dust and dust at the source, with or without treatment, before being discharged to the outside environment. To better understand the local ventilation system, please read the detailed article

What is local ventilation system?

Different from the natural ventilation  system, the local ventilation system  includes dust collectors at the dust emission sources (crushers, grinders, mixers, sieves, buckets, on conveyor terminals), pipelines, etc. corrugated iron guide, dust filter equipment and exhaust fan. This is a type of forced ventilation system used to ventilate a small area.

Using Local Ventilation System helps to ensure worker’s health. There are two commonly used types of local ventilation systems: local dust extraction systems and local toxic gas extraction systems.

Principles for effective local ventilation

The following principles should be ensured for good pollutant capture with high efficiency:

– Capture as close to the source of pollutant discharge as possible.

– The air intake is as close to the pollutant discharge source as possible.

– The speed of collecting dust or toxic gas must be large enough to absorb all emitted pollutants.

– Pollutants catching mouths must not interfere with technological activities

– Contaminated air entering the suction cup must not pass through the respiratory zone of the operator

Classification of local ventilation duct systems

With the superiority and convenience, the ventilation duct system has been divided into many types depending on the purpose and usage situation.

1. Follow the direction of wind movement

– Blower type ventilation:  Blows clean air into the interior space through openings thanks to the differential pressure. The advantage of this method is that it can supply wind and clean air into the room, where there are many people or excess heat, but the disadvantage of this method is that the pressure in the room is positive, so the wind spreads in all directions. even unwanted places.

– Suction ventilation:  Exhaust contaminated air from the room and outside air enters the room through openings or fresh air intakes thanks to the difference in pressure. This method has the advantage of being able to directly absorb the polluted air in the space, preventing it from spreading around. However, the disadvantage of this method is that the circulation in the room is very low, almost non-existent. On the other hand, the air entering the room is free, uncontrolled.

– Combined ventilation:  Combining both blowing clean air into the space and sucking out the stuffy air, this is an effective method. Ventilation combines exhaust and blow, including exhaust fan and blower system. This method is a combination of the advantages of the above two methods. However, it requires higher investment costs.

2. According to the method of organization

– General ventilation:  Overall ventilation for the entire room or building

– Local ventilation:  Ventilate a designated area or rooms containing a lot of hazardous waste.

3. According to the dynamics of creating ventilation

– Natural ventilation:  Is the exchange of air indoors and outdoors thanks to the difference in pressure. Usually the head is created due to the temperature difference between the outside and inside.

– Forced ventilation:  The ventilation process is done by external force ie using a fan.

4. According to the purpose

– Normal ventilation:  The purpose of the ventilation duct system is to remove harmful substances, excess heat, excess moisture and provide fresh clean air for human living space.

– Ventilation incidents:  Many buildings are equipped with ventilation duct systems to overcome problems that occur.
Prevention of chemical spills: When there are problems, the ventilation system works and releases toxic gases to predetermined places or to the outside.

– In case of fire:  To prevent fire from entering the stairs and exit doors, the air intake system works and creates positive pressure on these sections for people to escape easily.

How to install a local ducting system

Ventilation duct systems are usually divided into two main types: natural ventilation systems and mechanical ventilation systems.

1. With natural ventilation

– Users can build and design themselves through devices mounted on the roof or through doorways such as fans, openings.

2. For mechanical ventilation system

– This is a specialized device that requires installation by skilled refrigeration mechanics. This mechanical ventilation system will actively suck in air from the outside and push the old air out into the environment.

Depending on the conditions of each person as well as the conditions of the factory ventilation duct installation, one can install the system on the ceiling, roof or basement ventilation system, manufacturing plants. , oil refinery…

Instructions for checking local ventilation systems

Smoke testing is a simple method to know the direction, strength and weakness of the air flow (clean air enters the work area and dirty air is discharged). There are different types of smoke tests. There is a pattern that produces a lot of smoke that is harmful to your health. Some other styles produce less smoke and are safer, for example a burning match. Smoke testing can be done with smoke bottles, smoke pens, powders and matches. (In case there is a fire alarm device installed in the pipeline, the smoke test method should not be used).

If you don’t have any of the above, burn things to produce enough smoke to test. Do not use fire near chemicals, dust and flammable and explosive manufacturing processes. Another way to check for moving air is to stick thin, light strips of paper to a stick but do not bring it too close to the suction mouth as the paper can get caught in it. Here’s how to check the intake ventilation system.

• Use sticks, cigarettes, cigars, bunches of leaves or paper, which burn slowly and produce a lot of smoke. If you are working with chemicals or processes that are flammable or explosive, do not use anything flammable, but instead use a small-mouthed bottle filled with baby powder because it easy to fly like smoke when shaken gently.
• Turn on the vacuum cleaner closest to where you work.
• Stand or sit where you work.
• Start creating smoke and see where the smoke goes? how to move? What changes when someone passes or blocks the air intake?
• If the smoke goes directly towards the intake manifold and all the smoke is sucked in, the hood is working efficiently.
• If the smoke moves towards your face, to another work area, or to another direction, something is definitely wrong. Is there not enough air for the smoke to enter the intake manifold? Does the movement around you affect the direction of the smoke or perhaps the hood isn’t powerful enough? Ask other workers to do the same as you.
• If all the smoke doesn’t get into the exhaust system, you and your coworkers can pressure your employer to find a technician to fix the problem.

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