In general, ventilation is the mean of removing contaminated indoor air and replacing it with fresh air. Industrial ventilation can be found in almost every workplace and its goal is to push the air outside without recirculating it to the inside. A ventilation system is considered as one of the major facilities that we need to install in the factory or warehouse in order to maintain the safety of the working environment and reduce the chance that workers are exposed to contaminated air. Especially for those places that use or produce volatile chemicals or toxic, a proper ventilation system installed at the place can improve the overall indoor air quality, reduce the risk of explosion and fire, and create a pleasant working environment. In addition, the air brings into the workplace at a certain speed also can create the required air pressure to maintain the temperature, humidity and ensure a cost-saving for cooling and heating. Basic ventilation can be achieved by just opening windows, allow the hot and harmful air to flow out and clean air to flow in naturally. With the use of mechanical methods, a fan or blower is much quicker and more efficient at moving the air and reaching a better ventilation result.
There are two main types of mechanical ventilation methods which are dilution ventilation and local exhaust ventilation.
Dilution ventilation is used to dilute the contaminated air with fresh air using a mechanical device such as an exhaust fan or a large commercial fan. The exhaust fan is usually installed in the roof or wall of the factory or warehouse to direct the air away from the workers. It works by expelling out the contaminated air from the environment and then minimizing the concentration of pollutants in specific areas. Dilution ventilation is only suitable to be installed in certain conditions and environments, such as where the contaminants are gases or vapors, the air pollution or toxic level is low to moderate, and the emissions are uniform and widely distributed. It is also recommended to be used for some moderate climatic environments.
Dilution ventilation is required less installation cost with little maintenance and equipment needed. It can also be used for mobile or scatter sources of pollution. However, it can not be used for the hazardous environment that has high concentrations of dust, gases, fumes, vapors, or toxic chemicals. It is also not recommended to use dilution ventilation in the workplace that has irregular emissions of contaminants as it may not circulate the air effectively.
Local Exhaust Ventilation
Local exhaust ventilation (LEV) is the most efficient ventilation system to prevent contaminants and ensure a high level of safety in the working environment. Its purpose is to stop contaminants before spreading. Unlike the dilution ventilation which relies on the fan to distribute the air, the exhaust ventilation acts like a vacuum as it captures the contaminants at the source and then expels them outside. The working principle of exhaust ventilation is to move the air from high-pressure areas to low-pressure areas. The fan generates the differences in pressure that draws the air through the ventilation system. We must always consult the professional or ventilation engineer to make sure the exhaust ventilation system can generate sufficient airflow to capture the airborne contaminants.
Exhaust ventilation is very suitable to be used in high air contamination concentrations to remove high levels of toxic chemicals, dust, fumes from the industrial process and equipment. It can be used for the factory in severe climate locations and has inconsistent emissions over time. In comparison with dilution ventilation, exhaust ventilation use less energy than dilution ventilation system and is also good at reducing the energy heating and cooling costs. But it requires a higher design and installation cost at the beginning. And, periodic maintenance is required for exhaust ventilation to keep the system well functional and works effectively.
Several parts are included in the exhaust ventilation system:
It is used to capture the air pollutants at the source. It should be located as close as possible to the source of the contaminants. Workers should not stand in between the hood and the source of contaminated air to ensure effective working of the ventilation.
The contaminated air travels within the ducting system to move from one area to another. A regular inspection of the ducting system is necessary to avoid any buildup of dust inside of it.
3. Air filter system/Air Cleaner
It is used to clean and filter the air as it moves. We must select the air cleaner with the filter that is suitable for the contaminant to be handled. And it should be easy to clean and replace without the risk of exposure.
It moves the air from the hood, to ducting, and then exhaust stack to blow it outside. Consult the engineer on the right type and size of fan for the ventilation system to ensure it can move the air effectively.
5. Exhaust stack
This is where the contaminated are removed. It should be located at the outside wall of the building or through the roof. We have to make sure that the system is releasing the correct volume of the air and without any leakages.
There are some limitations in most industrial ventilation systems. The ventilation system requires periodic maintenance and cleaning as the contaminant will build up over time, especially in the filter. Regular testing and modification are required to be done by qualified persons to identify the system problem and implement a corrective modification to ensure the system can continue to work effectively. We should also avoid making any unauthorized changes to the ducting system as it may affect the overall airflow and result in rapid plugging of the system.
A poor design and installation of the ventilation system can reduce its capacity and functionality in capturing the contaminated air and result in a risky working environment. We must understand the ventilation requirements such as the type and volume of contaminant when choosing the right type and design of the industrial ventilation system. Qualified ventilation professionals or engineers will design and install the ventilation system according to our requirements and make sure the working environment is meeting the industrial safety & health standards.
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