Ventilation and Air Conditioning in Workplaces
- Alp Berk
- 24 Jan 2022
- Read in 9 minutes
Update date: 17 Mar 2022
Bilgin CANDEMİR (YTU, Vocational School, Lecturer, Engineering, Engineering, MSC.)

Characteristics of Ambient Air
Atmospheric air; It consists of a mixture of many gases and water vapor, as well as various dirty gases, pollen and smoke. Volumetrically, dry air is approximately 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.03% carbon dioxide, 0.0018% neon, 0.00052% helium, 0.0005% hydrogen, 0.0002% methane, 0-0.0001% sulfur dioxide and 0.0002% total krypton. It is accepted that it consists of xenon and ozone gases. Clean air: Air containing 20.93% oxygen (O2), 79.04% nitrogen (N2) and 0.03-0.04% carbon dioxide (C02). Dirty air is; According to the pollutants it contains and the properties it carries;
Miasma
Toxic Air
Explosive Air
Dusty Air
he leaves.
Dirty Air: Air with less than 20% oxygen content. It has suffocating properties.
Toxic Air: Air that contains gases that disrupt the organism and are therefore very dangerous to life. Gases called poisonous are: Carbon monoxide (CO), sulfurous hydrogen (H2S), nitrogen oxides (NO, N02, etc.), sulfur dioxide (SO2) and radon.
Explosive Air: It is the air containing gas elements of hydrocarbons such as methane (CH4), ethane (C2H6), propane (C3H8) specified with the general formula CnH2n+2, and flammable gases such as hydrogen (H2) carbon monoxide (CO) etc. The most important of these are hydrocarbons (especially methane), and their mixture with air is called 'firing gas' and is a nightmare for miners.
Dusty Air: Air containing stone and/or coal dust. It may have explosive and harmful properties. It causes lung dust disease called 'pneumoconiosis'.
GENERAL PRINCIPLES OF VENTILATION AND AIR CONDITIONING
In its most general form, air conditioning can be expressed as the process of automatically keeping the atmospheric universe (ambient conditions) under control for the purpose of comfort for humans, animals and plants or during the production of an industrial product. In practice, air conditioning is the process of heating, cooling, humidifying or dehumidifying the air, in other words, conditioning the air. Thermal comfort: The main factor in comfort air conditioning applications is people. The absence of any discomfort due to temperature or other weather conditions in a closed environment is called thermal comfort. Factors that need to be controlled to ensure comfort conditions with air conditioning systems can be listed as follows.
1- Air temperature: It is necessary to keep the ambient temperature at the desired level, regardless of the outside temperature, in many ways. A certain ambient temperature is required in order for a production or process to be carried out as desired, as well as for human health, increased working efficiency, and feeling of comfort. Although it varies slightly in winter and summer conditions, people are comfortable in the ambient temperature range of approximately 21-26°C.
2- Relative humidity: The maximum amount of water vapor that can be found in the air at the same temperature is called relative humidity. In other words, it is a measure of how much moisture the air can hold. Relative humidity significantly affects comfort. Because how much heat the human body can release through evaporation is related to the relative humidity of the air.
In some workplaces, the humidity level may be high for technical reasons. If the air temperature is high in environments with high humidity, it becomes very difficult to work. The desired relative humidity range for the workplace environment is approximately 40-60%. If the relative humidity falls below 40%, it will dry out the throat and nose; if it rises above 60%, sweating becomes difficult and body temperature increases.
3- Air speed: It is very important that the air speed remains at a level that does not disturb human comfort. A suitable air flow must be provided in workplaces to ensure comfort and to remove gases and dust that are harmful to health. The most appropriate air flow rate (m/s) and amount (m3/s) will be at a level that will not disturb the employee.
4-Cleaning: Adjusting the temperature and humidity levels of the air alone is not sufficient for both human health and a process. The air must also be purified from foreign substances such as dust, odor and germs. Indoor air generally contains small amounts of outdoor pollutants such as sulfur dioxide or ozone. Indoor pollution sources such as formaldehyde, carbon monoxide and nitrogen oxide are found in higher amounts in indoor air.
5) Noise: The noise that will be generated during air conditioning and delivery to the neighborhood must be at an acceptable level. The weekly noise exposure level determined by adequate measurement in the upper limit of the permissible sound level noise regulation will not exceed the 87 dB limit value. If this noise level is exceeded, various measures must be taken to prevent noise emissions.
İnsan ömrünün % 80 den fazlasının geçirildiği kapalı binaların sahip olması gereken iç hava kalitesi konusunda aranan bazı önemli kriterler: 18 ~ 26 ºC arası kuru termometre sıcaklığı % 40 ~ % 60 arası oransal nem 10 ~ 15 mikron ve üzerindeki toz, tüy, polen..vs den temizlenmesi Ter, yemek, sigara, duman, is... vs kokulardan arındırılması İnsanların rahat ve yeterli solunum yapabileceği kadar oksijen seviyesine sahip olması
In the simplest terms, ventilation can be expressed as replacing used air with new and clean air. However, even if it partially serves the defined purpose; Opening the doors and windows of the living unit, pumping fresh air in with fans, and trying to throw the dirty air out with aspirators should not be perceived as ventilation. Uncontrolled exhausting of dirty air or uncontrolled inhalation of clean air may cause other serious problems. In order to be able to talk about real ventilation, systems where aspirator and fan are used together must be installed. The pressure in the ventilated volume should be controlled, uncontrolled air flows-leakages from inside to outside or from outside to inside should be prevented, and heat losses and gains should not be allowed.
In terms of ventilation and human health and efficiency, the most important element is maintaining the oxygen level inside. To determine this, the amount and positions of oxygen-consuming resources (human-machine-motor-stove, etc.) in the space must be known.
İnsanlar, bünyesel özellikleri yanında Yaptıkları işin cinsine (çalışma, uyuma, oturma vs.) İş yapış şekillerine (oturarak veya ayakta), Yaptıkları işin zorluğuna (ofis işi, berberlik, tornacılık) Yapılan işin temposuna (hızlı, yavaş, orta vs.)gibi parametrelere bağlı olarak farklı miktarlarda oksijen tüketirler. Havalandırma oranının yetersiz olduğu binaları tanımlamak için “Kapalı Bina Sendromu” terimi kullanılmaktadır. ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) standartlarına göre iç ortam havalandırma oranı en az 15 ft3/dak/kişi (≈ 7 L/s/kişi) olarak belirtilmiştir. İç ortamın toplam taze hava değişimi/gereksinimi sayısı saatte 4–6 kez olarak verilmektedir.
It has been observed that if the indoor ventilation rate is less than 10 L/s/person, there is an increase in RLS (Sick Building Syndrome) symptoms. Depending on the features of their applications, air conditioning systems may have all or some of the functions of heating, cooling, humidification, dehumidification, ventilation and filtering.
Natural Ventilation: Ventilation through doors, windows and other openings in buildings without using any air movement (fan) is called natural ventilation. Natural ventilation occurs depending on wind and temperature difference. Among these, the ventilation that occurs due to the effect of wind is called forced convection, and the ventilation that occurs due to temperature difference is called natural convection effective ventilation.
Local Ventilation Industrial local exhaust ventilation systems collect and remove vapors, including particulate matter (dust, smoke, fibers) and gases that create an unsafe, unhealthy and undesirable atmosphere from the environment. Exhaust systems also remove excess heat and humidity while preserving usable materials and keeping the factory clean and tidy. In many manual operations, capturing air pollutants from the source is the only way to meet worker breathing zone limit value requirements. Local ventilation also reduces the need for fresh air required for general ventilation. Which ventilation method should be applied and how the ventilation shape power should be vary greatly depending on the type of work done, factory construction style and dimensions, and expert engineering knowledge is needed in designing the appropriate ventilation system.
The local ventilation system has 5 basic elements.
1. Hood
2.Duct system
3.Dust Collection element
4.Fan
5.Exhaust Chimneys
General Ventilation General ventilation in the industrial environment is done to control hazardous chemical pollutants, odor and heat that may affect the health and safety of workers.
General Ventilation; 1.With natural draft 2.With fans and duct systems 3.With suction only with exhaust fans (fresh air enters the environment automatically)
Fresh air requirement: For safe and effective operation, fresh air must be supplied to many facilities to replace the exhausted air in order to ensure the health and safety of the personnel and to ensure the necessary conditions in the process. Some of the most important measures to be taken into account during fresh air design are as follows; Fresh air should be obtained from the cleanest possible source. A sufficient amount of fresh air should be provided to replace the air discharged through local and general ventilation systems and used to remove pollutants resulting from combustion products. Fresh air systems should be designed according to thermal recovery and energy saving.
Air Conditioning in Workplaces Air conditioning systems contribute to increasing work efficiency by ensuring the health and comfort of employees in factories. In addition, air conditioning systems are effective in obtaining higher quality goods and products in many industries. Examples of this are the tobacco and food industries. In some industries such as textile, confectionery and pharmaceutical industries, air conditioning installation has become a necessity. The first industry to benefit from air conditioning facilities was textile. In cotton manufacturing, all processes of opening, carding, dubbing, roving, spooling, twisting, yarn manufacturing and weaving are carried out at certain humidity and temperature. The relative humidity level suitable for various processes varies between 50% and 95%.
Ventilation is of great importance in mines. The vertical depth in the boron gold mine, one of the deepest mines in the world, is approximately 2400 m. Therefore, the temperature here is around 56.5°C. It is necessary to pay great attention to the ventilation of such mines in order to both cool them and prevent the accumulation of dangerous gases. The use of air conditioning units in the chemical industry, especially in the production of explosive substances and in the pharmaceutical industry, is at least as important as the application areas listed above. Processing of some hygroscopic substances cannot be done in places where humidity is not controlled.
RELEVANT LEGISLATION Articles regarding ventilation included in the occupational health and worker safety regulation, which we used to frequently refer to; (source information) Article 7 In workplaces operating before 17/5/1941, for work that is not harmful to health such as emitting excess heat, steam, gas or harmful dust, this height can be accepted up to 2 meters, provided that the air volume is in accordance with the amount written in Article 8 and adequate ventilation is provided. Article 21 Closed workplaces will be ventilated throughout at least once a day for not less than one hour. In addition, during the working hours of the workers, depending on the nature of the work, the air must be changed frequently to prevent it from becoming harmful to health. However, with this ventilation during work, air currents that will affect the workers will be prevented or the temperature will not be suddenly reduced to very low levels during the winter season.
Chimneys and vents sufficient to attract dust, mist, smoke and bad odors will be installed in places where work is carried out, and other technical measures will be taken in cases where these measures are not sufficient, depending on the nature of the work done. In workplaces where suffocating, poisonous or irritating gases and smoke occur, ventilation will be installed to prevent the life and health of workers from being endangered, and workers will also be given masks and other protective tools and equipment depending on the nature of the work performed. Article 38: In latrines built or to be built in workplaces; 2) In latrines, along with the measures taken against odor such as ventilation chimneys, reservoirs and siphons raised up to the roof, lime cream and similar chemical substances will be used when necessary.
Article 40: Suction and ventilation devices suitable for adequate ventilation will be installed in shower cabins, and odor and dirt will be prevented. Article 41: Changing areas shall be bright, ventilated, adequately heated in cold seasons, and kept clean and well-maintained. General Measures to Be Taken Against Occupational Diseases: Article 59 1) In workplaces where substances that can cause occupational diseases or are registered in the list of occupational diseases are used; Employees will be trained about the properties, harms and prevention methods of these substances. 2) Special posters showing the first symptoms of illness and poisoning due to these substances and the precautions to be taken will be hung in appropriate places in the workplaces. 3) Poisonous and harmful substances used in workplaces will be replaced with less poisonous and harmful substances that do the same job, if technical possibility exists.
4) Work with toxic dust, smoke, gas, vapor, fog or liquids will be carried out in a closed system according to technical possibilities, effective and sufficient ventilation will be provided in such workplaces, and wastes will not be released into the atmosphere and the external environment without being rendered harmless. 5) In workplaces where highly toxic substances are used, their effects will be reduced by isolating these substances and the sections where these substances are located from other places. 6) In workplaces with toxic dust, smoke and steam, the workplace air is humid; Harmful substances will be prevented by keeping floors, walls and counters wet, and when necessary, these works will be carried out together with general and local ventilation. 7) In workplaces where toxic and harmful substances that cause occupational diseases are used, workers will be given appropriate personal protection equipment and will be taught to use them and provided when necessary.
8) In order to be protected from occupational diseases, employment and placement examinations will be carried out regularly, those who are sensitive to the substances used will not be employed in these jobs, and importance will be given to placing people suitable for the job. In addition, health examinations of the workers placed in the job will be carried out at certain intervals and laboratory investigations will be carried out when necessary, depending on the nature of the danger and damage. Special Precautions to be Taken Against Occupational Diseases That May Occur Due to Chemical Effects; Article 62 2) In addition to general ventilation, an effective aspiration system will be installed at the level where mercury works are carried out or sufficiently below, and aspiration hoods will be placed on the work tables. An aqueous system will be established to capture the mercury vapor generated in places where mercury is transferred from the smelting furnaces to the distillation pipe.
Article 67 The following precautions will be taken in the work carried out with manganese and manganese compounds: 2) In places where manganese and its compounds are worked, an appropriate aspiration system will be established along with general ventilation and the work will be in a closed system. Article 68 Preparation of chromium alloys 1) In places where chromium and its compounds are used, an appropriate aspiration system will be established together with general ventilation or the work will be carried out in a closed system. Article 69 Preparation of beryllium alloys 1) In workplaces where beryllium and its compounds are used, an appropriate aspiration system will be established together with general ventilation and the amount of beryllium in the air of this workplace will not exceed (2) milligrams/cubic meter.
Article 71 In studies carried out with aromatic hydrocarbons such as benzene (benzol) and its compounds, 2) In places where benzene and its compounds are worked, an appropriate aspiration system will be installed along with general ventilation and the studies will be in a closed system. Article 72 In studies carried out with aniline and nitro-amine derivatives: 1) In these places, an appropriate aspiration system along with general ventilation will be installed and the studies will be in a closed system.
Article 73 In works carried out with halogenated hydrocarbons: 1) Workplaces where halogenated hydrocarbons are worked will be separated from other parts and in these places, an appropriate aspiration system will be established along with general ventilation and the works will be in a closed system. Article 74: 2) In places where carbon sulphide is used, an appropriate aspiration system will be installed along with general ventilation, the work will be in a closed system and the amount of carbon sulfur in the workplace air will not exceed 20 P.P.M. or 60 milligrams per cubic meter. Article 75 In studies carried out with sulfur hydrogen; 1) In places where sulfur hydrogen is used, an appropriate aspiration system will be installed along with general ventilation.
Special Precautions to be Taken Against Occupational Diseases That May Occur with Dust; Article 76 1) In dusty workplaces, together with general ventilation, water curtains, vacuum and remote control systems will be installed to prevent the spread of dust into the ambient air with an appropriate aspiration system. Works that generate dust will be carried out in a closed system or isolated from others, depending on technical possibilities. The amount of dust in the workplace air will not exceed the specified amount. Safety Precautions to be Taken in Boilers, Pressure Vessels and Compressors; Article 213 Boiler rooms will be constantly ventilated. In cases where natural ventilation is not sufficient, appropriate aspiration installation will be installed.
Safety Precautions to be Taken in Boilers, Pressure Vessels and Compressors; Article 213 Boiler rooms will be constantly ventilated. In cases where natural ventilation is not sufficient, appropriate aspiration installation will be installed. Safety Precautions to be Taken in Lifting, Transporting, Stacking and Storage of the Material; Article 496 Silos where flammable dry materials are stored in cast form will be made of fire-resistant materials and they will have appropriate ventilation equipment.
Safety precautions to be taken during maintenance and repair works; After the steam or stream is introduced, any debris that may collect at the bottom will be cleaned appropriately and the tank will be ventilated by air pressure or suction for at least 2 hours. At the end of the ventilation, the inside of the warehouse will be checked by the relevant authorities, and if it is understood that the warehouse is not cleaned properly as a result of the checks and analyses, cleaning and ventilation with water or steam will be repeated.
REFERENCES 'COOLING TECHNIQUES AND APPLICATIONS' textbook, Nurettin Yamankaradeniz Vipaş 2008 'AIR CONDITIONING PRINCIPLES' textbook, Nurettin Yamankaradeniz Vipaş 2008 Regulation on Health and Safety Measures to be Taken in Workplace Buildings and Attachments Official Gazette Dated 17 July 2013, Issue: 28710 http://www.mevzuat.gov.tr
