Ventilation and Air Conditioning in Workplaces-2

Bilgin CANDEMİR (YTU, Vocational School, Lecturer, Engineering, Engineering, MSC.)

GENERAL VENTILATION AND AIR CONDITIONING

Ambient Air Quality; It is necessary to ensure the necessary air quality in the workplace environment for the health and safety of employees.

Factors Affecting Ambient Air Quality are as follows; Temperature of the air, Humidity of the air, Air flow speed, Pollutants in the air. The basic condition for the health of employees is provided by keeping the body temperature at a normal level and removing pollutants from the environment.

Appropriate and sufficient ventilation is an important precaution to be taken in the environment to ensure this balance. Considered together with its ventilation, heating, cooling and humidification features, it is an important part of workplace air conditioning. In this respect, ventilation ensures that the working environment is satisfactory for both production and product and the thermal comfort of employees.

Ventilation; It is a measure to protect employees from the negative effects caused by heat and factors that pollute the ambient air by reducing the temperature of the working environment and reducing the level of air pollutants in the working environment that employees have to breathe.

Ventilation; They are examined in two groups: general ventilation and local ventilation. The sources that cause the working environment temperature to increase are as follows: Work done in the workplace, external factors, employees, sources of pollution in the working environment, work done in the workplace, external factors, characteristics of the work, etc.

Factors that pollute the working environment air; It consists of chemical, physical and biological factors. ventilation; It is the process of simultaneously removing the air from the working environment and replacing it with fresh air. However, in some cases, providing adequate ventilation is done by mobilizing the ambient air.

In environments where industrial work is carried out where flammable gases are used or emitted, this type of ventilation is necessary to prevent glare. Ventilation is a very useful tool to control heating and pollution.

Because the high heat (a significant part) of the pollution occurring in the workplace working environment is transmitted to the employees through the air. The heat in the ambient air is stored in the gases that make up the air. The gases, dust and other polluting factors that form the air pollution in the working environment are mixed with the air. For these reasons; The processes of distributing heat and pollution in the ambient air and removing them from the environment are more or less the same.

Dissipation of heat and pollution in the ambient air; It occurs through mixing caused by turbulence created by wind, powered ventilation and machinery movements. The type and number of ventilation required to provide air in compliance with quality standards in workplaces depend on two factors; The speed of spread and dissipation of heat and pollution, the dilution of heat and pollution through ventilation or their removal from the environment. Two issues that are important to research and understand are; It is how heat and pollution mix and how clean air will dilute or remove heat and pollution from the environment.

There are three areas to be taken into consideration: determining the location of the air flow into or to be created within the working environment, determining the areas where the air currents will mix, and determining the areas where the air will be discharged from the environment.

There are two types of airflow: heat and dirty air from machines or work. Clean airflow from openings in the environment. Speed ​​of air flow; When it mixes with the surrounding air, it gradually accelerates or slows down depending on the air present in the environment.

If the speed of the air flow is the same as the speed of the existing air moving in the environment, the flow becomes unnoticeable. The areas where air leaves the working environment are windows, doors, ceiling fans, discharge gaps and grilles.

Although the density of the air coming out of such dischargers is high, its speed decreases near the air outlet. As a result, an airflow occurs around the openings that provide discharge. Therefore, breakthrough vents can disturb workers because they themselves create cross-drafts.

However, if breakthrough cavities are placed too close to the source, propagation over large areas is reduced. In addition to the principles of ventilation of heat, gases and dust, the rate of hot air pollution and its physical properties should be examined.

Density differences caused by heat cause different air currents to be displaced. When dirty gases and vapors are stationary, they are heavier than air, but when they encounter air, density differences become less obvious.

VENTILATION TYPES

Natural ventilation: Natural ventilation is used to dilute and distribute heat and polluted air.

Air escapes from any opening in the superficial boundaries of a space and is replaced by fresh air. Therefore, the hot or dirty air inside is diluted. It is difficult to determine the amount of natural ventilation that provides fresh air through infiltration, because this rate depends on the wind pressure from outside, the direction of the wind, the radiation of solar rays, the number and size of cracks on walls and roofs, and the moving air in the indoor environment.

As a result, the natural ventilation method has always been found useful to control the spread of dust and smoke. Thanks to this method, only very low density gas and steam can be controlled. This method is only used in environments where the ambient temperature is not high and there is no need for a different method.

Dilution ventilation: Dilution (powered) ventilation is used to replace natural ventilation. However, there must be high temperature and high gas and vapor density in the environment.

This is achieved by blowing air into the environment or by placing fans on the walls and ceiling. In both cases, heat and pollution are diluted and exhausted from the building.

Air conditioning; Air conditioning systems perform heating, cooling and humidification functions together. Meanwhile, some systems also eliminate air pollutants.

These systems are classified into three groups according to their operating principles. ◦ 1-Closed systems. ◦ 2-Semi-closed systems. ◦ 3-Partitioned systems.

Air conditioning systems are divided into two according to the areas they affect; ◦ A-For single fields, ◦ B-For multiple fields.

Common elements of air conditioning systems are: ◦ a- Heating and cooling unit ◦ b- Water or refrigerant gas ◦ c- Electrical or other fuel systems ◦ d- Humidity control unit ◦ e- Direct water vapor injection ◦ f- Condensation units ◦ g- Solids retention units

HEAT (AIR TEMPERATURE): Heat, salt, acid, base, sugar, etc. in the human body. Some physical and chemical values ​​such as must remain within certain limits. The human body has mechanisms in its structure that ensure and adjust these values ​​to remain within certain ranges. With these mechanisms, humans defend themselves against adverse environmental conditions and provide the opportunity to continue their lives even under adverse conditions.

One of these balances in the human body is heat (temperature). The temperature of a normal human body that is not sick is 36 degrees Celsius. Man is in constant communication with his environment. It is constantly affected by the conditions around it. One of the environmental conditions of humans is air temperature. If the air temperature in the environment is high, the human body begins to warm up due to heat transfer (heat transfer) from the hot environment to the cold environment.

The human body temperature should remain around 36 degrees Celsius. Otherwise, our fever will rise and we will fall into bed. If the ambient temperature is too low, the body's temperature begins to decrease due to heat transfer and we begin to freeze.

The human body tries to keep its body temperature constant by contracting and shivering when the air in the environment gets cold, and by opening up and sweating when the air gets warm, with defense systems whose details we do not know much about. However, when these defense mechanisms are working, people become bored and uncomfortable, and their work efficiency decreases. If environmental conditions are extremely deteriorated, the body can no longer defend itself, defense mechanisms fail or become insufficient, the person's balance is disrupted, body chemistry is disrupted and he/she becomes ill. It invites an accident.

In order for employees not to get bored, uncomfortable, sick, or to prevent their body chemistry from deteriorating, it is necessary to adapt the environmental conditions and the temperature in question.

AIR FLOW SPEED In order to throw out the dirty air in the workplace and replace it with clean air, it is necessary to have proper ventilation and therefore a suitable air flow. However, if this air flow exceeds 0.5 meters/second, disturbing breezes occur. Due to the damage caused by these breezes, we often encounter that ventilation systems are not operated in workplaces, especially in welding workshops, even though the air in the environment is polluted. In order to avoid such negativities, HEATING AND VENTILATION SHOULD BE UNDERSTANDED AS AIR CONDITIONING, and with this understanding, a project should be designed by taking all values ​​into consideration. Now let's focus on the relationships between temperature, humidity, air flow rate and radiant heat. ◦ An attempt was made to determine the conditions in which the majority of employees (80%) feel most comfortable in terms of heat sensation in workplaces. In this way, the concept of THERMAL COMFORT ZONE emerged. ◦ Thermal Comfort Zone; It is the region between the upper and lower limits of the thermal comfort conditions required for the employee to be in the most comfortable position during his activity. There are direct and indirect provisions regarding both ventilation and air conditioning in our occupational health and safety legislation. The main statutes and regulations that contain these provisions and the provisions mentioned are stated below. Former Worker Health and Occupational Safety Regulation - Source, Regulation on the Protection of Employees from the Dangers of Explosive Environments, which was issued based on the 74th article of the Law No. 1475, which was abolished in accordance with the temporary second article of the Law No. 4857, as a result of the gradual entry into force of Article 6331. Regarding the Health and Safety Measures to be Taken in Workplace Buildings and Attachments. Regulation on Health and Safety Measures in Working with Chemical Substances Regulation on Manual Handling Works Regulation on Health and Safety in Construction Works Old Occupational Health and Safety Regulation - Can be used as a resource. Article 8 The air volume in the workplaces will be at least 10 cubic meters per worker, including the volumes occupied by machinery, materials and similar facilities. When calculating the air volume, no more than 4 meters of the ceiling height is taken into account. Article 20 It is essential that the temperature and humidity in closed workplaces be moderate and appropriate to the nature of the work performed. It is said