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Assignment On
Submitted To:
A K M Sarwar Inam
Assistant Professor
Dept. of NFE
Faculty of Allied Health Science
Daffodil International University
Submitted By :
Fatema Hossain Takia
ID : (151-34-383)
Dept. of NFE
Faculty of Allied Health Science
Daffodil International University
Date of Submission: 18-03-2018
Prima facea, I’m grateful to the Almighty Allah for the good health and wellbeing that were necessary to complete this assignment.

I’m also grateful to A K M Sarwar Inam (Assistant Professor), in the Department of NFE. I’m extremely thankful to him for sharing expertise, and sincere, and valuable guidance and encouragement extended to me.

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I take this opportunity to express gratitude and veneration to all who have helped me doing this assignment. I also thank my parents for their unceasing encouragement, support and attention.

Table of Contents
Topic Name Page No.

Objective of air handling systems———————————4
Role of air handling systems in food industry——4
Air Handling Systems————————————————————5-9
Air handling system plays an important role in the quality control of air within factory buildings and industry. The nature about air inside plant structures may be controlled, By huge numbers nourishment Producers.Environmental air of a speci?ed quality(humidity, air flow, temperature, pressure and particle concentration)and quantity (fresh air volume) is required for the safety and comfort. To reduce the possibility of contamination and ensure the quality it is necessary to impose additional controls on environmental air quality. Properties of air, especially humidity, pressure and temperature, may be used to prevent or reduce the growth rate of some micro-organisms in manufacturing and storage areas. (Food-infonet, 2018)
Objective of air handling system:
Air handling systems are intended to maintain and achieve standard quality products.
To prevent contamination, ensure safety and quality.

To minimize cross-contamiination.

To facilitate processing, packaging and storage.

Role of air handling systems:
To control airborne particulates and odors and to minimize the risks to products from airborne contamination by infectious pathogens (e.g. E.coli Salmonella) and toxigenic pathogens (e.g. Staphylococcus aureus) and spoilage microorganisms (e.g. yeast, molds, pseudomonads and lactic acid bacteria).

To control airborne contamination, the following variables are important to the speci?cation of the air handling system:
1.Temperature: When higher temperatures would be harmful to food safety then the temperatures below 13C should only be used.

2.Air distribution: To provide suf?cient fresh air,to remove the heat imposed by the processes and people,prevent the airborne contamination. (Food-infonet, 2018)
Air Handling Systems:
1. HVAC Systems: Heating Ventilation and Air Conditioning systems are the integral part of environmental control system design, basic components of HVAC includes air handling unit, air distribution, air filters. (Slidesharenet, 2018). Its purpose is to maintain the heat, ventilation, air conditioning at the desired level. HVAC systems are located in the interstitial places between the building floors. Basic function is to volume control,temperature control and pressure control. A proper HVAC system will provide an improved indoor environment, quality air and minimize the cost of operation.

2. Air Handling Units: AHU is a device used to condition and circulate air as part of a heating ventilating and air conditioning (HVAC) system. It is a primary equipment of the air system. It is a large metal box containing a blower, heating or cooling elements, filter racks or chambers, humidity and temperature control loops, sound attenuators-connects to duckwork that distributes the conditioned air through the building and return it to the AHU. In food industry arrange AHU separately to each floor or to the whole buildings. (Slidesharenet, 2018)
3. Air filtration systems: Filtration is an important aspect of environmental control in food industry. The main aim of filtration is to produce dust free atmosphere where the products can be handled in clean conditions or for the development of controlled sterile environment for many aseptic processes. It is required in areas such as spray drying, granulating, coating, milling and packaging. Based on the required environment filters are selected. Air filtration involves the removal of unwanted particles due to collision of particles with the filter are governed by forces called impingement, diffusion, interception (these forces are not applicable for very small particles). Types of air filters includes:
Ultra low penetration and high efficiency particulate air filters (ULPA and HEPA).

Packed towers.

Membrane filter catridges.

Hydrophobic filters. (Slidesharenet, 2018)
Electrostatic filters ( Air filters that collect and retain dust by means of an electrical charge can be divided into three types:
Electrostatic air cleaners that are filter devices installed into air conditioning and ventilation systems.

Electrostatic precipitators that are installed to collect such items as flyash from the extract air on power stations.

c. Electret filters which are passive electrostatic filters. (Food-infonet, 2018)
4. Humidity control: Comfort humidity levels are in the range of 45-55% RH. Air dryers should be used to maintain lower than normal humidity levels. (Slidesharenet, 2018). In the food industry humidity problems are generally caused by too much water in the air rather than too little. In air conditioning systems both may be used. To facilitate processing,storage and distribution within the food industry, humidity must be controlled.

a. Humidification: Humidification may be achieved by one of the following methods:
Atomisation of water into the air flow by a rotor.

Air washing by a spray.

Injection of steam.

Evaporation from a rotating wheel partly immersed in a water tank.

b. Dehumidification: Dehumidifiers remove water from the air. The most common method is to pass the air across a cooling coil and as the temperature of the air falls, the water condenses on the coils and then drains away. After the cooling coil, the air is then heated to bring it back to the required operating temperature. The main problem is again microbial growth in the water that condenses in the cooling system. The cleaning and disinfection of cooling coils must be included as part of the overall plant hygiene programme. (Food-infonet, 2018).
A combined dehumidification-ventilation system can bring in fresh (but humid outdoor air), remove moisture, and supply it to the industry. (Ukyedu, 2018)
5. Temperature control: The most basic type of control system is a heating and cooling thermostat. Programmable thermostats, also called setback thermostats, which can be big energy savers for industry. These programmable thermostats automatically adjust the temperature. The programmable thermostat selected is designed for the particular heating and cooling equipment it will be controlling. A thermostat should be located centrally within the area or zone. It should not receive direct sunlight or be near a heat-producing appliance. A good location is often 4 to 5 feet above the floor in an interior hallway near a return grille. The interior wall, on which it is installed, should be well sealed at the top and bottom to prevent circulation of cool air in winter or hot air in summer. (Ukyedu, 2018)
Temperatures in the range of 19-23C (68-74F) is comfortable for working environment. Temperature control is important in the areas where ovens, autoclaves, dry heat sterilization tunnels are present. (Slidesharenet, 2018)
Temperature is one of the factors that can be used to manage the number of microorganisms that may be present in a food product and may cause spoilage. Temperature is a well known management tool to keep bacteria levels low and prevent or reduce spoilage. Temperature should be maintain during receiving, storing, preparing, and serving. For example, the temperature for all hot foods must be held at 135F or higher and for all cold foods must be held at 41F or below. The temperature danger zone is between 4-60C (41-135F). Good temperature control is being achieved throughout the cold food chains as a result of improved equipment design, quality control. Temperature monitoring system to maintain the appropriate storage conditions, ensure appropriate conditions for processing, retailing/foodservice. (Yahoocom, 2018)
6.Ventilation Systems: All food industries need proper ventilation to remove stale interior air and excessive moisture and to provide oxygen for the inhabitants. There has been considerable concern recently about how much ventilation is required to maintain the quality of air in food industry. Heat Recovery Ventilators Air-to-air heat exchangers, or heat recovery ventilators (HRV), typically have separate duct systems that in outside air for ventilation and distribute fresh air throughout the industry. (Ukyedu, 2018)
A good air handling system must be complemented by a building of good design.Building design in food industry may consider sufficient ventilation system.Some types of fans are used for ventilation which includes-
a.Centrifugal Fans. ( e.g. Forward curved, backward curved )
b.Axial Flow Fans. ( e.g. propeller type, tube type, vane type ). (Yahoocom, 2018)
7. Dust collectors: Dust collectors are used for equipment maintanance and air pollution controlled. It is used for the protection of the operator, production equipment, quality of environment in a premises from dust. It also be used to prevent environmental pollution, accumulation of dust which may provide a substrate for growth of micro-organisms, and a supply of food for rodent and insect infestations and explosion. The filters used for dust control are quite different to those used for environmental air. Environmental air filters should not be used for dust control.

DCCs are mainly used for pre-cleaning and to improve the quality of air inside the plant. Types of dust collectors includes-
Dry mechanical collectors ( e.g. gravity seperators, inertial seperators, high efficiency centrifugals, cyclone collectors ).

Wet collectors and scrubbers ( spray dryer, wet centrifugal collectors, venturi type)
Electrostatic precipitators (ESP). ( e.g. cottrell, penny )
Fabric collectors. (Slidesharenet, 2018)
Gaseous contaminant collectors ( absorbers, adsorbers, thermal oxidizers, catalytic oxidizers, direct combustors).

Unit collectors ( having capacities in the range of 200-2000cfm ). (Yahoocom, 2018)
8. Clean room: Clean room is a room in which the concentration of airborne particles is controlled.It is constructed and used in a manner to minimize the introduction, generation and retention of particles inside the room. In this room the relevant parameters, e.g. temperature, humidity and pressure are controlled as necessary for the quality air. General Cleanroom Design incudes HEPA/ULPA filters on ceiling exhaust vents on floor drains in aseptic processing areas are inappropriate airlocks and interlocking doors to control air balance Seamless and rounded floor to wall junctions Readily accessible corners floors, walls, and ceilings constructed of smooth hard surfaces that can be easily cleaned Limited equipment, fixtures and personnel layout of equipment to optimize comfort and movement of operators. (Authorstreamcom, 2018)
9. Aseptic systems: Products that are usually microbiologically ambient stable in the ?nal sealed package aseptic ?lling systems are used for those. To operate very high standard microbiological safety to ensure minimum probability that product units will be contaminated, aseptic systems are required. For ensuring ?nal air quality in a food processing environment the air supplied should be ?ltered and equipment must be sterilized after each operating cycle, or when the integrity of the sterile zone is being lost. The air system may be decontaminated using chemical sterilant that must be removed before production starts. The volume of sterile air delivered by the air supply system must be suf?cient to maintain an adequate overpressure and out?ow of air, usually speci?ed by the manufacturer of the aseptic system. The air supply system must be adequate for all operating conditions. (Food-infonet, 2018)
10. Split-system units: Split-system units are generally used in larger air-conditioning application.A Split-system air conditioner splits thehot side from the cold side of the system.The cold side, consisting of the expansion valve and the cold coil, is generally placed into a furnace or some other air handler. The air handler blows air through the coil and routes the air throughout the building using a series of ducts. The hot side, known as the condensing unit, lives outside the building. The unit consists of a long, spiral coil shaped like a cylinder. Inside the coil is a fan, to blow air through the coil, along with a weather-resistant compressor and some control logic. (Yahoocom, 2018)
Air handling system plays a central role in the food industry. Hygienic air quality for the food industry is ensure by appropriate air handling system. It must be treated as a critical system. When setup a food industry air handling system must be designed properly by professionals.
1. Authorstreamcom. (2018). AuthorSTREAM. Retrieved 18 March, 2018, from
2. Food-infonet. (2018). Food-infonet. Retrieved 18 March, 2018, from
3. Slidesharenet. (2018). Slidesharenet. Retrieved 18 March, 2018, from
4. Ukyedu. (2018). Ukyedu. Retrieved 18 March, 2018, from 7 Heating Ventilation Air Conditioning.pdf
5. Yahoocom. (2018). Yahoocom. Retrieved 18 March, 2018, from;_ylt=Awr9KRS0Dq1alvIA8VcPxQt.?p=handle temperature in food industry ppt

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