Mechanical Engineers worldwide made standard codes in order to unify the mechanical systems in any building. Where mechanical engineers are obliged to calculate, size, and design according to these international standards. The most important used codes are ASHRAE which stands for American Society of Heating, Refrigerating and Air Conditioning engineers, NFPA which stands for National Fire Protection Association, SMACNA which stands for Sheet Metal and Air Conditioning Contractors? National Association, ASME which stands for American Society of Mechanical Engineers, and finally the IPC which stands for International Plumbing Code.
ASHRAE is the source of the standards which stands for the American Society of Heating, Refrigerating and Air Conditioning engineers. Foundedfounded in 1984 to serve as a source of technical standards and guidelines. Since that point, this organization promotes a code of ethics for HVAC professionals. one amongst the foremost vital functions of the organization is to promote analysis and development in economical, environmentally friendly technologies
Since that time, this organization promotes a code of ethics for HVAC professionals. One of the most important functions of the organization is to promote research and development in efficient, environmentally friendly technologies 10.
Founded in 1896, NFPA was founded in 1896 delivers information and knowledge through more than 300 consensus codes and standards, research, training, education, outreach and advocacy; and by partnering with others who share an interest in furthering our mission. NFPA membership totals more than 60,000 individuals around the world 11.
Sheet metal work dates back centuries, including its use in early home construction. It became critical for environmental control during the Industrial Revolution with the advent of heating, ventilation and air conditioning (HVAC) systems that maintain a comfortable air temperature and pressure, as well as provide air filtration. SMACNA International was founded in 1943, and SMACNA St. Louis began shortly after in the 1950s 12.
ASME is a not-for-profit membership organization that enables collaboration; knowledge sharing, career enrichment, and skills development across all engineering disciplines, toward a goal of helping the global engineering community develop solutions to benefit lives and livelihoods. Founded in 1880 by a small group of leading industrialists, ASME has grown through the decades to include more than 130,000 members in 151 countries. Thirty-two thousands of these members are students 13. ASME is a non-profit organization that permits collaborations; information sharing, career enrichment, and skills development across all engineering disciplines, toward a goal of serving the world engineering community develop solutions to profit lives and livehoods
The International Plumbing Code (IPC) is a proven, comprehensive model plumbing code that works seamlessly with ICC’s family of building codes. It sets minimum regulations for plumbing systems and components to protect life, health and safety of building occupants and the public. The IPC is available for adoption by jurisdictions ranging from states to towns, and is currently adopted on the state or local level in 35 states in the U.S. 14. The International Plumbing Code (IPC) is a tested, comprehensive model plumbing code that works seamlessly with ICC’s family of building codes. It sets minimum regulations for plumbing systems and elements to safeguard life, health and safety of building occupants and also the public.
To overcome the economic, environment, and manufacturability constraint, design catalogues were referenced in this project. Similar projects were also reviewed for feasibility studies. One of the goals of building design is to give people a safe and pleasant environment to live or to performance their tasks. This project has considered humidity level, indoor ventilation, toxic gas ventilation, etc. to meet the safety and comfort requirement. This project made its best effort to improve energy efficiency. An accurate load calculation was conducted at the beginning of the project, and the mechanical systems were designed based on the load requirement. An energy projection was conducted at the end to estimate the potential energy input requirement.
2.2. PROJECT PLAN
2.2.1. Heating, Ventilation, And Air Conditioning System (HVAC)
Heating and cooling loads are the measure of energy needed to be added or removed from a space by the HVAC system to provide the desired level of comfort within a space. Right-sizing the HVAC system begins with an accurate understanding of the heating and cooling loads on a space. Right-sizing is selecting HVAC equipment and designing the air distribution system to meet the accurate predicted heating and cooling loads of the house. The values determined by the heating and cooling load calculation process will dictate the equipment selection and duct design to deliver conditioned air to the rooms of the house. The heating and cooling load calculation results will have a direct impact on first construction costs along with the operating energy efficiency, occupant comfort, indoor air quality, and building durability. Heating and cooling loads are the measures of energy required to be value-added or removed from a space by the HVAC system to produce the specified level of comfort in a space. Right-sizing the HVAC system begins with a correct understanding of the heating and cooling loads on a space. Right-sizing is choosing HVAC equipment and designing the air distribution system to meet the correct expected heating and cooling loads of the house. The values determined by the heating and cooling load calculation method can dictate the equipment selection and duct design to deliver conditioned air to the rooms of the house. The heating and cooling load calculation results can have an immediate impact on initial construction prices in conjunction with the operational energy efficiency, resident comfort, indoor air quality, and building durability.
An HVAC designer can suggest different types of air-con systems for various applications
An HVAC designer will recommend different types of air conditioning systems for different applications. Choosing an HVAC system depends upon a number of factors strands including the area of the roomroom area to be cooled, the number of people inside the room, the total load heat generated inside the room, heating exchange and the temperature inside and outside the room. An HVAC designer would consider all the related parameters and suggest the most suitable system for a given space.
2.2.2. Device used in Cooling System
• Multi-split Type Air Conditioner (VRV or VRF):
VRV or VRF is a multi-split type air conditioner for commercial buildings (Fig.2.1) that uses variable refrigerant flow control to provide customers with the ability to maintain individual zone control in each room and floor of the building.
VRV or VRF is a multi-split type cooling system for commercial buildings(Fig.2.1) that uses variable refrigerant flow control to supply customers with the flexibility to keep up individual zone control in every space and floor of the building.
Figure ?2 1 Multi-Split Air Conditioner 17
2.2.3. Refrigeration cycle
2.2.3.1. Refrigeration
Refrigeration is a process of moving heat from one location to another in controlled conditions. The work of heat transport is traditionally driven by mechanical work, but can also be driven by heat. Refrigeration has had a large impact influence on industry, lifestyle, agriculture and settlement patterns. This system is one of the most effective cooling system since the running cost and electrical consumption cost has a higher effect than the investment price.
2.2.3.2. Principles of Refrigeration
• Liquids absorb heat once changed from liquid into gas.
• Gases gives off heat once changed from gas into liquid.
• Liquids absorb heat when changed from liquid to gas
• Gases give off heat when changed from gas to liquid.
For an air conditioning system to operate with economy, the refrigerant must be used repeatedly. For this reason, all air conditioners use the same cycle of compression, condensation, expansion, and evaporation in a closed circuit. The same refrigerant is used to move the heat from one area, to cool this area, and to expel this heat in another area. For an air con system to operate with economy, the refrigerant should be used repeatedly. For this reason, all air conditioners use an equivalent cycle of compression, condensation, expansion, and evaporation in a closed loop circuit. Identical refrigerant is used to move the heat from one space, to cool down this space, and to expel this heat in another outdoor space.
• The refrigerant comes into the compressor as a low-pressure gas, it is compressed and then moves out of the compressor as a high-pressure gas.
• The gas then flows to the condenser. Here the gas condenses to a liquid and gives off its heat to the outside air.
• The liquid then moves to the expansion valve under high pressure. This valve restricts the flow of the fluid and lowers its pressure as it leaves the expansion valve.
• The low-pressure liquid then moves to the evaporator, where heat from the inside air is absorbed and changes it from a liquid to a gas.
• As a hot low-pressure gas, the refrigerant moves to the compressor where the entire cycle is repeated.
Note that the four-part cycle is divided at the center into a high side and a low side This refers to the pressures of the refrigerant in each side of the system (Fig.2.2).Note that the four-part cycle is split at the middle into a high side and a low side this refers to the pressures of the refrigerant in both sides of the system (Fig.2.2).
Figure ?2 2 Schematic figures showing the refrigeration cycle 16
2.2.4. Cooling load: Sensible and Latent
The design cooling load (or heat gain) is the amount of heat energy to be removed from a house by the HVAC equipment to maintain the house at indoor design temperature when worst case outdoor design temperature is being experienced. There are two types of cooling loads sensible and latent cooling load.The sensible cooling load refers to the dry bulb temperature of the building and the latent cooling load refers to the wet bulb temperature of the building. In the summer, humidity influence in the selection of the HVAC equipment and the latent load as well as the sensible load must be calculated.
The design cooling load (or heat gain) is that the quantity of heat energy to be removed from a house by the HVAC equipment to keep up the house at indoor design temperature once worst case out of doors design temperature is being experienced. There are 2 types of cooling loads sensible and latent cooling load.
The sensible cooling load refers to the dry bulb temperature of the building on the other hand latent cooling load refers to the wet bulb temperature of the building. within the summer, humidity influence within the selection of the HVAC equipment and also the latent load also as the sensible load should be calculated.
? Factors that influence the sensible cooling load (Fig.2.3):
• Glass windows or doors.
• Sunlight striking windows, skylights, or glass doors and heating the space.
• Exterior walls.
• Partitions (that separate areas of various temperatures).
• Roofs.
• Air infiltration through cracks and holes in the building, doors, and windows.
? .Factors that influence to the latent cooling load:
• People occupants in the building.
• Equipment and appliances operated in the summer.
• Lights.
Figure ?2 3 Schematic figure showing the cooling loads components 15
2.3. PLUMBING SYSTEM
The plumbing system includes the water supply and distribution pipes, plumbing fixtures and traps, soil, waste and vent pipes, building drains and building sewers, including their respective connections, devices, and appurtenances within the property lines of the premises, and water treating or water using equipment.
2.3.1. Water Requirements
In any building the water storage is used for three demands: domestic and potable, firefighting and irrigation use. In our project the use of the water storage is for domestic and firefighting use.(Fig.2.4).
Figure ?2 4 Schematic diagram showing the use of the water storage in buildings 15
There are two kinds of water distribution systems in order to distribute water in the up to 10 floors building: direct and indirect. The direct system (Fig.2.5) is that the water obtained from the local public utility of water in the city through the water main pipes undergrounds the roads to each apartment in each floor of the building using a variable speed pump placed on the water main line. While the indirect system (Fig.2.5) the water obtained from the local water utility stored in the ground tanks and then pumped to the roof tanks through centrifugal pump and then from the roof tanks to each apartment with the presence of the gravity and booster pump.
Figure ?2 5 Schematic diagram showing the water distribution systems 15
The direct system (fig.2.5) is that the water obtained from the local public utility of water in the city through the water main pipes undergrounds the roads to each apartment in each floor of the building using a variable speed pump placed on the water main line. But it has a high running cost in addition to the non-availability of water in case the electricity was cut off which happens often here in Lebanon.
While the indirect system (fig.2.5) the water obtained from the local water utility stored in the ground tanks and then pumped to the roof tanks through centrifugal pump and then from the roof tanks to each apartment with the presence of the gravity and booster pump. The indirect system will insure water in the absence of electricity because of the tank that is found on the roof.
2.3.2 Roof tanks
The use of roof tanks to make sure adequate water pressure in buildings, and particularly tall buildings, is extremely common. the alternative to roof tanks is that the use of pressurized systems, where the presence of the booster pumps provides the required pressure.
Roof tanks enable the users to store water for domestic functions. Roof tanks vary greatly in size. once the water level in the tank drops below a definite level, the float switch engages the pump, refilling the tank. Roof tanks ought to be elevated enough on top of roof level to have enough pressure for the upper apartment. various materials are used for creating a water tank: plastics (polyethylene, polypropylene), concrete, galvanized steel.The use of roof tanks to ensure adequate water pressure in buildings, and especially tall buildings, is very common. The alternative to roof tanks is the use of pressurized systems, where a number of booster pumps provide the necessary pressure.
Roof tanks allow the users to storage water for domestic purposes. Roof tanks vary greatly in size. When the water level in the tank drops below a certain level, the float switch engages the pump, refilling the tank. Roof tanks should be elevated enough above roof level to have enough pressure for the upper apartment. Various materials are used for making a water tank: plastics (polyethylene, polypropylene), concrete, galvanized steel.
2.3.3. Centrifugal pump
A pump is a mechanical device that converts mechanical energy into hydraulic energy of the driving unit (electric motor, diesel, steam turbine, gas turbine, wind turbine … etc.). This hydraulic energy will increase the energy of the pumped liquid and enabled it to overcome the static head and hydraulic losses in the piping system within which the pump is interposed. Pumps enable fluid to:A pump is a mechanical device which converts mechanical energy of the driving unit (electric motor, diesel engine, steam turbine, gas turbine, wind turbine… etc.) into hydraulic energy. This hydraulic energy increases the energy of the pumped liquid and enabled it to overcome the static head and hydraulic losses in piping system in which the pump is interposed. Pumps Enable fluid to:
• Flow from the low-pressure region into one of high pressure.
• Flow from a low-level reservoir to a higher level reservoir.
• Flow at a faster rate circulates the water (hot water pump).
The pump is a rot dynamic pump (Fig.2.6) and works by creating kinetic energy. Its main part is that the impeller, which is truly the driving force behind the creation of kinetic energy. These are capable of discharging great amount of fluid being pumped-up. The impeller of the centrifugal pump is out there in both straight vanes and arced vanes to suit the pumping demand as the case may be. The pump isn’t a self-primed machine. It must be full of liquid initial so set to operate.
• Flow from a region of low pressure to one of high pressure.
• Flow from a low-level reservoir to a higher level reservoir.
• Flow at a faster rate circulates the water (hot water pump).
The centrifugal pump is a rot dynamic pump (Fig.2.6) and works by creating kinetic energy. Its main component is the impeller, which is actually the driving force behind the creation of kinetic energy. These are capable of discharging large amount of fluid being pumped. The impeller of the centrifugal pump is available in both straight vanes and curved vanes to suit the pumping requirement as the case may be. The centrifugal pump is not a self-primed machine. It needs to be filled with liquid first and then set to operate.
• Principle of Operation of Centrifugal Pumps:
The centrifugal pump converts one form of energy into another form to operate for pumping fluid. The energy changes due to two main parts of the pump, the impeller and the volute diffuser. The impeller is the rotating part that converts driver energy into the kinetic energy. The volute or diffuser is the stationary part that converts the kinetic energy into pressure energy, and this rise in pressure transfers some amount of energy to the discharge end too. Eventually when the pressure of the discharge end increases, the fluid is forced to move out via the discharge end and thus one pumping cycle is completed (Fig.2.6). The centrifugal pump converts one sort of energy into another form to operate for pumping fluid. The energy changes due to 2 main components of the pump, the impeller and the volute diffuser. The impeller is the rotating half that converts driver energy into the kinetic energy. The volute or diffuser is the stationary half that converts the kinetic energy into pressure energy, and this rise in pressure transfers some quantity of energy to the discharge end too. Eventually once the pressure of the discharge end increases, the fluid is forced to move out via discharge end and this one pumping cycle is completed (Fig.2.6)
Figure ?2 6 Centrifugal pump parts 15
2.3.4. Fixture units
Computing fixture units is a basic element of size piping systems for water distribution and drainage. Values assigned to specific types of fixtures are crucial within the sizing of a plumbing system. There are two kinds of ratings for fixture units:Computing fixture units is a fundamental element of sizing piping systems for water distribution and drainage. Values assigned to specific types of fixtures are crucial in the sizing of a plumbing system. There are two types of ratings for fixture units:
• Drainage Fixture Units
Pipes used to convey sanitary drainage are sized based on drainage fixture units. It is necessary to know how many fixture units are assigned to various types of plumbing fixture units. This information can be obtained, in most cases, from local code books. Not all plumbing codes assign the same fixture-unit ratings to fixtures, so make sure that you are working with the assigned ratings the specific region.
• Water Distribution Fixture units
Water distribution pipes are also sized by using assigned fixture-unit ratings. These ratings are different from drainage fixture units, but the concept is similar. As with drainage fixtures, water supply pipes can be sized by using tables that establish approved fixture-unit ratings. Most local codes provide tables of fixture-unit ratings. Two main types of plumbing serve house: water supply pipes and drain-waste-vent pipes. The water supply pipes are under pressure, but the drain-waste-vent pipes operate via gravity.
2.3.5. Water Heater
Water heating is a thermodynamic process that uses an energy source to heat water above its initial temperature (fig.2.8). Typical domestic uses of hot water include cooking, cleaning, bathing, and space heating.
Figure ?2 7 Schematic diagram for electric water heater 15
2.4. SANITARY DRAINAGE SYSTEM
2.4.1. Drainage system
A drainage system (drainage piping) includes all the piping within public or private premises, which conveys sewage, rain water, or other liquid wastes to a legal point of disposal. All sanitary drainage systems should be connected to the public sewer system (wherever available) at the nearest possible point.
2.4.1.1. Pipe system
• One Pipe System: The plumbing system in which the waste from sinks, bath rooms and wash basins, and soil pipe branches are all collected into one main pipe connected directly to the drainage system. Gully traps and waste pipes are completely dispensed with but all the traps of water closets, basins, etc. are completely ventilated to preserve the water seal.
• Two Pipe Systems: A discharge pipe system comprising two independent discharge pipes, one conveying soil directly to the drain, the other conveying waste water to the drain through a trapped gully. The system may also require ventilating pipes.this system might need ventilation.
2.4.1.2. Plumbing code systems
Plumbing or sanitation codes are set of rules and regulation imposed by city, countries or states. The codes are adopted and altered by the local authorities to fit local needs. Throughout the world different countries and jurisdictions have their local or common set of codes for different type of work. For the engineer it is always necessary to check and adapt the local regime. For example: plumbing code, international plumbing code (ICC), ASPE, DTU ….
2.4.1.3. Flush tanks and Flush valves
A flush tank and Flush valve is differentiated based on its application. Flush valve is used in public building, where water should be available for use instantaneously (for hospitals, malls…). Flush tank can be used in building where there is not that much rush into the toilets.
2.4.2. Vent
Sanitary drainage system of a building should be provided with an attendant system of vent piping designed so as to permit gases and odors in all parts of the drainage piping to circulate up through the system and escape into the atmosphere above the building and to permit the admission and emission of air in all parts of the system.
2.4.2.1. Vent stack
A vent stack is a vertical vent pipe installed primarily for the purpose of providing circulation of air to and from any part of the drainage system.
2.4.2.2. Vent system
A vent system is a pipe or pipes installed to provide a flow of air to or from a drainage system or to provide a circulation of air within such system to protect trap seals from siphon age and back pressure.
2.4.2.3. Traps
A fixture trap, illustrated in the accompanied figures, is a U-shaped section of pipe of the necessary depth to retain sufficient liquid required by code. All fixtures and equipment directly connected to the sanitary drainage system are required to have traps (Fig.2.9). All traps must be vented in an approved manner, except for specific conditions waived by local code requirements or authorities.
Figure ?2 8 Schematic figure showing the right installation of the vent 15
2.5. FIRE FIGHTING SYSTEM
The design of the fire protection system is made in accordance with the National Fire protection association without contradiction with local codes and regulations. Wet Riser (1″ Fire hose cabinet) is provided on lift lobby. Wet Riser (2 ½ “Landing valves) is provided inside each fire escape stairs. One Siamese (Fire Department) connection 2*2 ½”is provided at ground floor for fire brigade use. Sprinkler system is provided for all floors (residential and basements). Portable fire extinguishers are provided throughout the residents? floors and in the car parking areas with one extinguisher every 15 m of walking distance. As well as CO2 fire extinguishers on the door of the fuel tanks.
