Unit 8 Plant Auxiliary Systems Flashcards
Luminaire
A complete lighting unit, including the lamp, a voltage controlling device or ballast and is the means of light control (reflector or refractor)
Luminaires provide
Direct or indirect lighting or a combination of the two
Four types of Luminaires
Recessed troffer, surface mounted wrap arounds, open reflectors, structural lighting
Recessed troffer
Rectangular light fixtures that fit in grids or recessed ceilings. They have Prismatic panels that distribute light. Commonly used for General lighting in offices and Commercial Interiors.
Ceiling mount wraparound
Fluorescent fixtures that are mounted directly on the ceiling or wall surface. Clear Prismatic plastic covers that surround the lamp. Give broad light distribution, inexpensive and efficient. May appear too bright in many installations
Open reflectors
Serve as Shields to partially screen the lamps from View. Used in industrial installations or in storage areas of commercial buildings
Structural Lighting
Fitted into Architectural Components of a room
Three main types of Illumination
General (uniform)
Local (supplementary)
Combined general/local
General illumination (uniform)
Designed to provide uniform illumination throughout an area. Used in most offices since it is difficult to predict the location of workstations, which require more lighting. Luminaires are spaced at regular intervals
Local or supplementary illumination
Used to illuminate work areas or displays regardless of the overall uniform ambient light.
Ex; track lighting that illuminates wall displays
Combined general/local (non-uniform or task lighting)
Provides reasonable lighting level. In addition an effort is made to identify specific work areas to increase their illumination levels. Requires more design work, but will be more energy efficient than a uniform system. More difficult to alter the lighting system if the room is rearranged
Direct lighting
All or most of the Luminous intensity is directed down, toward the work area
Indirect lighting
All or most of the Luminous intensity is directed up, at the ceiling. Light reflected off the ceiling, arrives at the work area indirectly
Direct lighting advantages and disadvantages
Advantages; more energy efficient, low initial cost, lower floor to ceiling height possible, easier to control and direct
Disadvantages; harsh Shadows, potential for direct glare, greater potential for ceiling Reflections and reflected glare, excessive luminance and glare
Indirect lighting advantages and disadvantages;
Advantages; potential for maximum Visual Comfort, greater glare control, Blends in with environment, produces uniform shadow free light
Disadvantages; less energy efficient, requires a uniform unobstructed reflecting sealing surface, increase in building cost, electrical installation may be more expensive
Incandescent light
One of the oldest developed light sources. Electrical current passes through a wire filament inside a glass bulb or globe. Filament glows and emits visible light
Main reason for coated glass
To distribute light evenly. Coding can also be colored
Halogen lamp
Type of incandescent light. Bulb is filled with halogen gas to prolong life of filament. Halogen provides a brighter light emission than typical incandescent lights. Operates at higher temperature then regular incandescent light.
Incandescent light luminous efficacy
Low ratio of energy to light emission efficiency. Most energy supplied to produce light is converted to heat.
Fluorescent lights
Type of gas discharge light source. Filled with mercury vapour. Electrical current is applied to the gas, producing ultraviolet light. The UV light then causes the phosphor coating inside the tube to Glow White. Consumes less energy than incandescent light.
Straight tube fluorescent light
All require external ballasts to work
Two types of compact fluorescent
Screw in and plug in. Both operate the same way as straight tube fluorescent lights
Screw in compact fluorescent light
Has an integrated ballast. Simply screws into existing electrical sockets
Plug-in compact fluorescent light
Requires a ballast and a socket that corresponds to a specific base configuration
High intensity discharge (HID)
Type of electric gas discharge light. Produces light when an arc passes between two tungsten electrodes inside a transparent quartz tube filled with metal salts and gas. Gas is used to assist with the Arc. Arc heats the metal salts that evaporate and form plasma. Can admit a large amount of light with relatively low energy consumption
HID primary uses
High ceiling applications. Like gymnasiums, warehouses and street lights. May require extended warm up time and not suitable for interrupted services
Mercury vapour light bulb
Type of HID light. Operates similar to hid but uses mercury vapour inside a pressurized glass tube coated with phosphor
Sodium vapour light
Type of gas discharge light. Similar to mercury vapour bulb except utilizes sodium gas inside a pressurized glass tube.
Two types of sodium vapour light
Low pressure and high pressure sodium
Light emitting diode (LED)
Semiconductor device that allows electric current to flow in One Direction only. Emit light when a suitable amount of electricity is applied across the leads. They have been steadily replacing other artificial light sources
High Luminous efficacy
Low energy cost with high ratio of energy to light emission efficiency
LED light disadvantage
The initial Purchase cost
Wattage
Amount of electrical energy consumed by the lamp to produce light
Lumen or luminous flux
Metric unit for total quantity of light emitted by a light source. The more lumens emitted by a light source, the brighter the light
Light colour is measured in
Units of absolute temperature (kelvin). Lower temperature light is more yellow. Higher temperature light is Bluer
Line voltage lighting system
Only uses line voltage rated controls and wiring. To control lighting it requires the use of 3-way and 4-way switches
Low voltage switching
Uses low voltage relays to control lighting from multiple locations
Low voltage switching advantages
Local and remote control of Lights, Reduction in installation cost, higher voltage lighting, alteration work is simpler, low voltage relays can be operated by programmed distributed control systems
Cadmium sulfide cell
Placed in series with a holding coil of a normally closed relay. As the illumination level drops, the resistance of the cell increases and the current through the relay decreases. When light level reaches the control setting, relay contacts close and light is energized
Timer for time clock
Device that energizes or D energized has a light out of preset time.
Two types of timers or time clock
Electromechanical or electronic
Electro mechanical time clock
Electric clock Motors that move a series of adjustable engagement dogs to turn the lights on or off at designated times
Electronic timers
Use microprocessor controls and switches to achieve the same result
Occupancy sensors
Turn the lights on when people enter a room, and off when they leave after a set time. Most effective in spaces with transient activities, where the lights are easily forgotten.
Occupancy sensors can reduce lighting costs by
20 to 60%. The sensors can pay for themselves in less than 2 years.
Areas where occupancy sensors are used
Conference and meeting rooms, hallways, washrooms, storage rooms, warehouses
Two most common types of occupancy sensors
Infrared and ultrasonic detectors
Infrared motion detectors
Respond to heat. They sense changes in patterns of heat radiated of objects warmer than their surroundings. Only receives a signal from within a line of sight
Ultrasonic motion detectors
Detect motion with ultrasound. Sends out an inaudible tone, capable of bouncing off walls and round corners. The returning tune is compared with the tone sent out. Any change in frequency indicate occupancy. Will turn on from any motion from person or object
When selecting an occupancy sensor, important factors to consider
Area coverage, beam pattern, and false triggering.
Infrared occupancy sensor disadvantage
May consider a mirrored image or daylight as a signal that space is occupied
Ultrasonic occupancy sensor disadvantage
May be triggered by vibrations
The most effective means of controlling the level of Illumination
By use of a dimmer
Solid-state dimmers
Reduce the average voltage across the lamps by turning on or off at a particular instant
Fluorescent and HID dimmers require
Special dimming ballast and special dimmers, not interchangeable with regular incandescent dimmers
Emergency lighting must be powered by
Battery or a standby generator
Emergency lighting must provide adequate lighting Within
10 seconds and remain on for 90 minutes
In large Office Buildings the percentage of electrical energy consumption used by the lighting system
60%
Energy savings can be gained by reducing the illumination levels
In areas adjacent to the task areas requiring higher levels of Illumination
Lamp efficacy is expressed by
Lumens per watt
Luminous efficacy is a pure ______
Ratio and expressed in percent
The suitability of a lamp for a particular application is influenced by these factors
4
Life expectancy, colour rendition, cost, warm up time
Energy saving lamps
Bulbs can be replaced with clear dummy bulbs that provide no light but allow the circuit to function normally. Used in areas with excess fluorescent light
High-efficiency fluorescent ballasts
Decrease wattage losses within the steel core and copper windings. Can reduce energy consumption by 9%. Ballast life is two to three times longer
Reduced light output ballast
Decrease energy consumption by reducing the amount of current to the lamps by as much as 20%
Solid-state ballast
Use much less power than conventional ballast
As interior surfaces become less reflective
The amount of energy required to illuminate a room increases
Coefficient of utilization (CU)
The percentage of light that arrives on the work plane. Important consideration in an energy efficient installation
Key points for maintenance in a lighting system
2
Relamping and cleaning
Relamping
All lamps replaced at a pre-planned time. Usually done at 70% of rated life. Can mean a considerable amount of reduction in labour costs
Dirty lights can drop light output by
5% per year. Cleaning is required from once a year to once every three years
Most Municipal Water Systems distribute water at pressures between
350 kPa and 490 kPa
In cases where tall buildings require higher pressure, _____ are used
Pumps
Highest and lowest permissible pressure in Plumbing Systems
560 kPa and 175 kPa
Water demand load for a building plumbing system is determined by
Adding up the maximum flow rate of the total number of Plumbing fixtures used in the system
Two methods water may be distributed throughout a building
Up feed systems and down feed systems (gravity)
Four common up feed water systems
Direct pressure, tankless constant pressure, constant pressure with suction tank, constant pressure with pneumatic tank
Direct pressure system
Water is obtained directly from Municipal Distribution Systems at 350kpa. Water flows through a water metre in the basement and then through a horizontal water main
Tankless constant pressure system
Used when supply pressure to a high rise building is too low to provide enough water pressure on the Upper Floor
When two water pumps are used, each pump must be capable of supplying
70% of the maximum flow demand
When three water pumps are used, two pumps must each have sufficient capacity to supply
55% of the maximum demand, and the third 25%
In a two pump system, one pump is usually
In continuous service while the second is on standby
Two situations where a surge or suction tank should be used
Water flow from the supply source is not adequate to meet maximum demand for building
Maximum building demand could cause water pressure in the supply source to drop too low
During periods of extremely low water demand, a pressure relief device
Bypasses the flow back into the tank and prevents the pump from overheating
Generally pumps are operated under low
Suction head and must be capable of providing a greater discharge head, this results in higher electric power consumption
Pump suction should always be above
The bottom of the tank to prevent sediment from being discharged into the system
Down feed or gravity systems
Have a storage or house tank above the highest fixture in the building. Provide storage capacity for the potable water systems in situations where the supply flow may be too low.
Two methods of hot water supply systems for buildings
Non circulating hot water system and circulating hot water system
Non circulating hot water system
Has a single pipe through which the heated water passes from a water heater to each fixture in the building.
Non circulating hot water systems are normally used
In small residential buildings with short runs of pipe less than 15 m in length
Circulating hot water systems
Have a return line connected near the end of each hot water main leading back to the water heater. Provides hot water at each fixture with shorter delays, resulting in less waste
Circulating hot water systems are used
In all types of buildings where the fixtures are a long distance from the central heating source
A circulating hot water system consists of these three things
A heater, Supply piping to carry hot water to the fixtures, return piping to return the unused water back to the heater
A ______ must be installed in the return line
Check or backflow valve which prevents cold water from entering the hot water lines when there is maximum flow from the fixtures at the end of the hot water supply
Two types of hot water heaters
Direct and indirect
Direct hot water heaters
Water is heated by a burning fuel or an electric element
Indirect hot water heaters
Heated by steam or high temperature water from a heating system
Instantaneous water heater
Direct fired heater that does not require a storage tank because the water is heated instantly as it flows through the tubes.
Aquastat
Thermostatic controlling device, regulates the ratio of the two Flows at the mixing valve. Maintains the proper hot water temperature.
Temperature and pressure relief valves
Installed on the uppermost part of heaters. Release water pressure if the temperature of the water becomes too high due to malfunction of the system
Temperature regulator
Consists of a bulb, capillary, and a valve actuator Bellows filled with a volatile fluid. Can be equipped with a thermowell to permit removal of the bulb without draining the heater
Hot water system safety devices
Prevent dangerously High pressures and temperatures from developing in the system
Hot water system pressure relief valve typically opens at
175 kPa or 25 psi above-normal line pressure
Typically a relief valve is installed in the______
Hot water discharge line
If water is heated to above 100 degrees Celsius in a pressurized system, it will become a super saturated liquid. If the water pressure is reduced,
The super saturated water will flash into steam
Temperature relief devices open when the water temperature rises to about
99 degrees Celsius
If the hot water system includes a hot water tank, it will be equipped with
A drain valve at the bottom. To remove excess scale deposits, two or three pills of water should be drained every two to three months
High-limit energy cut off
Thermostat that shuts off the heat to the water heater when the maximum temperature has been reached
Backflow
Backwards flow of water or other liquids and gases into the Distributing pipes of a potable water supply
Backsiphonage
Caused by pressure that is below atmospheric in the supply system
back pressure
Results from a downstream pressure in the piping system that is higher than the upstream or supply pressure
Cross connection
Any actual or potential connection between the potable water supply and any other source or system through which it is possible to introduce contaminants into the water system
Air gap backflow prevention
Physical separation between the free-flowing discharge end of a potable water pipe and an open, non-pressurized vessel
Every Plumbing fixture in a building receives pure water and usually
Discharges it at some lower point
To allow for inspection and maintenance, larger storage heaters are fitted with
Manholes
Large hot water storage tanks and heaters are
Confined spaces
Insulation maintenance for hot water systems
Checking and patching insulation on the heater, steam lines, and hot water lines, otherwise heat can be lost via
Almost all faucet leaks are caused by
Failure to turn the faucet completely off after use, eventually the rubber washer inside wears out
Hush tube
The filler tube on the ballcock. Extends almost to the bottom of the tank and reduces noise by preventing splashing
Refill tube
Extends from the ballcock to the Overflow reseals the bull after Flushing
To prevent cross connection
Adjust the float rod so the water level does not come above the ballcock
Two types of flush valves
Diaphragm and piston
Horizontal Branch piping
Used to convey waste from fixtures throughout a building to a waste or discharge stack. This piping must be designed so that flow is not interrupted
In horizontal Branch piping, each branch connection to the discharge stack should have a
Long turn elbow that meets the vertical stack at an angle of 45°. Should maintain an adequate slope and size to maintain a minimum flow velocity of 0.6 metres per second
Traps
Their purpose is to seal the outlet of a fixture from the drainage piping so that sewer gases do not enter the building
Clean out plug
Usually located at the bottom of a trap to clean it out
Traps are often installed at
The end of a long length of horizontal piping before a floor drain
In a hot water system, the pressure relief valve may be installed
Close to the heater or tank
How often must backflow preventers be tested
Annually
Ambient lighting can be improved by two types of lighting
Direct or indirect or a combination of the two
In an indirect hot water heater, the thermostatically controlled valve is used to control
Steam flow. The valve increases steam flow when the water temperature drops below the desired value
