T1:  Measuring point for compressor acceptance test. Temperature at the compressor inlet flange.

T3:  Measuring point for compressor acceptance test. Temperature before an orifice or nozzle, downstream of compressor discharge.

TAB (Testing, Adjusting and Balancing): Ensures an HVAC system is performing efficiently.

Tail Beam: A relatively short beam or joist supported in a wall on one end and by a header at the other.

Tailings or Mine Tailings: Crushed waste rock deposited on the ground during mining and ore processing, including some of the rock in which the ore is found. Unless they are handled carefully, they frequently release contaminants. As they age under the effects of air, rainfall and bacteria, some oxidize to produce new toxic materials, such as sulfuric acid, that can leach out and poison streams, rivers and lakes.

Tailings Pond:  An excavated or diked area that is intended to contain liquid and solid wastes from mining and milling operations.

Tailpiece: The tubular part of a lavatory drain that runs from the drain flange to the trap.

Tailwater:  Applied water which drains as surface flow from irrigated lands.

Take Off: The material necessary to complete a job.

Talk-Thru:  A talk-thru is a special, covered opening in the cleanroom wall that allows people outside to talk to those inside without entering the room and causing contamination. Standard membrane and electronic talk-thrus are common.

Tangential (Crossflow) Filtration:  See Crossflow (Tangential) Filtration.

Tankless Water Heater:  A water heater that heats water before it is directly distributed for end use as required; a demand water heater.

Tape Sampler: A device used in the measure of both gases and particulates. It allows air sampling to be made automatically at predetermined times.

Taped Duct Test (TDT): A procedure using the blower door to measure the "potential" for leakage reduction of the duct system. All supply registers and return grills are taped shut following the initial blower door reading and a subsequent air leakage test taken.  If closing off the duct system in this manner causes an appreciable reduction in the air leakage rate, this is an indication that there are significant duct leaks.

Taping: Applying joint tape over embedding compound in the process of joint treatment of drywall.

Tare: A deduction of weight, allowing for the weight of a container or medium; the initial weight of a filter.

Task Ventilation:  The ventilation serving a localized area, such as a desk, generally through equipment with local controls for airflow rate, direction, etc.

Taste Threshold:  The minimum concentration of a chemical in the air that someone can detect by sense of taste; expressed in ppm.

T Bar: A ribbed “T” shaped bar with a flat metal plate at the bottom that is driven into the earth. Normally used with chain link fence poles, and to mark locations of a water meter pit.

TB Control Measures: Steps taken to reduce the risk of TB transmission. TB control
measures are divided into a hierarchy: (1.) administrative (work practice) controls, (2.)
environmental controls, and (3.) respiratory protection controls.

TBS:  Treasury Board of Canada Secretariat.

TC:  Transport Canada.

TCF: Trillion cubic feet, a measurement used to define the production of natural gas.

T Cells:  The T cells are cells derived from the thymus that play a major role in a variety of cell-mediated immune reactions. (B cells are also important in immunity because they synthesize and secrete antibodies which protect animals from infection, viruses, etc.)

Tear-Off: In roofing, a term used to describe the complete removal of the built up roof membrane and insulation down to and exposing the roof deck.

Technical Advisory Group (TAG):  Subcommittees that consist of industry experts who assist in developing credit interpretations and technical improvements to the LEED system.

Technical Nutrient:  A material designed to return into the technical cycle.

Technosphere:  The portion of the biosphere which has been altered or influenced by human activity.

Teco: Metal straps that are nailed to secure the roof rafters and trusses to the top horizontal wall plate. Sometimes called a Hurricane Clip.

Tee: A T-shaped fitting with three openings.

TEFC (Totally Enclosed, Fan Cooled): Totally enclosed motors equipped with a cooling fan to prevent overheating.

Telecom Cabinet:  A tall cabinet used to telecommunications equipment and systems.

Telescope Reach System:  This is the Dyson system of “on-board” attachments that has no awkward parts to assemble for above the floor and high reach cleaning.

Telescopic Wand:  This is a wand design that allows the user to set the wand length that is most comfortable for his or her height, usually on a variable basis to the wand’s full extension.

Temperature: The thermal state of matter with reference to its tendency to communicate heat to matter in contact with it

Temperature, Dewpoint:  The temperature at which the condensation of water vapor in a space begins for a given state of humidity and pressure as the temperature of the vapor is reduced. The temperature corresponding to saturation (100 percent relative humidity) for a given absolute humidity at constant pressure.

Temperature, Dry-Bulb:  The temperature of a gas or mixture of gases indicated by an accurate thermometer after correction for radiation.

Temperature, Mean Radiant (MRT):  The temperature of a uniform black enclosure in which a solid body or occupant would exchange the same amount of radiant heat as in the existing non-uniform environment.

Temperature, Saturation:   The temperature at which no further moisture can be added to the air-water vapor mixture. Equals dew point temperature.

Temperature, Wet-Bulb:  Thermodynamic wet bulb temperature is the temperature at which liquid or solid water, by evaporating into air, can bring the air to saturation adiabatically at the same temperature. Wet bulb temperature (without qualification) is the temperature indicated by a wet bulb psychrometer constructed and used according to specifications.

Temperature Absolute:  The temperature of a body referred to the absolute zero, at which point the volume of an ideal gas theoretically becomes zero. (Fahrenheit scale is minus 459.67°F / Celsius scale is minus 273.15°C).

Temperature Control:  Typical refrigeration and air conditioning systems control temperature by on/off compressor cycling as air temperatures fluctuate between minimum and maximum thermostat settings. Compressor start-up often introduces substantial transient noise into the circuit powering the equipment to be cooled. Thermostat or relay operation results in electromagnetic interference. Both of these factors can adversely affect the function of electronic equipment. On/off compressor control necessitates choosing between large temperature excursions or frequent compressor cycling.  Furthermore, frequent start/stop operation exposes internal compressor components to electrical and mechanical strains not encountered during continuous operation. The use of electrical controls to handle high compressor start-currents results in eventual erosion of the control contacts themselves.  In order to eliminate the possibility of these problems, air conditioners feature a continuously operating compressor and non-electric proportional control system, which result in more stable equipment temperatures and prolonged life for the compressor and the control system. Both blowers and the compressor start simultaneously with the application of power to the unit, and continue to operate until power is removed at the time of equipment shutdown.  The Hot Gas Bypass Control Valve permits refrigerant to be injected into the evaporator coil. This high-temperature gas presents an artificial heat load and permits the effective cooling rate to be varied as necessary to maintain a constant return air temperature back to the enclosure. This control also prevents evaporator freeze-ups during periods of low heat load or low ambient temperature.  Although the above control system works effectively at most times, there are instances of over-cooling due to low heat load or low ambient temperature. In order to prevent that condition, Low Temperature Control thermostats and EMI/RFI suppressors have been added to all air conditioners.  When activated, the Low Temperature Control shuts off the compressor and condenser (ambient side) blowers. The evaporator (enclosure side) blowers continue to circulate the air through the enclosure and air conditioner. When the air temperature again reaches the level at which cooling is needed, the compressor and condenser blowers resume operation.

Temperature-Control Lag:  The delay of action of the temperature response element due to the time required for the element to reach the surrounding temperature.

Temperature Difference, Diffusion: Temperature difference between the air temperature at supply opening and design outdoor temperature.

Temperature Difference, Effective: Difference between the room air temperature and the supply air temperature at the outlet to the room.

Temperature Difference, Mean: Mean of difference between temperatures of a fluid receiving and a fluid yielding heat.

Temperature Discharge:  Is the temperature existing at the discharge port of the compressor.

Temperature Inlet:  Is the temperature at the inlet flange of the compressor.

Temperature Intake:  The total temperature at the intake flange of the compressor.

Temperature Inversion: One of the weather conditions that is often associated with serious smog episodes in some portions of the country. In a temperature inversion, air does not rise because it is trapped near the ground by a layer of warmer air above it. Pollutants, especially smog and smog-forming chemicals, including volatile organic compounds, are trapped close to the ground. As people continue driving, and sources other than motor vehicles continue to release smog-forming pollutants into the air, the smog level keeps getting worse.

Temperature Rise Ratio:  Is the ratio of the computed isentropic temperature rise to the measured total temperature rise during compression.

Temperature Static:  The actual temperature of a moving gas stream. It is the temperature indicated by a thermometer moving in the stream with the same velocity as the stream.

Temperature Swing (Indoor): The range of indoor temperatures in a building (K).

Temperature Swing (Outdoor): The range of outdoor temperature between day and night.

Temperature Total:  The temperature which would be measured at the stagnation point if a gas stream were stopped, with adiabatic compression from the flow condition to the stagnation pressure.

Temperature Standards: Recommended values for temperature (and other environmental parameters) in buildings or rooms, values generally defined by the expected use of the room.

Temperature Zones:  In HVAC individual rooms or zones in a building where temperature is controlled separately from other rooms or zones.

Tempered: Strengthened. Tempered glass will not shatter nor create shards, but will “palletize” like an automobile window. Required in tub and shower enclosures, entry door glass, sidelight glass and in windows where the window sill is less than 16” to the floor.

Tensile Strength:  Resistance to breaking. The amount of force required to break a membrane by stretching.

Tensiometer:  Device used to read the surface tension of a liquid or to reading the interfacial tension between two immiscible liquids.

Tent:  A fire retardant polyethylene enclosure that includes walls, ceiling and a floor as required to remove ACM, PACM or asbestos material.

Teratogen:   Substance that causes malformation or serious deviation from normal development of embryos and fetuses.

Terpenes:  A class volatile organic compounds frequently encountered indoors from such sources as air fresheners, cleansers, furniture polishes, and bathroom deodorants. Two odor-masking terpenes- citrus-like limonene and the evergreen-like a-pinene – are among the most common VOCs found indoors.

Terminal Reheat System:  A type of HVAC system that continuously supplies air at a constant level year round, with heating coils at the terminals allowing either cooling or heating at different zones.

Terminal Pressure:  Pressure drop across the unit at the time system is shut down or when the maximum allowable pressure drop is reached.

Terminal Velocity:  Steady velocity achieved by a falling particle when gravitational forces are balanced by viscous forces.

Termites: Insects that superficially resemble ants in size, general appearance, and habit of living in colonies; hence, they are frequently called “white ants.” Subterranean termites establish themselves in buildings not by being carried in with lumber, but by entering from ground nests after the building has been constructed. If unmolested, they eat the woodwork, leaving a shell of sound wood to conceal their activities, and damage may proceed so far as to cause collapse of parts of a structure before discovery. There are about 56 species of termites known in the United States but the two major ones, classified by the manner in which they attack wood, are ground inhabiting or subterranean termites (the most common) and dry wood termites, which are found almost exclusively along the extreme southern border and the Gulf of Mexico in the United States.

Termite Shield: A shield, usually of non-corrodible metal, placed in or on a foundation wall or other mass of masonry or around pipes to prevent passage of termites.

Terneplate: Sheet iron or steel coated with an alloy of lead and tin.

Terracotta: A ceramic material molded into masonry units.

Tertachloroethylene:  A probable carcinogen with a chloroform-like odor, emitted from dry-cleaned fabrics; also known as perchloroethylene (PERC). High exposures may result in a number of physiological effects, primarily to the nervous system, with symptoms including dizziness, headaches and vertigo.

Tertiary Treatment:  Wastewater treatment beyond primary and secondary treatment.  For example, chemical treatment, carbon filtration, etc.

Test Program:  A formalized schedule of tests, which specify the test sequence, the procedures to be employed, and the acceptance criteria.

Testing, Adjusting and Balancing:  The diagnostic and corrective procedures for HVAC controls and operating components to ensure provision of specified airflow rates and environmental conditions. Parameters tested include: supply, return, exhaust, and outdoor flow rates; control settings and operations; air temperatures; fan speeds and power consumption; and filter resistance. TAB is a recommended procedure following any modification to the HVAC system including new installation, cleaning, or adjustments of controls, as well as for certain IAQ investigations that suggest faulty or inadequate ventilation.

Testing and Certification:  In order to be assured your cleanroom meets prescribed standards, testing and certification of the room itself, as well as major components is recommended. HEPA and ULPA filters, laminar flow equipment, ionization equipment, safety cabinets and HVAC equipment, and others, are recommended for testing annually.

• As Built - A term used to describe a functioning cleanroom with no furniture, process equipment, or personnel. When inspected, it is considered ‘as built’. This level is usually tested in new rooms only and is very easy to pass.
• At Rest - A term used to describe a fully operational room with furniture, process and support equipment in place but not operating with personnel. When inspected, it is considered ‘at rest’. This is the most commonly tested condition and is also easy to pass because no particles are being generated within the room by personnel.
• Operational - When the cleanroom is fully furnished and staffed, it is considered operational. This is the most difficult inspection level to pass because it includes personnel, the dirtiest component of an operational cleanroom. People can shed hundreds of thousands of particulate per hour.

Testosterone: A white crystalline steroid hormone: produced primarily in the testes and responsible for the development and maintenance of male secondary sex characteristics.

Tetanus:  The disease called Tetanus occurs when a wound becomes infected with bacterial spores of Clostridium tetani. These spores grow and produce a very powerful toxin which affects the muscles by producing rigidity, and in severe cases convulsions. Treatment is difficult, and vaccination is the only way to provide safe, effective long-term protection against tetanus.

Textile: That which is or may be woven. Comes from the Latin “Texere,” which means to weave. Hence any kind of fabric.

Texture Paint: Paint which may be manipulated by brush, trowel or other to give various patterns.

Textured Yarn:  A yarn that has been geometrically altered to impart bulk, increase moisture absorption, add resiliency, etc.

Theophylline: A bronchodilator drug, taken orally, that widens the airways to the lung.

Theoretical Power:  The power required to compress a gas isothermally through a specified range of pressures.

Therm: The unit of energy equal to 100,000 Btus or 29.3 kilowatt-hours.

Thermidistat:  Highly sophisticated programmable thermostat that senses the outdoor temperature, indoor air temperature, and indoor relative humidity. A microprocessor communicates with the heating and cooling equipment to determine the most efficient way to achieve perfect comfort. When used with a variable speed blower motor, this cite can reduce humidity even when cooling isn’t necessary (as when the indoor temperature is 70 degrees but relative humidity is high, eg, when it’s raining).

Thermistor:  Is a heat sensitive resistor that changes resistance with a change in temperature.

Thermo-Anemometer: An instrument for measuring air velocity based on the removal of heat from a sensor as the air passes it.

Thermocirculation: Free convection from a warm zone (sunspace or Trombe-wall air space) to a cool zone through openings in a common wall.

Thermocirculation Vents: Openings in a common wall between cool and warm zones through which thermocirculation occurs. The vents are arranged in pairs, one of each pair near the floor and one near the ceiling.

Thermocouple: A bimetal-junction electric generator used to keep the safety valve of an automatic gas valve open.


Thermodynamic Air Purification:  A system of air purification using heat to destroy airborne microorganisms such as spores, fungus, bacteria, viruses and mold spores, incinerating them at temperatures around 400F (250ºC).

Thermodynamic Wet Bulb Temperature:  Also called the Adiabatic Saturation Temperature – is that temperature at which water, by evaporating into the air, can bring the air to saturation adiabatically at the same temperature. The wet bulb temperature measured with an appropriate psychrometer can approach the thermodynamic wet bulb temperature.

Thermodynamics: The science of heat.

Thermodynamics, Laws of:  Two laws upon which rest the classical theory of thermodynamics. These laws have been stated in many different, but equivalent ways. The First Law:; (1) When work is expanded in generating heat, the quantity of heat produced is proportional to the work expended; and, conversely when heat is employed in the performance of work, the quantity of heat which disappears is proportional to the work done; (2) If a system is caused to change from an initial state to a final state by adiabatic means only, the work done is the same for all adiabatic paths connecting the two states); (3) In any power cycle or refrigeration cycle, the net heat absorbed by the working substance is exactly equal to the net work done.  The Second Law: (1) It is impossible for a self-acting machine, unaided by an external agency, to convey heat from a body of lower temperature to one of higher temperature); (2) It is impossible to derive mechanical work from heat taken from a body unless there is available a body of lower temperature into which the residue not so used may be discharged); (3) It is impossible to construct an engine that, operating in a cycle, will produce no effect other than the extraction of heat from a reservoir and the performance of an equivalent amount of work.

Thermodynamics, First Law of:  The amount of work done on or by a system is equal to the amount of energy transferred to or from the system.

Thermodynamics, Second Law of:  Heat cannot, of itself, pass from a colder to a hotter body.

Thermodynamic Properties: Basic qualities used in defining the condition of a substance, such as temperature, pressure, volume, enthalpy, entropy.

Thermoluminescent Dosimeter (TLD):  Device used to measure external beta or gamma radiation levels, and which contains a material that, after exposure to beta or gamma radiation, emits light when processed and heated.

Thermopane Window: Compased of a double layer of glass positioned side by side with a thin strip of foam material bonding the two layers of window glass together to form the storm window design.

Thermoplastic Material: Solid material which is softened by increasing temperatures and hardened by decreasing temperatures.

Thermoply™: Exterior laminated sheathing nailed to the exterior side of the exterior walls. Normally ¼” thick, 4x8 or 4x10 sheets with an aluminumized surface.

Thermo-Regulation: The various physiological means by which the core temperature is regulated: vasoregulation, sweating and shivering.

Thermosiphon: The convective circulation of a fluid which occurs in a closed system where warm fluid uses and is replaced by a cooler fluid in the same system.

Thermosphere: The outermost layer of the Earth’s atmosphere extending from about 60 miles to several hundred miles. The temperature of this layer varies from many hundreds to thousands of degrees Celsius.

Thermostat:  A thermostat consists of a series of sensors and relays that monitor and control the functions of a heating and cooling system.

Thermostatic Expansion Valve:  A refrigerant metering device that maintains a constant evaporator temperature by monitoring suction vapor superheat; also called a thermal expansion valve.

Thimble: A connection between a cabinet exhaust outlet and the facility exhaust system through which room air may pass.

Thoracotomy:  Surgery through the chest wall.

Thorax: The muscular and bony structure of the chest.

Thread Count:  See mesh count.

Thread Diameter:  The cross-sectional measurement of an individual fabric thread/yarn or wire.

Thread Lifters:  A component of a carpet and rug tool that picks up loose threads and pet hair from the carpet surface so they can be removed by the vacuum cleaner's suction. Can be replaced when worn.

Threatened Species:  Under the Endangered Species Act, animal populations may be determined to be threatened when populations are less severely depleted than populations classed as endangered.

Three-Dimensional Shingles: See Laminated Shingles.

Three-Phase: In electrical contracting, a wiring system consisting of 4 wires and used in industrial and commercial applications. This system is suitable for installations requiring large motors. It consists of three hot wires and one ground wire. The voltage in each hot wire is out of phase with the others by 1/3 of a cycle, as if produced by 3 different generators.

Three-Stage Filter Separators: Liquid prefilter coalescer separators containing three kinds or types of replaceable elements.

Threshold: A strip of wood or metal with beveled edges used over the finish floor and the sill of exterior doors.

Threshold Limit Value:  Air concentration of chemical substances to which healthy workers can be exposed for 8-hour work days during a 40-hour work week without suffering an adverse effect.

Threshold Limit Values (TLV, TWA, PEL):  The highest allowable air concentration of a chemical to which nearly all workers may be repeatedly exposed for 8 hours a day, 40 hours per week, for a working lifetime, without negative health effects.

Threshold Limit Value – Ceiling (TLV-C):  An instantaneous exposure concentration never to be exceeded.

Threshold Limit Value – Short-Term Exposure Limit (TLV-STEL):  An exposure concentration that has been averaged over a 15-minute period, and that should not be exceeded; under certain conditions, exposure up to this level may occur, but no more than four times in a workday.

Threshold Limit Value – Time-Weighted Average (TLV-TWA):  An exposure concentration that has been averaged over an 8 hour workday and 40 hour workweek that should not be exceeded.; nearly all workers may be repeatedly exposed to these values for 8 hours a day, 40 hours per week, for a working lifetime, without negative health effects.

Threshold Odor:  See “Odor Threshold.”

Throttling Range:  Generally applied to pneumatic controls, where it is defined as the change in the controlled temperature which causes the branch line pressure to change from maximum to minimum or vice versa.

Throughput:  The amount of solution which will pass through a filter prior to plugging.

Throw:  The distance measured in feet that the air stream travels from the outlet to the point of terminal velocity. The throw is measured horizontally from the registers and ceiling diffusers, and vertically from perimeter diffusers.

Throw, Blow: Distance an air stream travels from an outlet to a position at which air motion reduces to a velocity of 50 FPM.

Thrust Balancing Device:  The part of a rotating element that counteracts any inherent thrust developed by the impellers.

Thru-Wall Flashing: Flashing extended completely through a masonry wall. Designed and applied in combination with counter-flashings, to prevent water which may enter the wall above from proceeding downward in the wall or into the roof deck or roofing system.

THW: Moisture and heat resistant thermoplastic conductor. It is flame retardant, moisture and heat resistant and can be used in dry or wet locations.

Thyroidectomy:  Surgical removal of the thyroid glands.

Tidal Volume:  The Tidal Volume in the lungs is the amount (volume) of air inhaled and exhaled with each normal breath.

Tidal Volume: The quantity of air inhaled and exhaled in one respiratory cycle during regular breathing.

Tie-In: In roofing, a term used to describe the joining of a new roof with the old.

Tight Building Syndrome (TBS):  A condition in which a building is very tightly sealed against infiltration, its ventilation is reduced for energy conservation, and airborne contaminants are sufficiently elevated to cause health effects in occupants; often used synonymously with sick building syndrome (SBS) or as a special case of SBS that can be traced to ventilation factors rather than to specific sources.

Tight Construction:  The elimination of gaps and holes in a building’s exterior through proper air sealing and ventilation. It reduces waste and makes a home more energy efficient.

Tight-fitting Facepiece:  A respirator inlet covering that forms a complete seal with the face; this type of inlet covering includes a quarter-facepiece that covers the user’s nose and mouth above the chin; a half-facepiece that covers the user’s nose and mouth under the chin and a full-facepiece that covers the user’s nose, eyes and mouth under the chin; refer to CSA Z94.4 for the definition.

Tilt: The angle of a plane relative to a horizontal plane.

Tilting Pad:  A type of journal bearing in centrifugal air compressors.

Tilt-Up Wall: Cast concrete units which are preformed which, when cured, are tilted to their vertical position and secured by mechanical fasteners to prior erected structural steel. May be pre-cast.

Timbers: Yard lumber 5 or more inches in least dimension. Includes beams, stringers, posts, caps, sills, girders, and purlins.

Time and Materials Contract: A contract which specifies a price for different elements of the work such as: cost per hour of labor, overhead, profit etc. Such a contract may not have a maximum price or may state a ‘price not to exceed.’

Time Sampling: Sampling by time of day; a wide time sample is necessary if the full experience of subjects is to be represented.

Time Schedule Order:  Set of specific actions a discharger shall take to correct or prevent violation of requirements.

Time-Weighted Average (TWA):  The average of the exposure concentration variations or excursions usually calculated over an 8-hour workday.

Tinner: Another name for the heating contractor.

Tinted Glass: Glass with colorants added to the basic glass batch that give the glass color as well as light and heat-reducing capabilities. The color extends throughout the thickness of the glass.

Tip Speed: Fan wheel velocity at a point corresponding to the outside diameter of the wheel blades; normally expressed in feet per minute (circumference times RPM).

Tip Up: The downspout extension that directs water (from the home’s gutter system) away from the home. They typically swing up when mowing the lawn, etc.

Tipping Pan Filter:  Process industry equipment which collects particulate from a liquid stream on a screen over a vacuum forming a dewatered cake and discharging the accumulation by tipping the collection screens.

Tissues:  Groups of similar cells joined to perform the same function.

Titanium Apatite Filter:  Odors collected on filter are broken down, bacteria and viruses are also absorbed and removed.

Titianium Oxide:  This is used by the Siesta Air Purifier to react with the Flash Streamer.  This produces a chemical reaction which kills germs and bacteria and neutralizes noxious gases and unpleasant odors. This chemical reaction prevents germs from breeding within the filter and from decomposing and producing odor.  Gases and odors are also prevented from leaking back into the atmosphere due to filter saturation.  The only emissions are CO2 and water vapor.

Title: Evidence (usually in the form of a certificate or deed) of a person's legal right to ownership of a property.

Title 24: A set of federal laws that mandates the construction industry to conserve energy.

Title III: A section of the 1990 amendments to the federal Clean Air Act that addresses the control of toxic air emissions.

Title V: A section of the 1990 amendments to the federal Clean Air Act that requires a federally enforceable operating permit for major sources of air pollution.

Title XVI: Term to be used interchangeably with those income groups known as SSI (Supplemental Security Income) recipients.

TJI or TJ: Manufactured structural building component resembling the letter “I.” Used as floor joists and rafters. I-joists include two key parts: flanges and webs. The flange may be made of laminated veneer lumber or dimensional lumber, usually formed into a 1½” width. The web is commonly made of plywood or oriented strand board (OSB).

TLVs: Threshold Limit Values (guidelines recommended by the American Conference of Governmental Industrial Hygienists).

TLV:  See Threshold Limit Values.

TLV-C:  See Threshold Limit Value – Ceiling.

TLV-TWA:  See Threshold Limit Value -Time Weighted Average.

Toe Bead: Sealant applied at the intersection of the outboard glazing stop and the bottom of the glazing channel. It must be sized to provide a seal to the edge of the glass.

Toe-Nailing: To drive a nail at a slant to the initial surface in order to permit it to penetrate into a second member.

Toluene:  Hydrocarbon derived mainly from petroleum but also from coal. Sources of TNT, lacquers, saccharin, and many other chemicals.

Ton:  Another unit used to measure the cooling capacity of an air conditioner. One ton of cooling is equal to 12,000 Btu’s/h.

Ton of Refrigeration:  The amount of heat required to melt a ton (2000 lb) of ice at 32'F, 288,000 Btu/24 h, 12,000 Btu/h, or 200 Btu/min.

Tongue and Groove: A type of flooring where the tongue of one board is joined to the groove of another board.

Tonnage:  The unit of measure used in air conditioning to describe the cooling capacity of a system. One ton of cooling is based on the amount of heat needed to melt one ton (2000 lbs.) of ice in a 24 hour period. One ton of cooling is equal to 12,000 Btu/hr.

Tooling: The operation of pressing in and striking a sealant in a joint to press the sealant against the sides of a joint and secure good adhesion; the finishing off of the surface of a sealant in a joint so that it is flush with the surface.

Top Chord: The upper or top member of a truss.

Top Mopping: The finished mopping of hot bitumen on a built-up roof.

Top Mount Faucet: See Centerset.

Top Plate: Top horizontal member of a frame wall.

Toplighting: Light which enters through the top part of interior space such as clerestories, light wells or skylights.

Topography: The configuration of a surface, especially the Earth’s surface, including its relief and the position of its natural and man-made features.

Torch Down Roof (Single Ply or Modified Bitumen): A newer roofing material mostly used on flat roofs. This material usually comes in rolls and is applied to the roof with an open flame or ‘torch.’

Torching: Applying direct flame to a membrane for the purpose of melting, heating or adhering.

Torque:  Torsional moment or couple. It usually refers to the driving couple of a machine or motor.

Torr:  A unit of pressure used with vacuum pumps, equal to 1mm of mercury and 133.32 Pascal’s.

Tortuous Path: Crooked, twisting or winding path which tends to trap or stop solid particles, commonly referenced in relationship to the flow pattern and makeup of a filter medium.

Tortuousity:  An continuous path that can be traced from a point on the upstream side of a filter to a point on the downstream side through a twisting pore pathway, traveled by the liquid or gas during filtration.

Total Ammonia:  The combined concentrations of the unionized (NH3) and ionized (NH4) forms of ammonia.

Total Containment: Means that no escape of aerosol is permitted. This is required for highly infectious or extremely dangerous agents.

Total Dissolved Solids:  Is the portion of the total solids in the sample that passes through the filter and is indicated by the increase in weight in the vessel after the filtrate has been dried at 356ºF.

Total Heat (Enthalpy):  Total heat is the sum of the sensible heat and latent heat in an exchange process. In many cases, the addition or subtraction of latent and sensible heat at terminal coils appears simultaneously. Total heat also is called enthalpy, both of which can be defined as the quantity of heat energy contained in that substance.

Total Heat Content:  The sum of sensible heat and latent heat.

Total Home Comfort System:  The ultimate solution to providing you with consistent, customized home comfort, despite the ever-changing weather.

Total Kjeldahl Nitrogen (TKN):  The sum of organic nitrogen and total ammonia nitrogen.

Total Lung Capacity: Total amount of air in the lungs when a person has breathed in as much as possible. This is one of the measurements obtained in a PFT.

Total Lung Capacity Test: A test that measures the amount of air in the lungs after a person has breathed in as much as possible.

Total Maximum Daily Load (TMDL):  A specific water quality attainment strategy for a water body and related impairment identified on the 303(d) list. The strategy defines specific measurable features that describe attainment of the relevant water quality standards. The strategy includes a description of the total allowable level of the pollutant(s) in question and allocation of allowable loads to individual sources or groups of sources of the pollutant(s) of concern.

Total Organic Gases (TOG): Gaseous organic compounds, including reactive organic gases and the relatively unreactive organic gases such as methane.

Total Organic Carbon (TOC):  Sum of the organic material present in a sample.

Total Organic Halides (TOX):  Sum of the organic halides present in a sample.

Total Package Input Power:  The total electrical power input to a compressor, including drive motor, cooling fan, motors, controls, etc.

Total Pressure: The algebraic sum of static and velocity pressures.

Total Solids / Suspended Solids:  The material residue left in the vessel after evaporation of a sample and its drying in an oven at 217-221ºF. The increase in weight over that of the empty vessel represents the total solids. Used in analyzing drinking water.

Total Suspended Particulate (TSP): Particles of solid or liquid matter – such as soot, dust, aerosols, fumes, and mist – up to approximately 30 microns in size.

Total Suspended Particulate Matter:   The mass of particles suspended in a unit volume of air when collected by a high-volume air sampler.

Total Volatile Organic Compounds (TVOCs):  A measure representing the sum of all volatile organic compounds present in the air to provide an approximate indication of pollutant levels. Indoor air typically contains hundreds of different VOC’s in very low concentrations, some of which can have additive effects. Since TVOC measures a variety of chemicals, researchers convert milligrams per cubic meter to parts per million using the molecular weight of a common compound, such as toluene.
Toxic:   Of, affected by, or caused by a toxin; to cause a poisonous reaction.

Toxic Air Contaminant (TAC): An air pollutant, identified in regulation by the ARB, which may cause or contribute to an increase in deaths or in serious illness, or which may pose a present or potential hazard to human health. TACs are considered under a different regulatory process (California Health and Safety Code section 39650 et seq.) than pollutants subject to CAAQSs. Health effects to TACs may occur at extremely low levels, and it is typically difficult to identify levels of exposure which do not produce adverse health effects.

Toxic Best Available Control Technology (T-BACT): The most effective emission limitation or control technique which (1.) has been achieved in practice for such permit unit category or class of source; or (2.) is any other emissions limitation or control technique, including process and equipment changes of basic and control equipment, found by the Executive Officer of the California Air Resources Board or Air Pollution Control Officer of the local districts to be technologically feasible for such class or category of sources, or for a specific source.

Toxic Hot Spots:  Waters that have toxic pollution problems even after industries have installed cleanup technologies required by the Clean Water Act. EPA put out a national list in June 1989 on such toxic waterways.

Toxic Pits Cleanup Act (TPCA):  Prevents drinking water supply contamination from and improper storage treatment, and disposal of liquid hazardous wastes in surface impoundments.

Toxic Pollutant:  Those pollutants or combinations of pollutants including disease-causing agents, which after discharge and upon exposure, ingestion, inhalation or assimilation into any organism, either directly from the environment or indirectly by ingestion through food chains, will, on the basis of information available, cause death, disease, behavioral abnormalities, cancer, genetic mutations, physiological malfunctions or physical deformations, in such organism or their offspring.

Toxic Release Inventory (TRI): Database of toxic releases in the U. S. compiled from SARA Title III Section 313 reports.

Toxic Substance:  A substance that either directly poisons living things or alters their environment so they die.

Toxic Substances Control Act (TSCA):  A federal law of 1976 to regulate chemical substances or mixtures that may present an unreasonable risk of injury to health or the environment.

Toxic Substances Monitoring Program (TSM):  Designed to detect the presence and concentration of toxic pollutants in fish and other aquatic organisms in selected California streams and lakes.

Toxicant:  A substance that can cause tissue damage or otherwise affect organs or systems in the body.

Toxicity:  Ability to harm human health or environment, such as injury, death or cancer. One of the criteria used to determine whether a waste is a hazardous waste (the “Toxicity Characteristic”).

Toxicology:  The study of the nature, effects and detection of poisons in living organisms. The basic assumption of toxicology is that there is a relationship among the dose (amount), the concentration at the affected site, and the resulting effects.

Toxigenic:  A substance or biological entity that has the property itself or can produce one or more compounds that have the property to harm humans or other animals.

TP: Total pressure. The sum of velocity pressure plus static pressure.

TPI: Twist per Inch.

TPY: Tons per Year.

Trace-Tek:  A brand name water detection system commonly used in underfloor areas of data centers. Employs a woven two-conductor cable which is routed around the floor in a serpentine pattern.

Tracer Gases: Compounds, such as sulfur hexaflouride, which are used to identify suspected pollutant pathways and to quantify ventilation rates. Trace gases may be detected qualitatively by their odor or quantitatively by air monitoring equipment.

Trachea:  A part of the respiratory system between the larynx and the bronchi; also called the windpipe.

Tracheobronchial:  Having to do with the region of the respiratory system that includes the trachea and the bronchi.

Tracheotomy: A surgical opening made when necessary in the main airway, the trachea.

Traditional Upright:  Traditional uprights are known as such because many of the early vacuum cleaners developed used a design in which unfiltered air passed through the fan and was then deposited into the dust bag. For this reason, these types of vacuum cleaners are also known as “Direct Air” or “Dirty Air” vacuum cleaners. This design often results in broken fans and other motor damage. Use of attachments in vacuum cleaners using this design is often awkward.

Train:  A set of components arranged in series.

Tramp Oil:  Free oil contained in emulsion type machine tool coolants. May be from machine leakage and from breakdown of the emulsifying agents in the cutting oil.

TRANE FreshEffects™ (also Energy Recovery Ventilator or FreshEffects™):  Energy efficient system to exchange stale indoor air for an equal amount of fresher outdoor air.

Transboundary Pollutants: Air pollution that travels from one jurisdiction to another, often crossing state or international boundaries. Also applies to water pollution.

Transducer:  A substance or device, that converts input energy of one form into output energy of another.

Transfer Air:   The movement of indoor air from one space to another.

Transfer Efficiency: For coatings, a measure of the percent of the total amount of coating used which is transferred to a unit surface by a spray gun or other device.

Transformer: A double coil of wire that increases or decreases voltage from a primary circuit to a secondary circuit.

Transient:  Staying only for a short time.

Transit: A surveyor’s instrument used by builders to establish points and elevations both vertically and horizontally. It can be used to line up stakes or to plumb walls or to measure the angle of elevation from a horizontal plane.

Transition: A change in the cross-sectional area or shape of a duct or hood.

Transmission (light): Passage of radiation through a medium without change of frequency of its monochromatic components.

Transmission: The movement or transfer of electric energy over an interconnected group of lines and associated equipment between points of supply and points at which it is transformed for delivery to consumers, or is delivered to other electric systems. Transmission is considered to end when the energy is transformed for distribution to the consumer.  In thermodynamics, a general term for heat travel; properly, heat transferred per unit of time.

Transmission System (Electric): An interconnected group of electric transmission lines and associated equipment for moving or transferring electric energy in bulk between points of supply and points at which it is transformed for delivery over the distribution system lines to consumers, or is delivered to other electric systems.

Transmittance, Radiant: The ratio of the radiant energy transmitted by parallel sided plane sheet of a given material to the radiant energy incident on the outside surface of that material: the value depends on the angle of incidence and wavelength. For any wavelength and angle of incidence, absorptance + reflectance + transmittance = 1.

Transmitter (Garage Door): The small push-button device that causes the garage door to open or close.

Transom:  A manually controlled opening above a door used to allow air to exit a room.

Transport Velocity:  See Minimum Transport Velocity.

Transportation Control Measure (TCM): Any control measure to reduce vehicle trips, vehicle use, vehicle miles traveled, vehicle idling, or traffic congestion for the purpose of reducing motor vehicle emissions. TCMs can include encouraging the use of carpools and mass transit.

Transuranic Waste (TRU):  Material contaminated with alpha-emitting transuranium nuclides, which have an atomic number greater than 92 (e.g., plutonium-239), half-lives longer than 20 years, and are present in concentrations greater than 100 nCi/g of waste.

Transverse Sampling: A method of choosing a population sample for a survey by taking one or a few comfort votes from a large number of subjects (cf longitudinal sampling).

Trap: A plumbing fitting that holds water to prevent air, gas, and vermin from backing up into a fixture.

Traverse: A method of sampling points in a duct where pressure readings will be taken to determine velocity. A traverse divides the duct into equal, evenly distributed areas that are each tested, compensating for errors caused by uneven gas flow in the duct.

Tread: The horizontal board in a stairway on which the foot is placed.

Treated Lumber: A wood product which has been impregnated with chemicals to reduce damage from wood rot or insects. Often used for the portions of a structure which is likely to be in ongoing contact with soil and water. Wood may also be treated with a fire retardant.

Treatment:  The process of removing all or a part of one or more chemical components, particulate components, or radionuclides from an off-gas stream.

Tree-Free Paper:  Paper made with alternative resources such as kenaf and hemp, without using virgin tree pulp.

Tremie: A tube with removable sections and a funnel at the top used in concrete application. The bottom is kept beneath the surface of the concrete and raised as the form is filled and is used to pour concrete underwater.

Triac Speed Controller: Solid-state device which can be adjusted to vary the AC voltage at the output through a range from essentially zero up to full line voltage.

Triboelectric Series (Potential/Charge):  An inherent natural or induced positive or negative polarity charge that many materials possess. Fibers or a filtration medium with a triboelectric potential will capture charged and potentially neutral particles, assuming both positive and negative properties on the surface of the material. Triboelectric properties only work in air filtration assuming relative humidity below 90 %.

Triboelectricity:  The charge of electricity that is generated by friction such as rubbing.

Tributary:  Connected to another body of water.

Trichloroethylene:  A stable, low boiling-point colorless liquid, toxic if inhaled. Used as a solvent or metal degreasing agent, and in other industrial applications.

Tricot:  A type of knitted fabric.

Triforce:  Panasonic three-stage design.  Two fan design motor with an additional air diffuser to create additional airflow.  Results in more airflow with the same amount of amperage.

Trigger: Anything that causes asthma symptoms to worsen in a given person. Different things are triggers for different people. Common triggers include exercise, cigarette smoke, pollen, dust, cold air, and aspirin/NSAIDs. Upper respiratory infections are perhaps the most common trigger for asthma symptoms.

Trim: Decorative wood that covers cracks around window and door openings and at the corners where walls meet floors and ceilings. Sometimes called molding.

Trim (Exterior): The finish materials on the exterior of a building, such as moldings applied around openings (window trim, door trim), siding, windows, exterior doors, attic vents, crawl space vents, shutters, etc. Also, the physical work of installing these materials.

Trim (Interior): The finish materials in a building, such as moldings applied around openings (window trim, door trim) or at the floor and ceiling of rooms (baseboard, cornice, and other moldings). Also, the physical work of installing interior doors and interior woodwork, to include all handrails, guardrails, stairway balustrades, mantles, light boxes, base, door casings, cabinets, countertops, shelves, window sills and aprons, etc.

Trim (Plumbing, Heating, Electrical): The work that the “mechanical” contractors perform to finish their respective aspects of work when the home is nearing completion and occupancy.

Trim Edge:  A removable plastic strip attached to the four edges of access floor panels. The trim edge provides a decorative edge and compliance between adjacent floor panels.

Trim Kit: Refers to the outside decorative parts that conceal a faucet rough-in.

Trimmer: A beam or joist to which a header is nailed in framing for a chimney, stairway, or other opening.

Triple Bottom Line Reporting:  New form of corporate disclosure which integrates financial, environmental and social reporting.

Triple-Glazed Window: The most energy efficient window. Gases are sealed between three panes of glass and Low E coatings are applied on two of the panes. This can bring the energy efficiency up to a value of R10 at the center point of the glass.

Tritium:  Radioactive isotope of hydrogen, containing one proton and two neutrons in its nucleus, which decays at a half-life of 12.3 years by emitting a low-energy beta particle.

Trombe Wall: A thermal storage wall of masonry placed between the solar aperture and the heated space. Heat is transferred into the space by conduction through the masonry and, if vents are provided, by natural convection.

Troposphere: The layer of the atmosphere closest to the earth's surface.

True Dendity:  Mass of a particle divided by its volume, pores etc. being excluded from the volume calculation.

True HEPA:  See “HEPA.”

True Medical Grade HEPA:  An Austin Air trade name for a certified HEPA filter. See “HEPA.”

TrueSense Dirty Filter Detection:  TrueSense™ dirty filter detection reminds you when it’s time to change your media filter.

Trunk Compressor:  A compressor belonging to the group of displacement reciprocating compressors.

Trunnion:  A device for mounting cylinders.

Truss: A lightweight, rigid framework designed to be stronger than a solid beam of the same weight.

TSCA (Toxic Substances Control Act.): Administered by the EPA, was passed by Congress to protect human health and the environment by requiring testing and necessary use restrictions to regulate the commerce of certain chemical substances.

TSP:   Total suspended particulate concentration.

TST: Tuberculin Skin Test. Refers to administration of the Mantoux TB skin test and replaces the term ‘PPD.’

Tubbeaxial Fan: Axial fan without guide vanes.

Tube and Knob Wiring: A common form of electrical wiring used before World War II. When in good condition it may still be functional for low amperage use such as smaller light fixture.

Tub Trap: A curved, “U” shaped section of a bath tub drain pipe that holds a water seal to prevent sewer gasses from entering the home through tubs water drain.

Tuck-Pointing: The re-grouting of defective mortar joints in a masonry or brick wall.

Tugger:  An air operated device for hoisting or pulling. Similar to a slusher or winch.

Tundish:  A receptacle, open to atmosphere, that is used to used to collect condensate. For example, two or three drain pipes from various filters may be discharging into a funnel. In this case the funnel is a tundish.

Turbidimeter: An instrument for measurement of turbidity, in which a standard suspension usually is used for reference.

Turbidity:  Suspended and colloidal matter (e.g. clay, silt, organic and inorganic matter, etc.) in water.

Turbine: A machine for generating rotary mechanical power from the energy of a stream of fluid (such as water, steam, or hot gas). Turbines convert the kinetic energy of fluids to mechanical energy through the principles of impulse and reaction, or a mixture of the two.

Turbine Nozzle:  Sometimes referred to as a Turbo Brush or Turbo Nozzle, a Turbine Nozzle is a cleaning nozzle used with canister vacuum cleaners where a revolving brush is powered by the airflow of the canister’s suction motor. Turbine Nozzles are not as powerful or effective as electrically powered power nozzles but do provide excellent cleaning in certain environments, carpet types and soiling conditions. The air used to drive the Turbine Nozzle is removed from the primary airflow, therefore decreasing the suction power of the vacuum system to some degree.

Turbine Nozzle Handheld:  This is a smaller version of an air driven Turbine Nozzle that is used to clean stairs, corners, vehicles and durable upholstery. It is excellent for removing pet hair and other difficult soils. See “Turbine Nozzle.”

Turbobrush:  This is Miele’s trade name for their air powered revolving brush cleaning nozzle. See “Turbine Nozzle.”

Turbobrush Handheld:  This is Miele’s trade name for their handheld air powered revolving brush cleaning nozzle. See “Turbine Nozzle Handheld.”

Turboflo Vacuum Turbine:  A trade name for a by-pass cooled vacuum motor used in Numatic wet/dry vacuum cleaners.

Turbulent Flow:  Flow regime in which the flow characteristics are governed mainly by the inertia of the fluid. Turbulent flow in ducts is associated with high Reynolds Number (Re). It also gives rise to high drag.

Turning Vanes: Baffles put in a duct to straighten out the air flow.

Turnkey: A term used when the subcontractor provides all materials (and labor) for a job.

Turpentine: A volatile oil used as a thinner in paints and as a solvent in varnishes. Chemically, it is a mixture of terpenes.

TVOCs:   Total volatile organic compounds.

TW: A moisture-resistant thermoplastic conductor that can be used in dry or wet locations, has no outer covering and is not heat-resistant.

TWA:  See Threshold Limit Value –Time Weighted Average.

Twill Weave:  Formed by passing the warp or weft fiber over two or more fibers in the opposite direction.

Twin Energy:  Sharp two-stage or two-fan motor.

Twist:  Turns imparted to a length of yarn. Usually expressed in tpi
(turns per inch).

Two-Part Sealant: A product composed of a base and curing agent or accelerator, necessarily packaged in two separate containers which are uniformly mixed just prior to use.

Two-Position: Essentially, on/off operation, or open/closed.
Two-Stage Compressor:  Compressor composed of a high and low stage to increase efficiency and comfort while reducing operation noise.

Two-Stage Heating / Two-Stage Cooling:  Two-stage heating and cooling is considered to be more efficient, because it operates at low speed most of the time. However, on days when more heating or air conditioning is required, it switches to the next stage for maximum comfort.

Two Step Control:  Load/unload control system that tries to maximizes compressor efficiency by matching air delivery and air demand. Compressor is operated at full load or idle.

TX Valve:  A precision device used to regulate the rate of refrigerant flow into the evaporator to exactly match the rate of refrigerant evaporation.

TXV Valve:  A thermal expansion valve.

Tympanometry:  Pronunciation (tim′pă-nom′ĕ-trē).  A technique that measures immittance of the middle ear at various levels of air pressure; helpful in the diagnosis of middle ear effusion, eustachian tube function, and otitis media.

Type I:  A safety can with a single spout.

Type II:  A safety can with two openings; one for pouring and one for filling.

Type I Hypersensitivity (anaphylactic reactions):  An immediate, usually localized response to allergens such as fungi, pollen, dust mites, or animal dander; examples of this type of disorder include insect stings, asthma, food allergies, drug reactions, and hives;  type of antibodies involved: IgE.

Type II Hypersensitivity (cytotoxic reactions):  A delayed response (usually within hours or days) involving reactions against antigens located on target cells which are then destroyed; examples of this type of disorder include blood transfusions reactions and hemolytic disease of newborns (involving Rh factors); type of antibodies involved: IgG, IgM.

Type III Hypersensitivity (immune-complex reactions):  A delayed response (usually within hours or days) involving insoluble antigen-antibody complexes which cause tissue necrosis (death) and acute inflammation; examples of this type of disorder include Farmer’s Lung (caused by fungi and other microorganisms), serum sickness, and malaria; type of antibodies involved IgG, IgM.

Type IV Hypersensitivity (cell-mediated response):  A delayed response to microorganisms, tissue transplants, or chemicals that cause cellular inflammation; examples of this type of disorder include contact dermatitis, and Tuberculosis reactions (Mantoux test); type of antibodies involved: none.

Type C Respirator:  An airline respirator, for entry into and escape from atmospheres not immediately dangerous to life or health, which consists of a source of respirable breathing air, a hose, a detachable coupling, a control valve, orifice, a demand valve or pressure demand valve, and arrangement for attaching the hose to the wearer and a facepiece, hood, or helmet.

Type CE Respirator:  A Type C supplied-air respirator equipped with additional devices designed to protect the wearer’s head and neck against impact and abrasion from rebounding abrasive material, and with shielding material such as plastic, glass, woven wire, sheet metal, or other suitable material to protect the window(s) of facepieces, hoods, and helmets which do not unduly interfere with the wearer’s vision and permit easy access to the external surface of such window(s) for cleaning.

Type N Particulate Filter:  NIOSH classification for particulate filters effective against particulate aerosols free of oil; these filters may have time restrictions; refer to CSA Z94.4 and NIOSH for complete details.

Type P Particulate Filter:  NIOSH classification for particulate filters effective against all particulate aerosols; refer to CSA Z94.4 and NIOSH for complete details.

Type R Particulate Filter:  NIOSH classification for particulate filters effective against all particulate aerosols; these filters may have time restrictions; refer to CSA Z94.4 and NIOSH for complete details

Tyvek®:  A disposable non-woven fabric made by spun bonding millions of tiny polyethylene fibers.  This process yields a lightweight fabric that is tough with outstanding tensile and tear strength.  Manufactured by DuPont company and used for disposable clothing applications.