A round galvanized steel duct connecting to a typical diffuser Ducts are used in heating, ventilation, and air conditioning (HVAC) to deliver and remove air. These needed airflows include, for example, supply air, return air, and exhaust air.[1] Ducts also deliver, most commonly as part of the supply air, ventilation air. As such, air ducts are one method of ensuring acceptable indoor air quality as well as thermal comfort. Image File history File links Central_ventilation_tube2. ...
Image File history File links Central_ventilation_tube2. ...
A diffuser is the mechanical device that is designed to control the characteristics of a fluid at the entrance to a thermodynamic open system. ...
Image File history File links Size of this preview: 800 × 581 pixelsFull resolution (4875 × 3540 pixel, file size: 1. ...
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International time/temperature curves used to run commercial furnaces for testing the Fire-resistance rating of passive fire protection systems, such as firestops, fire doors, wall and floor assemblies, etc. ...
Sheets of stainless steel cover the Chrysler Building Thin sheets of gold leaf Sheet metal is simply metal formed into thin and flat pieces. ...
For other uses, see Copper (disambiguation). ...
PIPE can refer to PIPE (explosive) PIPE Networks Private Investment in Public Equity (PIPE) Physical Interface for PCI Express (PIPE) For other meanings, see also pipe. ...
Perimeter slab edge building joint with incomplete firestop, between concrete floor and precast concrete facade. ...
This article is about the construction material. ...
Firestop after fire exposure during fire test in Tulsa, Oklahoma. ...
Caulking - Wikipedia /**/ @import /w/skins-1. ...
Mineral wool, means fibres made from minerals or metal oxides, be they synthetic or natural. ...
HVAC may also stand for High-voltage alternating current HVAC systems use ventilation air ducts installed throughout a building that supply conditioned air to a room through rectangular or round outlet vents, called diffusers; and ducts that remove air from return-air grilles Fire-resistance rated mechanical shaft with HVAC...
HVAC may also stand for High-voltage alternating current HVAC systems use ventilation air ducts installed throughout a building that supply conditioned air to a room through rectangular or round outlet vents, called diffusers; and ducts that remove air from return-air grilles Fire-resistance rated mechanical shaft with HVAC...
Return inlet (left)Supply outlet (right). ...
Indoor Air Quality (IAQ) deals with the content of interior air that could affect health and comfort of building occupants. ...
Human thermal comfort is the state of mind that expresses satisfaction with the surrounding environment, according to ASHRAE Standard 55. ...
A duct system is often called ductwork. Planning ('laying out'), sizing, optimizing, detailing, and finding the pressure losses through a duct system is called duct design.[2]
Duct materials
Like modern steel food cans, at one time air ducts were often made of tin, like 'tin cans' were made for food. Tin is more corrosion resistant than plain steel, but is also more expensive. With improvements in mild steel production, and its galvanization to resist rust, steel 'sheet metal' has replaced tin in ducts as well as food cans. However, the term tin-knocker is still used in practice to describe sheet metal duct installers. For other uses, see Rust (disambiguation). ...
Today, if we consider all the materials which allow us to construct ducts in rectangular, round, or oval cross-sectional shapes, we will find that the four main ones are:
Galvanized steel
Ducts are still most often made of galvanized steel. Various fittings allow transitioning between the various shapes and sizes. A "tee" connection, for example, is where the air flow can be divided into two or more downstream branches. Many factory-made shapes and sizes are available but galvanized steel can easily be cut and bent to form additional shapes when required. Steel ducts are commonly wrapped or lined with fiberglass thermal insulation, both to reduce heat loss or gain through the duct walls and water vapor from condensing on the exterior of the duct when the duct is carrying cooled air. Insulation, particularly duct liner, also reduces duct-borne noise. Both types of insulation reduce 'breakout' noise through the ducts' sidewalls. Sheet metal forming refers to the various processes used to convert cold rolled metal sheet into finished parts such as aluminium cans and automobile body panels. ...
Bundle of fiberglass Fiberglass (also called fibreglass and glass fibre) is material made from extremely fine fibers of glass. ...
Thermal insulation on the Huygens probe The term thermal insulation can refer to materials used to reduce the rate of heat transfer, or the methods and processes used to reduce heat transfer. ...
For other uses, see Condensation (disambiguation). ...
Polyurethane duct board (Preinsulated aluminum ducts)
While as mentioned above, galvanized steel is still very common, always more rectangular ducts are being manufactured from “duct board”, thanks to the fact that custom or special shapes and sizes of ducts can easily be shop or field fabricated. In addition to the fact that ducts made with “duct board” do not need any further insulation. Among the various types of rigid polyurethane foam panels available, a new water formulated panel stands out. In this particular panel, the foaming process is obtained through the use of water instead of the CFC, HCFC, HFC and HC gasses. The foam panels are then coated with aluminum sheets on either side, with thicknesses that can vary from 50 micrometres for indoor use to 200 micrometres for external use in order to guarantee the high mechanical characteristics of the duct. The ducts construction starts with the plotting of the single pieces on the panel. The pieces are then cut from the panel (with a 45° cut as explained below), bent if necessary in order to obtain the different fittings, and finally closed through an operation of gluing, pressing and taping. Having obtained the various duct sections, they can easily be installed by using an invisible aluminum flange system. In geometry, a rectangle is a defined as a quadrilateral polygon in which all four angles are right angles. ...
A polyurethane is any polymer consisting of a chain of organic units joined by urethane links. ...
CFC, cfc, or Cfc may stand for: Chlorofluorocarbon : a class of chemical compounds known to inflict great damage to the ozone layer. ...
Aluminum is a soft and lightweight metal with a dull silvery appearance, due to a thin layer of oxidation that forms quickly when it is exposed to air. ...
A micrometre (American spelling: micrometer), symbol µm, is an SI unit of length. ...
For the vacuum component, see Vacuum flange. ...
Fiberglass duct board (Preinsulated non metallic ductwork)
Also the fiberglass panels provide built-in thermal insulation and the interior surface absorbs sound, helping to provide quiet operation of the HVAC system. The duct board is formed by sliding a specially-designed knife along the board using a straightedge as a guide; the knife automatically trims out a "valley" with 45° sides; the valley does not quite penetrate the entire depth of the duct board, providing a thin section that acts as a hinge. The duct board can then be folded along the valleys to produce 90° folds, making the rectangular duct shape in the fabricator's desired size. The duct is then closed with staples and special aluminum or similar 'metal-backed' tape. Commonly available duct tape should not be used on air ducts, metal, fiberglass, or otherwise, that are intended for long-term use; the adhesive on so called 'duct tape' dries and releases with time. This article is about audible acoustic waves. ...
This article is about the tool. ...
A hinge is a type of bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. ...
A roll of silver duct tape. ...
Flexible tubing
Flexible ducts, known as flex, have a variety of configurations, but for HVAC applications, they are typically flexible plastic over a metal wire coil to make round, flexible duct. Most often a layer of fiberglass insulation covers the duct, and then a thin plastic layer protects the insulation. Flexible duct is very convenient for attaching supply air outlets to the rigid ductwork. However, the pressure loss through flex is higher than for most other types of ducts. As such, designers and installers attempt to keep their installed lengths (runs) short, e.g., less than 15 feet or so, and to minimize turns. Kinks in flex must be avoided. Flexible duct is normally not used on the negative pressure portions of HVAC duct systems.
Duct system components Besides the ducts themselves, complete ducting systems contain many other components.
Vibration isolators A duct system often begins at an air handler. The blowers in the air handlers can create substantial vibration and the large area of the duct system would transmit this noise and vibration to the inhabitants of the building. To avoid this, vibration isolators (flexible sections) are normally inserted into the duct immediately before and after the air handler. The rubberized canvas-like material of these sections allow the air handler to vibrate without transmitting much vibration to the attached ducts. An air handling unit; air flow is from the right to left in this case. ...
For other uses, see Fan. ...
Look up vibration in Wiktionary, the free dictionary. ...
This article is about noise as in sound. ...
Take-offs Downstream of the air handler, the supply air trunk duct will commonly fork, providing air to many individual air outlets such as diffusers, grilles, and registers. When the system is designed with a main duct branching into many subsidiary branch ducts, fittings called take-offs allow a small portion of the flow in the main duct to be diverted into each branch duct. Take-offs may be fitted into round or rectangular openings cut into the wall of the main duct. The take-off commonly has many small metal tabs that are then bent to retain the take-off on the main duct; round versions are called spin-in fittings. Other take-off designs use a snap-in attachment method, sometimes coupled with an adhesive foam gasket to provide improved sealing. The outlet of the take-off then connects to the rectangular, oval, or round branch duct. A diffuser is the mechanical device that is designed to control the characteristics of a fluid at the entrance to a thermodynamic open system. ...
Stacks, boots, and heads Ducts, especially in homes, must often allow air to travel vertically within relatively thin walls. These vertical ducts are called stacks and are formed with either very wide and relatively thin rectangular sections or oval sections. At the bottom of the stack, a stack boot provides a transition from an ordinary large round or rectangular duct to the thin wall-mounted duct. At the top, a stack head can provide a transition back to ordinary ducting while a register head allows the transition to a wall-mounted air register.
Dampers Ducting systems must often provide a method of adjusting the volume of air flow to various parts of the system. Balancing, flow-control, and fire/smoke dampers provide this function. Besides the regulation provided at the registers or diffusers that spread air into individual rooms, dampers can be fitted within the ducts themselves. These dampers may be manual or automatic. Zone dampers provide automatic control in simple systems while VAVs allow control in sophisticated systems. In a duct or chimney, a damper is a valve or plate that stops or regulates the flow of air. ...
A zone damper is a specific type of damper used to control the flow of air in an HVAC heating or cooling system. ...
A variable air volume (VAV) device is a computer-controlled zone damper used in HVAC systems to vary the flow of air through ductwork. ...
Terminal units While single-zone constant air volume systems typically don't have them, other types of air distribution systems often have terminal units in the branch ducts. Usually there is one terminal unit per thermal zone. Some types of terminal units are VAV 'boxes' of either single or dual duct, fan-powered mixing boxes of either parallel or series arrangement, and induction terminal units. Terminal units may also include either, or both, a heating or cooling coil. Constant Air Volume (CAV) is a type of heating, ventilating, and air-conditioning (HVAC) system. ...
Air terminals Air terminals are the supply air outlets and return or exhaust air inlets. For supply, diffusers are most common, but grilles, and for very small HVAC systems such as in residences, registers are also used widely. Return or exhaust grilles are used primarily for appearance reasons, but some also incorporate an air filter and are known as filter returns.[3] A diffuser is the mechanical device that is designed to control the characteristics of a fluid at the entrance to a thermodynamic open system. ...
BMWs distinctive kidney-shaped grille on an E34 M5 Audis single frame grille, here on a second generation TT Grille is also the name of a German self-propelled artillery vehicle. ...
See also Characterizing how air is introduced to, flows through, and is removed from spaces is called room air distribution. ...
Natural ventilation is the process of supplying and removing air through an indoor space by natural means. ...
For other uses, see Fan. ...
Pressurisation ductwork is a fire protection system subject to stringent bounding. ...
Smoke Exhaust Ductwork is typically protected via passive fire protection means, subject to fire testing and stringent bounding, and is used to remove smoke from buildings, ships or offshore structures to enable emergency evacuation as well as improved firefighting. ...
The Sheet Metal and Air Conditioning Contractors National Association (SMACNA; pronounced Smack-Nah) is an international association of union HVAC contractors. ...
The Association of Chartered Certified Accountants (ACCA) is a British chartered accountancy body with a global presence that offers the Chartered Certified Accountant (Designatory letters ACCA or FCCA) qualification worldwide. ...
The Air Movement and Control Association International, Inc. ...
The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) is an international voluntary organization for people involved in heating, ventilation, air conditioning, or refrigeration (HVAC&R). ...
References - ^ The Fundamentals volume of the ASHRAE Handbook, ASHRAE, Inc., Atlanta, GA, USA, 2005
- ^ HVAC Systems -- Duct Design, 3rd Ed., SMACNA, 1990
- ^ Designer's Guide to Ceiling-Based Room Air Diffusion, Rock and Zhu, ASHRAE, Inc., Atlanta, GA, USA, 2002
The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) is an international voluntary organization for people involved in heating, ventilation, air conditioning, or refrigeration (HVAC&R). ...
The Sheet Metal and Air Conditioning Contractors National Association (SMACNA; pronounced Smack-Nah) is an international association of union HVAC contractors. ...
The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) is an international voluntary organization for people involved in heating, ventilation, air conditioning, or refrigeration (HVAC&R). ...
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