3 Terms & Definitions

For the purpose of this guide, the following terms and definitions apply addressable fire detection system a system in which signals from detectors, manual call points or any other device which are individually identified at the control and indicating equipment approving authority organisation, officer or individual responsible for approving smoke and heat control systems, equipment or procedures backlayering the tendency of smoke to flow against the general direction of airflow due to thermal energy or air currents created by the action of the jet fans ceiling jet any layered flow of ceiling level gases away from the point of impingement, driven by the smoke layer’s buoyancy computational fluid dynamics model (CFD model) computer simulation model where the fundamental equations of energy, mass and momentum transfer are solved using numerical methods cross-flow ventilation ventilation system based on creating an airflow throughout a space by drawing air from outside, passing the air through and across the space and discharging to outside. design fire hypothetical fire having characteristics which are sufficiently severe for it to serve as the basis of the design of the smoke and heat control system dispersal removal of a smoke hazard by dilution with clean air environmental controls controls used for the purpose of controlling the environmental and air conditioning systems serving the building in which a smoke control system is installed. exhaust ventilation system combination of exhaust ventilators, fans, ducts, power supplies and controls used to remove smoky gases from a space. extract point A point of extract from a ventilated space. fire compartment enclosed space comprising one or more separate spaces bounded by elements of a structure having a specified fire resistance and intended to prevent the spread of fire (in either direction) for a given period of time (BS7346: Part 4)

fire engineered solution fire safety strategy and design based upon calculations tailored to the circumstances of a specific building fire load sum of the heat energy which could be released by complete combustion of the combustible materials in a space including combustible materials in the space. fire resistance ability of an item to fulfil for a stated period of time the required fire stability and/or integrity and/or thermal insulation, and/or other expected duty specified in a standard fire resistance test (BS4422: 2005) fire service override switch manually operated switch to enable fire fighters to initiate or terminate the operation of a fire safety system or other device fixing Device used to secure plant or equipment to the structure of a building frequency inverter Electronic device used to control the speed of fans by controlling the frequency of the electrical supply to the fan motor(s) impulse fan See jet fan jet fan A fan designed to transfer momentum into the air, for example as part of an impulse ventilation system impulse ventilation system A system using jet fans to control the flow of air through a space, for example within a car park or loading bay integrity The ability of a separating element to contain a fire to a specified criteria for collapse, freedom from holes, cracks and fissures and sustained flaming on the exposed face Isolating protective device A means of isolating electrical power from the smoke control system or a component within it, possibly for maintenance purposes means of escape Structural means whereby, in the event of a fire, a safe route is provided for persons to travel from any point in the building to a place of safety mechanical cross ventilation A system of smoke control where a mechanical means are used to sweep air horizontally through a space to remove smoke multi-criteria fire detection fire detection system monitoring more two or more fire phenomena

natural cross ventilation system of smoke control where openings are used to allow wind pressure and/or buoyancy to induce a flow of air through a space to remove smoke override control control included in an automatically operating smoke and heat control system to allow manual operation or manual shut down of all or part of that system primary power source the main source of power supply serving the smoke control system rapid rate of rise heat detection automatic fire detection system which initiates an alarm when the rate of change of the measured temperature with time exceeds a predetermined value for a predetermined time replacement air clean air entering a building to replace smoke being removed by the smoke and heat control system secondary power source an electrical supply completely separate to the primary source and which provide the power to the smoke control system in the event of failure of the primary power source smoke clearance system smoke extract to dilute, cool and clear smoke from the space, activated automatically or at the discretion of the fire brigade smoke control smoke extract to control the movement of smoke and for which there is a specified performance in terms of: maintenance of a smoke clear layer; maintenance of tenable conditions for either occupants or fire fighters; maintenance of smoke temperature to prevent damage to structure or contents smoke control damper device that can be opened or closed to control the flow smoke and hot gases smoke control zone defined area within a building provided with smoke control to prevent smoke from travelling into adjacent zones SHEVS SHEVS (Smoke and Heat Exhaust Ventilation Systems), a smoke control system which is designed to maintain tenable conditions within smoke or a clear layer beneath it, this is sometimes referred to as throughflow ventilation stagnant Area An area in which there is no airflow passing into or out of it steady state design design based on the largest likely constant heat release rate with which a smoke control system is designed to cope

time dependent design design based on a predetermined time dependant heat release rate with which a smoke control system is designed to cope thrust force created at the discharge of a jet fan. Note: Thrust is a function of velocity and mass and is usually measured in terms of Newtons. vehicle emission ventilation ventilation system designed to remove or dilute to a safe concentration the products of combustion emitted by vehicle exhausts during normal operation