Presentation on theme: "By: Andrew Turchet. What is Aspirated Smoke Detection? In its simplest form a smoke detector Known as: ASD (Aspirated Smoke Detection) ASSD (Air Sampling."— Presentation transcript:
By: Andrew Turchet
What is Aspirated Smoke Detection? In its simplest form a smoke detector Known as: ASD (Aspirated Smoke Detection) ASSD (Air Sampling Smoke Detection)
How does ASD work?
ASD technology utilizes collective air sampling vs. point detection A sample of air is collected from multiple sampling holes Sampling pipe VESDA LaserPLUS 88
= Sample Hole Basic rule of application Areas of coverage and spacing are the same for both
How does ASD work?
Why use ASD? Early warning – achieved thru increased sensitivity and active air sampling Difficult to detect smoke Stable performance in adverse environments Access is difficult
Early Warning Widest sensitivity range available can achieve %obs/ft values a 1000 times greater than conventional photo-electric Active vs. Passive air sampling can capture smoke Collective sampling gives the advantage of pulling together quantities of smoke from many sampling holes. Collectively early warning notification can be achieved.
Early Warning Applications Telecommunications IT / Data Centres Semi-conductor Fab High Value Storage – museums, galleries, libraries, archive.
Telecom & Data Centre High valued equipment Emergency services Critical data storage Down-time causes loss of revenue Early warning reduces the risk from fire
8.2* Automatic Detection Systems. Automatic detection equipment shall be installed to provide early warning of fire. The equipment used shall be a listed smoke detection–type system and shall be installed and maintained in accordance with NFPA 72®, National Fire Alarm Code® * Automatic detection systems shall be installed in the following locations: (1) At the ceiling level throughout the information technology equipment area (2) Below the raised floor of the information technology equipment area containing cables (3) Above the suspended ceiling and below the raised floor in the information technology equipment area where these spaces are used to recirculate air to other parts of the building Where interlock and shutdown devices are provided, the electrical power to the interlocks and shutdown devices shall be supervised by the fire alarm control panel The alarms and trouble signals of automatic detection or extinguishing systems shall be arranged to annunciate at a constantly attended location. A.8.2 Fire detection and extinguishing systems should be selected after a complete evaluation of the exposures. The amount of protection provided should be related to the building construction and contents, equipment construction, business interruption, exposure, and security need. For amplification of the important need of fire protection, see Chapter 4. A The detection system selection process should evaluate the ambient environmental conditions in determining the appropriate device, location, and sensitivity. In high airflow environments, air-sampling detection devices should be considered.
General. Facilities containing greater than 232 m2 (2500 ft2) of signal-processing equipment area shall be provided with a very early warning fire detection (VEWFD) system for detection and alarm processing in accordance with Chapter * Use of VEWFD systems with an alert (pre-alarm) condition shall provide for an initial response by authorized personnel prior to fire department notification VEWFD Sensor and Port Installation * Every type of sensor and port installed in an area shall be limited to a maximum coverage area of 18.6 m2 (200 ft2) * Where two levels (high and low) of ports or sensors are provided, each level shall be limited to a coverage of 37.2 m2 (400 ft2) or less per port or sensor. (A) The coverage limitation between high and low levels shall be limited to 18.6 m2 (200 ft2) or less providing for staggered port or sensor arrangements between each level * Sensors or ports shall be installed to monitor return air from the space. (A) Where stand-alone packaged HVAC units are installed, sensors or ports shall be installed where return air is brought back to the unit. (B) Sensors or ports shall be installed such that each covers no greater than 0.4 m2 (4 ft2) of the return air opening Maximum transport time from the most remote port to the detection unit of an air- sampling system shall not exceed 60 seconds.
Consequences of an incipient fire * US Federal Commission of Communications “95% of all fire damage within facilities housing electronic equipment is non-thermal”
Large amounts of plastics in cabling, circuit boards, etc. Smoldering fire releases harmful corrosive by- products (HF, HBr, ZCl). Can lead to immediate or unexpected failure.
Difficult to Detect Smoke Large open spaces Dilution High air change rates and distribute and dilute smoke Background smoke Adjusting for high ambient “non-fire” related smoke
Difficult to Detect Smoke Applications Atriums Power generation facilities Data Centre Water, waste and sewage treatment facilities Industrial – mining, steel mills, petro- chemical, wood, pulp and paper
Stratification Thermal lift Dilution in large volume Smoke movement by mechanical ventilation
Atriums Sampling at multiple points
High equipment heat output + High cooling demand = High air change rates
Air Change Rate Calculation 1. Air change rate needs to be calculated for all protected areas (i.e. under-floor, room, above ceiling) 2. Determine volume of all protected spaces 3. Sum total CFM for the HVAC system serving the space + fresh air 4. Air Change/Hour = Total CFM x 60min Volume
Smoke Detector Spacing Based on Air Movement Min/Changes Changes per Hour m2 spacing ft2 spacing
Access is Difficult Remote testing Detector and test point can be remotely located to facilitate maintenance Fewer test points
Applications Where Access is Difficult Atriums Energized spaces Prison Cells Confined spaces (crawl, attic) Hazardous areas Elevator shafts Congested ceilings
Last Hole (Test Point) Air-Sampling Detector (Test Point)
Atriums Testing done at most remote point
Prison Cells Sampling is performed in exhaust duct of cell. Testing can be done remotely
Prison Cells Sampling point concealed behind return air grill Out of site out of mind
Correctional sampling point alerts when blocked
Congested Ceiling Spaces
Performing annual inspections can be difficult
Access to under-floor detectors is difficult
Thank you! Andrew Turchet Xtralis (manufacturers of VESDA)