Aspirated Smoke Detection By Andrew Turchet Aspirated Smoke

Aspirated Smoke Detection By: Andrew Turchet

Aspirated Smoke Detection What is Aspirated Smoke Detection? • In its simplest form a smoke detector • Known as: • ASD (Aspirated Smoke Detection) • ASSD (Air Sampling Smoke Detection)

Aspirated Smoke Detection How does ASD work?

Aspirated Smoke Detection ASD technology utilizes collective air sampling vs. point detection Sampling pipe VESDA Laser. PLUS • A 88 sample of air is collected from multiple sampling holes

Aspirated Smoke Detection Basic rule of application Sample Hole = • Areas of coverage and spacing are the same for both

Aspirated Smoke Detection How does ASD work?

Aspirated Smoke Detection 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

Aspirated Smoke Detection 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.

Aspirated Smoke Detection Early Warning Applications • Telecommunications • IT / Data Centres • Semi-conductor Fab • High Value Storage – museums, galleries, libraries, archive.

Aspirated Smoke Detection Telecom & Data Centre • High valued equipment • Emergency services • Critical data storage • Down-time causes loss of revenue • Early warning reduces the risk from fire

Aspirated Smoke Detection NFPA 75 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®. 8. 2. 1* 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 8. 2. 2 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. 8. 2. 3 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. 8. 2. 1 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.

Aspirated Smoke Detection NFPA 76 6. 8. 6. 1 General. Facilities containing greater than 232 m 2 (2500 ft 2) 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 8. 8. 4. 1. 3* Use of VEWFD systems with an alert (pre-alarm) condition shall provide for an initial response by authorized personnel prior to fire department notification. 8. 5. 3. 1. 2 VEWFD Sensor and Port Installation. 8. 5. 3. 1. 2. 1* Every type of sensor and port installed in an area shall be limited to a maximum coverage area of 18. 6 m 2 (200 ft 2). 8. 5. 3. 1. 2. 2* Where two levels (high and low) of ports or sensors are provided, each level shall be limited to a coverage of 37. 2 m 2 (400 ft 2) or less per port or sensor. (A) The coverage limitation between high and low levels shall be limited to 18. 6 m 2 (200 ft 2) or less providing for staggered port or sensor arrangements between each level. 8. 5. 3. 1. 2. 3* 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 m 2 (4 ft 2) of the return air opening. 8. 5. 3. 1. 2. 6 Maximum transport time from the most remote port to the detection unit of an airsampling system shall not exceed 60 seconds.

Aspirated Smoke Detection • Consequences of an incipient fire “ 95% of all fire damage within facilities housing electronic equipment is non-thermal” * US Federal Commission of Communications

Aspirated Smoke Detection • Large amounts of plastics in cabling, circuit boards, etc. • Smoldering fire releases harmful corrosive byproducts (HF, HBr, ZCl). • Can lead to immediate or unexpected failure.

Aspirated Smoke Detection 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

Aspirated Smoke Detection Difficult to Detect Smoke Applications • Atriums • Power generation facilities • Data Centre • Water, waste and sewage treatment facilities • Industrial – mining, steel mills, petrochemical, wood, pulp and paper

Aspirated Smoke Detection Atriums

Aspirated Smoke Detection Atriums • Stratification • Thermal lift • Dilution in large volume • Smoke movement by mechanical ventilation

Aspirated Smoke Detection Atriums • Sampling at multiple points

Aspirated Smoke Detection High equipment heat output + High cooling demand = High air change rates

Aspirated Smoke Detection 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 60 min Volume

Aspirated Smoke Detection Smoke Detector Spacing Based on Air Movement Min/Changes 1 2 3 4 5 6 7 8 9 10 Changes per Hour 60 30 20 15 12 10 8. 6 7. 5 6. 7 6 m 2 spacing ft 2 spacing 11. 61 125 23. 23 250 34. 84 375 46. 45 500 58. 06 625 69. 68 750 81. 29 875 83. 61 900

Aspirated Smoke Detection Access is Difficult • Remote testing • Detector and test point can be remotely located to facilitate maintenance • Fewer test points

Aspirated Smoke Detection Applications Where Access is Difficult • Atriums • Energized spaces • Prison Cells • Confined spaces (crawl, attic) • Hazardous areas • Elevator shafts • Congested ceilings

Air-Sampling Detection Overview • Annual inspection is performed at most remote sampling hole on each pipe Last Hole (Test Point) Air-Sampling Detector (Test Point) • Record transport time and compare