Smoke & Fire detector - Early fire monitoring system for Coal application

By Vinod Gogoriya

Intelligent Gas Alarm India Pvt Ltd

(c) Intelligent Gas Alarm India Pvt Ltd 1

Topics covered:Understanding “Smoke & Fire” and its stagesConventional, existing smoke, fire detection productsLimitations of existing products Basic concept of “very early fire & smoke monitoring

(alarm) system (VEFSA)”Working of VEFSA and its componentsFeatures of VEFSA systemModels, variants of VEFSASizing, selection, designing of VEFSA system Applications & Advantages of VEFSA


Understanding Smoke & Fire:STAGES OF FIRE: 1st stage: Generation of Gas Radicals – Incipient Stage2nd stage: Non-Visible smoke – Smouldering Stage I 3rd stage: Visible smoke – Smouldering Stage II4th stage: Red Hot / Heat stage – Heat Stage5th stage: Fire Flame – Flame Stage



Stage I : Incipient StageThere is no visible smoke, no flame and very little heat. A

significant amount of invisible–but sometimes smellable–combustion particles may be created. This stage usually develops slowly.

Products of Gaseous radicals – mixed hydrocarbon radicals or CO radicals.

Conventional or even VESDA do not respond to these ‘early’ signs of smoke and fire.

VEFSA (Very early fire and smoke monitoring system), based on world-class technology picks up these signs and generate alarm.


Stage II : Smoldering Stage IThere is invisible smoke, but no flame and very little heat.Detectable by aspirating smoke detectors like VESDA

system.


Stage III : Smoldering Stage IIThere is visible smoke with sooth particles, little heat .Detectable by optical, ionisation type smoke detectors.


Stage IV : Heat StageThere is considerable amount of smoke with heat. Detected by heat sensors based on resistance change,

melting of heating elements etc.


Stage V : Fire & flare StageThere will be flares and fire. Damage is DONE. This is stage of damage control, rather

than detection.


Limitations of Conventional, Existing products:Optical, ionisation type smoke detectors

Cannot work in dusty environment, industries, clean rooms, flour mills, pharma/power dust industries

Affected by change in temperature, humidity, vibration, moisture etc Poor response to little smoke or early stage. By the time they

response, its too late Offer false alarms

Heat sensor Respond to very late stage of fire – no much time left before flares


Limitations of Conventional, Existing products:VESDA system

Too complex, costly, high on maintenance Not suitable for every application, industries, particular small

establishment Detect invisible smoke – 2nd stage of smoke & fire

CCTV, flame detector etc. Detect last stage of fire Focused more on damage control, rather than proactive

detection.


Basic of VEFSA system:

Based on detection of earliest signs of smoke Monitor and detects gaseous radicals of hydrocarbons and

carbohydrates (CO+, HC+) These gaseous radicals reacts with sensor electrolyte to generate

proportional response. Continuous Monitoring of these radicals, even before invisible

smoke occurs


VEFSA system – components: Sensing cell / Element

Separate Unit Integral with monitoring & alarm unit

Monitoring & Alarm Unit Standalone unit with integral sensor unit Separate as central unit


VEFSA system – working: Sensing cell / Element

Monitor and measure gaseous radicals in ambient air/ environment Sends signals, continuously to central processing / monitoring unit

Monitoring & Alarm Unit Accepts signals from sensing units Generate alarms, warning signs, sends signal to FAS depending

upon pre-defined limits Adjustable system sensitivity, depending upon application,

industries. Have fault, error alarm, error log PLC Based system with LCD display unit With auto diagnostic watch dog


Features of VEFSA: Offers earliest warning signals, based on gaseous radical generation Proactive system, rather than damage control system Unaffected by dust, temperature, humidity, moisture, vibration,

frequency, radiations etc. Can be mounted in any direction Applicable to any application, industries, area Adjustable sensitivity Auto diagnostic watch dog Fault LEDs, error log No design requirement, low on maintenance, low on installation cost Low initial cost wrt VESDA


Sizing, selection: VEFSA sensor unit works good for 1000-2000 sq ft area (Standard

ventilation, design) Central unit will be designed and selected based on no. of sensor

units. Installation at Ceiling / pillars Mounting in any direction (no orientation problem)


Application Areas: Coal mines, washeries, bunkers, container etc Power plants – coal based Clear rooms, pharmaceuticals, medical, food, powder, flour mills Defence, naval, artilleries stockyard Packing, warehouse etc Basement parking area Cold stores, ripening chambers, plastic industries Shipyard, dockyard, bunkers


Contact Us:

Intelligent Gas Alarm India Pvt Ltd69, Ramgali 7, Raja ParkJaipur 302004Ph: +91-141-4033769, 99833 45452

Web: www.gasalarm.co.in, www.automationindia.inEmail: [email protected]


Date post:	14-Jun-2015
Category:	Technology
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Smoke & Fire detector - Early fire monitoring system for Coal application

Technology