1 aspirating systems training e-series. 2 air sampling system design principle of operation stages...

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ASPIRATINGSYSTEMS TRAINING

e-series

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Air Sampling System Design Principle of operation Stages of Fire General System Design Pipe layout considerations Secondary Air-sampling Systems Primary Air-sampling Systems Referencing – ambient pollution compensation Effect of dilution on sensitivity Response time PipeTracer Adverse Environments

System Components Maintenance

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Air Sampling System Air drawn through pipe network to central system High sensitivity smoke detector Laser detection of particles for very early warning Adjustable alarm thresholds 0.005 – 20%

obscuration/metre Pin-point addressing with sampling from up to 15

channels

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FHSD700 pulls air samples from the sampling channels

simultaneously

Air samples are drawn through a chamber where a laser beam illuminates any smoke particles, with a sensitivity of five parts in

one hundred thousand

Within seconds it will inform the user exactly which channel contained the contaminated sample

When smoke is detected the FHSD700 quickly samples each individual channel

Allowing the user to locate the hazard and prevent it progressing

Principle of Operation

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Obs/metre : 10.0 FULL FIRE

Possible loss of premises, stock and life

Example

Office Chair placed against heater

Obs/metre : 0.1 Est. time to Fire : 45m

Smoke not yet visible.Standard point detectors have not yet

raised alarm

Obs/metre : 0.03Estimated time to Fire : 1 hr

Very fine smoke particlesFHSD700 series sounds alert

Identifying fires within its incipient stages for earliest possible protection

0.01 0.1 1.0 4.0 10 20

Stages of Fire

Obs/metre : 4.0 Est. time to Fire : 0m

Flames appear and the office must be evacuated. The FHSD700 will activate

combined suppression systems

Obs/metre : 1.0 Est. time to Fire : 10m

Smoke clearly be seen.Conventional detectors sound alarm

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General system design Define requirements/expectations at an early

stage. What sensitivity is expected from the system

Two main types of system With Air Handling Units (AHUs) Without Air Handling Units

Special cases include clean rooms, cold rooms, historical buildings

Perform smoke tests to ascertain patterns of air movement and position sampling points where smoke will propagate to.

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Pipe Layout Considerations

Pre-design pipe network, especially for wide-bore pipes

Use a square grid overlay 6mx6m 8mx8m 8mx6m Ensure maximum pipe length is not be exceeded

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Large bore systems - Pico, FT1, FT4, FT6 Use capillary

tubes (8mm id with 2mm end hole up to 6m long) or drop pipes for concealed or cabinet sampling

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Microbore systems - FT15 Flexible nylon 6mm o.d. sampling tube. Fast and simple installation in cabinets or within building structure Outputs and flow monitoring for every sampling point One tube can be used for referencing 2 way split (2m) allowed at end of tubes allowing 30 sampling points

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Secondary air-sampling systems•Air sampling placed in same places as conventional detectors and not relying on air conditioning systems•Designed to BS5839/6266 and EN standards for spacing and placement.

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Primary air-sampling systems•System designed to work in conjunction with an air handling or ventilation system•Only provides optimum performance when air handling system is operational•Detects trace levels of smoke that do not have the thermal energy to rise to the ceiling

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Primary air-sampling systems - AHUs

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Primary air-sampling systems - AHUs

•Cover entry to Air Handling Unit not exhaust as this is filtered•Sampling holes at 200mm intervals across AHU grille facing into airflow•Extract ducts in shallow floor voids have high negative pressure and therefore sampling points should be positioned in front of but at least 2m away from the entry point

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Primary air-sampling - Ducts•Use Probe to penetrate return air duct allowing sampling holes to be directly in air path•Ensure intake and exhaust probes are separated by 300mm and are properly sealed – high negative pressures exist•Ensure probes are diagonally offset to avoid turbulence reaching exhaust probe

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Primary air-sampling - Clean Rooms•Earliest detection possible required to avoid damage from smoke contamination•FT15 ideally suits application by monitoring individual cabinets and processes before the air is diluted and filtered•Conventionally sited air-sampling networks struggle with the high airflows & ultra high dilution

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Referencing - Ambient pollution compensation

Take referencing air-sample from building air inlets

Provides compensation for ambient pollution Use additional detector on RS485 network Use one sampling tube on system for integral

referencing Set parameters for reference compensation and

time delay

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Effect of Dilution on Sensitivity

Smoke entering a sampling hole is diluted by sampling holes closer to the detector

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Table Showing Varying Dilution

This depends on many different factors but this can be used as a rough guide for large bore systems

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Response Times Response times are dependent on several

factors Number of pipes Diameter of pipes Pipe length Distance to first bend Number of holes Hole spacing Aspirator speed and performance

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PipeTracer

Response times are calculated using PipeTracer software

Detailed information about the intended layout is entered

PipeTracer calculates all response times, flow volumes and hole balances together with sensitivity at each sampling hole

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Adverse Environments Cold Stores / Chill Stores

Drill sampling holes in side of pipe Ensure pipes drop along length of store towards detector No vertical pipes Heat air sample outside store before entering FHSD Fit water trap – loop of flexible pipe before detector Keep pipes away from chiller exits

Dusty areas, and Mines Use Filter+ pre-filter

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Adverse Environments Hazardous Areas

Install FHSD in safe areaUse in-line flame arrestors on interface

between safe and hazardous area Atria

Install vertical pipes to cover varying height of smoke stratification layer as temperatures change during day

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System Components Laser Detector Aspirator Fan High pressure pump Rotary Valve Control Panel Control & I/O System Power Supply

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Laser Detector A laser fires radially across optical chamber Any smoke particle is illuminated The scattered light is caught in the wall of the chamber

which acts as a light-guide providing a total integration of the light from the smoke particles

A particle density of 0.005% obscuration/metre is detectable with maximum range of 20% obscuration/metre

Chamber is field removable for ease of service

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Aspirator Fan – Pico, FT1, FT4, FT6 High performance high static pressure

enabling detection over 100m pipe lengths with minimum response times

Full speed control Includes by-pass sampling to preserve

filter life

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High pressure pump - FT15

Allows use of 4mm microbore tubing Carbon rotor & vanes for long life Stainless steel body for long life Vacuum sensor provides flow monitoring

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Rotary Valve - FT4, FT6, FT15 Rotary valve for monitoring samples taken by up

to 15 individual pipes Wide-bore application for ¾ inch pipe Small-bore application for high pressure systems Normally monitors all sectors - when trace level

exceeded rotary valve immediately sequences to pinpoint sector

Individual pipe flow monitoring

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Control Panel

Recognisable symbols for international markets Multi-language display settings Simple interface for easy configuration All alarms and faults clearly displayed to enable

immediate identification Obscuration per metre level constantly visible Programmer RS485 remote interface

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Control & I/O System

Fully programmable system for continuous early warning detection of hazard

Optional web support for remote monitoring using TCP/IP and Ethernet

Optional input/output cards for relay contacts, auxiliary input/output and fire suppression

RS485 connection for remote location of control panel

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Power Supply

Integrated mains power pack in either 230/115 Volt options

Battery compartment for 2 x 17Ah batteries included

Power pack provides 5Amp charge and trickle charge for batteries

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Maintenance Optical chamber and filter cartridge – inspect at

every regular service - clean chamber and replace filter if necessary

Check all internal pneumatic connections for leaks

Check pipe network flow levels Perform smoke test Replace pump vanes annually FT15 only Replace rotary valve seals every 3 years FT4, FT6 and FT15 only