ASPIRATING SYSTEMS TRAINING e-series

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

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

Principle of Operation When smoke is detected the FHSD700 quickly samples each individual channel FHSD700 pulls air samples from the sampling channels simultaneously Within seconds it will inform the user exactly which channel contained the contaminated sample 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 Allowing the user to locate the hazard and prevent it progressing

Stages of Fire Identifying fires within its incipient stages for earliest possible protection Obs/metre : 0.1 Est. time to Fire : 45m Smoke not yet visible. Standard point detectors have not yet raised alarm Example Office Chair placed against heater Obs/metre : 1.0 Est. time to Fire : 10m Smoke clearly be seen. Conventional detectors sound alarm Obs/metre : 10.0 FULL FIRE Possible loss of premises, stock and life Obs/metre : 0.03 Estimated time to Fire : 1 hr Very fine smoke particles FHSD700 series sounds alert Obs/metre : 4.0 Est. time to Fire : 0m Flames appear and the office must be evacuated. The FHSD700 will activate combined suppression systems 0.01 0.1 1.0 4.0 10 20

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.

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

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

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

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.

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

Primary air-sampling systems - AHUs

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

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

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

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

Effect of Dilution on Sensitivity Smoke entering a sampling hole is diluted by sampling holes closer to the detector

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

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

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

Adverse Environments Cold Stores / Chill Stores Dusty areas, and Mines 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

Adverse Environments Hazardous Areas Atria Install FHSD in safe area Use 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

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

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

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

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

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

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

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

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

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