1. ASPIRATING SYSTEMS TRAINING
e-series

2. 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

3. 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 – 20% obscuration/metre
Pin-point addressing with sampling from up to 15 channels

4. 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

5. 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 : 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

6. 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.

7. 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

8. 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

9. 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

10. 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.

11. 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

12. Primary air-sampling systems - AHUs

13. 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

14. 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

15. 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

16. 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

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

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

19. 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

20. 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

21. 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

22. 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

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

24. 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

25. 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

26. 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

27. 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

28. 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

29. 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

30. 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

31. 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