Air Sampling Smoke Detection Systems by ajh17208

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									               Air Sampling Smoke Detection Systems

Section I: Inspection, Testing and Maintenance Requirements

Semi-Annual Frequency (2-times per year)

Control Equipment and Detector


       Inspection
                    Verify equipment has no physical damage, not obstructed and is in
                    normal operating condition.
                    Illuminate all lamps and LEDs on all display modules.

Power Supply

       The power supply of the Air Sampling Smoke Detection System falls under
       the requirements for Fire Detection and Alarm Systems and shall be
       inspected, tested and maintained accordingly.

Sampling Pipe Network


       Inspection
                    Inspect the sampling pipe network and connections to ensure that the
                    pipe runs are intact with no breaks (ex. pipe joints, end caps, capillary
                    tube connections).


       Maintenance
                 Repair broken or loose pipe joints or caps when necessary.


Annual Frequency (1-time per year)

Control Equipment and Detector


       Inspection
                    Check the filter for excessive dust and/or clogging. Depending on the
                    environment, this may be required more-frequently.
                    Check the raw airflow of the detector and compare to previous
                    readings to see that it is not progressively decreasing.



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      Testing
                   Perform test to verify all functions of the control equipment and
                   detector will operate properly. This includes supervision, outputs,
                   isolate and other features specified by equipment manufacturer.


      Maintenance
                Clean or replace filter when necessary.

Power Supply

      The power supply of the Air Sampling Smoke Detection System falls under
      the requirements for Fire Detection and Alarm Systems and shall be
      inspected, tested and maintained accordingly.

Sampling Pipe Network


      Inspection
                   Inspect the sampling pipe network to be clean and free of dirt that can
                   cause blockage by injecting a small amount of smoke into the last
                   sampling hole to ensure detector response.


      Testing
                   Test the performance of the sampling pipe network by measuring the
                   suction pressure for each sampling hole and comparing to the airflow
                   modeling software results.
                   Test the transport time of the sampling pipe network by introducing a
                   smoke sample into the sample point furthest from the detector and
                   measuring the response time. Compare this time with the airflow
                   modeling software results.


      Maintenance
                Clean sample pipe network if found clogged or breached with dirt.




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Every 2-Year Frequency

Sampling Pipe Network


       Maintenance
                 Clean all capillary tube sampling points to remove dust build-up that
                 can cause blockage.
                 Back-flush the sampling pipe network to remove dust build-up that
                 can cause blockage. (see Manufacturer Guidelines for proper
                 procedure)


Every 4-Year Frequency

Control Equipment and Detector


       Maintenance
                 For Xenon Light Source Detectors Only: Replace the detector with a
                 refurbished detector.




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Section II. Explanatory Material

Operation

Air Sampling Smoke Detection System Operation

The AIR SAMPLING SMOKE DETECTION SYSTEM is a new concept in Very Early
Smoke Detection. It couples a highly responsive smoke detection system with a new
modular design. The AIR SAMPLING SMOKE DETECTION SYSTEM’s new laser
chamber is ultra-sensitive and can provide the earliest possible warning of a potential fire
by detecting minute quantities of smoke. The modular design of the new AIR SAMPLING
SMOKE DETECTION SYSTEM gives you the flexibility to build up the exact system you
require at minimum cost—redundant devices are eliminated. Its unique design results in
low maintenance costs.

Air Sampling Smoke Detection System Principles

Both fire and fire suppression systems can result in loss of life and damage to property.
The AIR SAMPLING SMOKE DETECTION SYSTEM can minimize the effects of a fire by
detecting very low levels of smoke and sounding an alarm before visible smoke and flames
are present. Thus problems can be dealt with promptly.

While a fire can cause loss of life and damage to facilities, plant down-time during repairs
and removal of fire suppressants after a fire is another major problem . A system that
detects smoke very early in a fire is extremely desirable. The AIR SAMPLING SMOKE
DETECTION SYSTEM has this capability.

The AIR SAMPLING SMOKE DETECTION SYSTEM is able to detect a fire at its incipient
stage—before flames are visible by using a highly sensitive laser smoke detector. The
AIR SAMPLING SMOKE DETECTION SYSTEM uses an aspirator (air pump) to supply air
samples continuously to the detector, even in areas of low/high air flow.

Air Sampling And Aspiration

The AIR SAMPLING SMOKE DETECTION SYSTEM is an active smoke detection system
that samples air from a fire zone to detect the presence of smoke. It continuously draws in
air samples by means of an integral aspirator and is not reliant on air currents in the
vicinity of the detector to bring smoke particles into the detector. As such, the AIR
SAMPLING SMOKE DETECTION SYSTEM can function effectively in all kinds of
environments—from high air flows to still air.

Smoke is brought to the detector through the air sampling pipe network. This consists of a
series of sampling pipes containing a series of sampling points. This method of sampling
allows one detector to examine air from many places, and so the effective cost per sample
point is reduced. Also, as the detector is highly sensitive it can detect very low levels of




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smoke. Low cost piping means that even the most complex sampling network can be
inexpensively and simply installed, while maintaining maximum efficiency.

The sampling points in the AIR SAMPLING SMOKE DETECTION SYSTEM are often
situated where conventional spot-type detectors would be placed. However, since it is
possible to have many sampling points in a pipe at negligible cost, a better coverage can
be provided by an AIR SAMPLING SMOKE DETECTION SYSTEM than can economically
be obtained from spot-type detectors. The active sampling of air using an aspirated system
also makes the system much more effective at detecting low levels of smoke than spot-
type detectors.

Smoke Detection

Smoke levels are defined as percentage obscuration per meter (% obs/m) or per foot (%
obs/ft). This is analogous to the reduction in vision a person would suffer during afire.

Conventional spot-type detectors use either ionization chambers or photoelectric scattering
to detect smoke. The best spot-type detectors operate at around 0.5% obs/m obscuration
(or 0.15% obs/ft). The AIR SAMPLING SMOKE DETECTION SYSTEM’s smoke detection
is achieved by measuring the light scattered by the smoke when it is illuminated. The
amount of scatter can be used to determine the obscuration, with detection thresholds of
0.005% obs/m (0.00 15% obs/ft) attainable. The high sensitivity makes it possible to detect
a fire, or potential fire, long before it is flaming and so damage can be minimized.

Connecting To Other Systems

AIR SAMPLING SMOKE DETECTION SYSTEM’s are typically integrated into other fire
alarm or building management systems. This means that they are often used to raise pre-
alarm and alarm conditions as well as action automatic emergency procedures and shut
down ventilation systems.

The AIR SAMPLING SMOKE DETECTION SYSTEM has four smoke alarm thresholds.
These cover smoke obscuration levels from 0.005 to 20% obs/m (0.0015 to 6% obs/ft).
Each threshold has a confirmation delay and can be varied with time of day. There are
also fault and isolate conditions which can be reported to dedicated relays.

More intelligent interfacing of the system is possible using specially designed High Level
Interfaces (HLIs). These can be used to connect the AIR SAMPLING SMOKE
DETECTION SYSTEM network to external devices such as a PC.




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About the System

Detector

The AIR SAMPLING SMOKE DETECTION SYSTEM detector uses a specially-designed
aspirator to maintain air flow from the sampling pipe network. The sampled air is passed
through a laser chamber that checks for the presence of smoke.

The detector unit can be fitted with modules such as a display or an LCD Programmer, or
in larger systems it can simply detect smoke levels and relay these to remotely mounted
units.

Display Modules

Display modules are used to monitor the AIR SAMPLING SMOKE DETECTION SYSTEM.
Each display shows a visual representation of the smoke levels detected by the particular
detector to which it is connected so you can see at a glance the seriousness of the
situation.

Faults in the detector module, as well as faults in the system (e.g. power supply or air flow)
are indicated on the displays enabling easy tracing.

Display modules can be located anywhere and several displays can be associated with a
single detector enabling it to be monitored remotely.

Network Communication

The AIR SAMPLING SMOKE DETECTION SYSTEM’s communications network is a fault
tolerant communications network with redundancy that connects all devices in the AIR
SAMPLING SMOKE DETECTION SYSTEM system. That is, if wiring is damaged or a unit
is un-powered then communications can continue. AIR SAMPLING SMOKE DETECTION
SYSTEM devices are optically isolated from each other and are wired in a loop. These
devices continuously monitor the state of health of their neighbors. If a fault occurs then
the devices either side of the fault reflect messages back around the loop and inform the
network that a fault has occurred. This allows the faulty device or wiring link to be identified
while allowing all the other devices to continue to operate normally.

Programmers

An LCD programmer module allows the system to be configured, commissioned and
maintained. This can be located anywhere in the system and only one such programmer
module is required to maintain the entire network. A hand-held version is available and this
can connect to the system via a network socket located either on a detector or in a remote
location.




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In addition to the LCD programmer, the communications network can be connected to an
IBM PC (or compatible) using a PC-Link High Level Interface or a PC configurator
software. This enables the PC to be used to configure AIR SAMPLING SMOKE
DETECTION SYSTEMs.

Scanner Version

The scanner version of the AIR SAMPLING SMOKE DETECTION SYSTEM allows air to
be sampled from several protected areas simultaneously. It enables one detector to cover
several sectors within one fire zone.

Initially air from all sectors of the zone flows through separate pipes to the detector. On
detection of smoke above a pre-programmed level the scanner-type detector begins
sampling each pipe individually until it finds the sector with the highest smoke level. The
detector then reports this information to its relays and the communications network.
Displays then show the sector number where smoke is detected on its numerical readout.

Power Distribution

AIR SAMPLING SMOKE DETECTION SYSTEM devices accept 18 to 30 V DC power. Any
associated AIR SAMPLING SMOKE DETECTION SYSTEM power supply incorporates all
the required features of a Fire System Power Supply. It monitors mains power input and
the connunications network to mains power failures. It can perform battery condition
monitoring and predict reserve capacity.

When multiple power supplies are used together, each device on the connunications
network recognize its own power source. If the battery condition deteriorates or battery
backup operation begins on a particular power supply, the devices powered by this source
will report a fault. The AIR SAMPLING SMOKE DETECTION SYSTEM power supply
therefore provides an integrated solution to powering the system.




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