Most people are familiar with conventional smoke detectors, which are placed on the ceiling of offices, kitchens and hallways. In industrial, commercial, historical or government sites, many of these can be linked together in a network to protect large areas. Typically for smoke or flame to rise to ceiling level and activate these detectors requires considerable heat buoyancy, by which stage considerable fire damage to equipment will usually have taken place.
Les Mitchell, National Sales Manager of Failsafe Fire Projects discusses very early warning fire detection using ICAM fire and gas detection systems.
Why multipoint fire detection?
The key function of an early warning fire detection system is to provide detection at the earliest stage of a fire prior to combustion, then to take the necessary action to prevent a real fire so that major equipment and consequential loss can be avoided.
An important application for such air sampling systems is the protection of computers or process control systems housed in a secure area. These areas are usually of brick or concrete construction and with good working practices, the major fire risk lies with the equipment and not the room.
Why not cover the area that the fire is expected to start from?
The usual way to approach this type of risk has been to put sampling pipes on the return air ducts or grills of the air handling units. Smoke from the protected units will always travel to these points, giving an earlier response than conventional point detectors, but will be considerably diluted, having been mixed with the entire air volume in the room.
Monitoring the units directly and not the entire room can achieve a faster response, due to the much less diluted smoke signal and the real benefit of identification of the source of the incident.
Says Mitchell, "The FireTracer system works on these principles by sampling air inside of the units and by indicating 'first and second up' warnings, allowing the operator to identify the source and the direction of spread of the incident. The search time of the operator is much reduced, and only units affected need be shut down, a crucial advantage where entire plant production can be dependent on the protected control system. Using small bore pipe the installation is also far more cost effective and less disruptive to the equipment covered."
Method of operation
The system works by continuously drawing air from all pipes covering the protected areas. The first indication of an incipient fire condition is on the 'all zones' monitor, which is pre-set to respond at a 'trace' level with a programmable time delay. Once this is exceeded, the unit will automatically sequence through the individual sampling pipes until it finds the source of the incident.
Dependent on the amount of smoke present the corresponding alarms will be raised, of which there are three levels, all programmable and offered via clean contacts. Says Mitchell, "The first alarm indication can be given at the trace level on the overall monitor and then two further alarm thresholds can be programmed for each individual sampling pipe. The sensitivity of the FireTracer is 0,01% obscuration per metre, or one part in ten thousand."
In addition to the three alarm thresholds, common fire and common fault contacts are available.
System flexibility
As well as the individual and common fire and fault contacts, the overall system and individual zones can be programmed with their own unique sensitivity settings. Additional inputs and outputs are included in the form of RS485 and RS232 for data logging and connection to remote display units and the ICAM WinTracer Graphics package. Digital inputs and additional analyser ports are also included. The units are complete with power supply unit, charger and 24-hour battery back up. The programmer for systems set-up and diagnostics is on board.
Installation flexibility
The units are designed primarily to give pinpoint location of the source of an incipient fire condition within a computer cabinet, electrical substation or in an equipment rack. They can equally successfully be used to cover air conditioning units return air grills, ducts and large open areas by employing a variety of proven air sampling techniques.
Adds Mitchell, "For large open areas, the use of the ICAM Air Collector Unit gives a practical and economic solution for this type of risk. In most circumstances environmental monitoring of the equipment room can be employed by using one of the sampling pipes. A single FireTracer system can therefore cover individual cabinets, ceiling and floor voids, air handling units and the environment of the room."
Unique features
The rotary gas-switch was designed by ICAM twelve years ago as a compact multichannel air sampler with the unique combination of overall sample chamber and individual sample selection. It has been used in many fire and gas sampling applications including military installations, on-shore/offshore oil and gas plants, ships ballast tanks, historic buildings, detention centres, nuclear electric plants and many other commercial and industrial applications around the world.
"For the first time, it is now possible to incorporate both incipient fire and gas detection with a single sampling installation and monitoring package," he adds. Typical applications for this dual system are cold stores for the detection of smoke and refrigerant leakage, battery rooms, pharmaceutical production and clean rooms.
WinTracer monitoring, recording and control software
WinTracer 5.0 is the latest version of ICAM's site monitoring software for Windows 95/98 and NT. Once it has been installed users can monitor one or more ICAM systems [Fire or GasTracers] and networks of conventional fire panels/detectors. WinTracer 5.0 is based around site maps, so one can see exactly where an alarm or a fault has occurred.
The gas tracer
"The range of multipipe sampling systems used in the GasTracer instruments uses the same control package as the FireTracer systems, using gas analysers and detectors instead of high sensitivity smoke detectors," says Mitchell. "The gas or gases that require detection or analysing are not limited to any particular type or range, and the system is flexible enough to accommodate most types of gas detection or analysis.
"It can be set-up for ranges of % LEL, PPM or PPB with up to four different gas detectors with either a single gas or a combination of gases offered. The same unique programming is offered as with the FireTracer range, offering economy with flexibility," he concludes.
For details contact Les Mitchell, National Sales Manager of Failsafe Fire Projects on tel: (011) 421 5085, or e-mail: [email protected]
Failsafe Fire Projects is the southern African principal for the British manufacturer ICAM. ICAM is unique in that it is capable of monitoring for fire and gas. It is available in a variety of sizes, from the compact unit for rooms with a volume of less than 70 m3 through one zone, 4, 6, 8, 15, and 30 zone units.
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