Fire Beam Detectors

FIRE DETECTORS-4

FIRE BEAM DETECTORS

The FSIB introduces the fourth in a series, on types of detectors available for the many and varied applications one might face.

Fire beam detectors

Beam detectors are specialized fire detection devices that use a projected beam of light to detect smoke. These detectors are ideal for large, open spaces where traditional point detectors might not be as effective or practical and can be used at greater heights than that of point type detectors.

Fire Beam detector types.

There are several types of beam detectors, each with unique features and applications

1. Projected Beam Detectors: These use a beam of light projected from a transmitter to a receiver. Any smoke or heat that interrupts the beam triggers the alarm.

2. Reflective Beam Detectors: In these systems, the beam is reflected back to the transmitter by a reflector. The presence of smoke reduces the intensity of the returned beam, triggering the alarm.

3. Open-area Smoke Imaging Detection (OSID) combines advanced dual-wavelength projected beams and optical imaging technology for early warning smoke detection. Multi-emitter solutions provide a true 3D arrangement. This type of beam detector supports up to seven emitters with a single receiving Imager giving the advantage of covering unusual, shaped areas.

4. The Motorised beam detectorself-aligns to the centre of the reflector during commissioning and will automatically keep alignment when building movement occurs. The motorised beam head continually self-aligns during its installed life. This intelligent motorisation can result in fewer false alarms.

Applications

Beam detectors are commonly installed in locations where large, open spaces or high ceilings exist, such as:

Warehouses        Atriums     Auditoriums    Industrial facilities    Tunnels

Beam detectors can be installed above the height that traditional smoke detectors can operate.

How do they work?

Beam detectors function by emitting an invisible beam of light (usually infrared) across a protected area. When smoke enters the beam path, it scatters the light, reducing the amount of light received by the detector. This reduction triggers the alarm. In some advanced models, the system can differentiate between smoke and other particles, reducing false alarms.

Where should we NOT use it?

Optical beams are subject to movement and building structures that expand, and contract causing the beams to go out of alignment.

Optical beams require line of site, where obstruction from high stacking of goods or where birds may fly around will cause the detectors to false alarm.

Where must it be installed?

Point type conventional and addressable smoke detectors cannot be installed above 10.5m from the ground, here is where the beam detector comes into its own, as it can be installed at heights of up to 20m from the ground.

Ideal for high open plan areas such as warehouses. It only has one competitor at elevated levels.

Installation Guidelines

When installing beam detectors, consider the following guidelines:

1. Mounting: Install the detectors at the highest point where smoke will accumulate, typically within 600mm of the ceiling or ten percent of the overall roof height. (considering further recommendations of SANS 10139).
2. Alignment: The beam must be accurately aligned with the receiver or reflector. Special instructions or tools are provided for this. Some units have the capability to auto-align, which can help compensate for the movement of buildings.
3. Spacing: Adhere to the manufacturer’s recommendations for spacing, while following the guidelines provided in SANS 10139. Typically, these guidelines allow spacing of up to 15m apart with a maximum distance of 7.5m from each side wall. These distances can be increased in conjunction with the slope of the roof as specified in the national standard.

The beam detectors can cover distances up to 100 meters, though some kits may provide protection of even greater distances. One beam detector can cover a maximum of 2000m²

4. Beam path clearance: A clearance radius from 500mm up to 1000mm of the beam path is often required by the manufacturer’s instructions.

5. Maintenance: Regular cleaning and testing the detectors will ensure optimal performance. The lens of the beams can accumulate dust so should be cleaned regularly.

Advantages of Beam Detectors

Beam detectors offer several advantages in fire detection, particularly in large or high-ceiling environments:

1. Coverage: They can cover large areas, significantly reducing the number of detectors needed.

2. Cost-Effective: Fewer detectors can mean lower installation and maintenance costs.
3. Early Detection: They provide early warning by detecting smoke along the entire length of the beam path, this can sometimes span the length of warehouses.
4. Minimal Aesthetic Impact: Beam detectors are less obtrusive, helping maintain the aesthetic look of the building.

Have you suffered false alarms?

While beam detectors are less prone to false alarms than some other types of detectors, they can still be affected by dust, fog, physical obstructions and building movement. Regular maintenance and proper installation can help mitigate these issues.

Conclusion

Beam detectors are an excellent choice for fire detection in large, open spaces. Their ability to cover extensive areas, coupled with their cost-effectiveness and early detection capabilities, makes them a valuable addition to any fire safety system