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Aspirating Smoke Detection Systems

Fire Detection Systems

Aspiration detection systems are a highly sensitive form of detection which can detect a fire at the earliest possible stage. It takes air samples and consistently monitors them for the presence of smoke.

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Aspirating Detection Systems

Aspirating fire alarm systems are required to protect life and property. All Aspiration systems need to comply with BS5839-1 to ensure the safest practice.

ClearView can supply, install, maintain, and commission all types of aspiration smoke detection systems to the highest standards. 

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Aspiration Detection Features
How Does an Aspirating Fire Detection System Work?

Aspiration systems come in two types: Normal (ASD) and high sensitivity (HSSD). Aspirating smoke detectors use sampling pipes with multiple holes within the protected area. A fan unit consistently draws air through the pipes. As this happens, the air filters through the system. Any contaminants are removed when filtering the air to avoid false alarms before processing through the detection system.

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Where is it installed and why?
Aspirating Fire Alarm Installation

Aspirating Smoke Detection Systems

Aspirating smoke detection systems are mainly used within data centres/cold stores/inaccessible areas due to their rapid smoke reaction. It is used in non-accessible areas because it can be tested outside of its place of protection, meaning you can install a test point outside the protected area.

ASD systems are satisfactory for environments where sensitive smoke detection is required (goods easily damaged by fire/data centres/highly flammable liquids or gasses). They are also used in common areas where point detection is not aesthetically suited (open ceiling offices, hotels). ASDs are also useful in areas that are not ‘maintainable’. As per BS5839-1, any devices installed must be maintained by a servicing company. Therefore sites that can not be accessed (i.e. top of lift shafts) can use ASD.

It is commonly installed to the fabric of the building, using special clips that allow it to sit just off of the protected ceiling. It is installed with a servicing point, usually outside the protected area (if the pipe itself is not maintainable).

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There are 3 classes to be considered when dealing with ASD systems.
Sensitivity Classes

Class A – Very High Sensitivity

This class can provide a very early warning when detecting smoke. These systems are relevant to high-risk locations, where staged responses to the multistage alarm conditions are clarified. This will guarantee minimum downtime of the protected locations in a fire-related incident.

Class B – Enhanced Sensitivity

Class B ASD systems are required to enhance sensitivity for purposes where additional confidence is mandatory for protecting a particular risk. The greater capability of such systems is used to counteract other risk factors in the protected area, such as extraordinarily high ceilings or significant air flows.

Class C – Normal Sensitivity

An ASD system that gives equal operation as standard point detection systems, meeting the requirements of the British Standards, EN 54-7.

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Limitations of an Aspirating Smoke Detection System

Though ASD systems are an excellent option for fire detection systems, there are limitations to using them, mainly ceiling heights. Please see the below table from the FIA.

Limitation of an ASD

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Smoke Transport Time

The time taken for a system to carry a smoke sample from a protected area should not surpass 120 seconds (two minutes). Transport times more than this must be the issue of a variation against BS5839-1 and documented on the fire alarm commissioning and installation certificate. Systems may need quicker and more efficient transport times for conformity with their EN 54-20 product approval and should be clarified in your fire risk assessment. For example, a Class A aspirating fire detection system is usually intended with transport times of fewer than 60 seconds, where an early warning is the objective.

The layout of the sample pipe can directly influence most transport times. The 4-branch design (See below) will provide the shortest transport time.

asd pipe design

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