In prisons more than in most environments, a balance has to be struck between early and accurate detection and avoiding false alarms. Simon Foulkes product manager at Gent by Honeywell, reports on a series of Home Office monitored tests.
In almost all cases it can be assumed that protection against fire is something that the occupants of the buildings want. But there are situations where intentionally defeating a fire protection system is often the aim of those in the environment. Even worse is the situation where occupants are determined to cause themselves self-harm and have, in some instances, elected to do this by means of fire.
In prisons, these situations need to be considered, with the additional risk that inmates may even want to start and use a fire to a cause a disturbance, or even facilitate an escape attempt.
In order to create an effective fire protection system in prisons and provide individual cell-by-cell protection, manufacturers need to think beyond the basic point source detector, traditionally sited in living and sleeping accommodation. The current, most common solution is to use duct detection, which simply involves a number of cells being protected by a detector sited in the plant duct which provides ventilation for a number of cell-blocks in that section. But the effectiveness of this approach will be limited by such factors as the distance from the cell to the detector – the further away the detector, the greater the reaction time.
In order to give the best possible protection to inmates, it is imperative that staff can locate the seat of the fire as quickly as possible, so cell identification is vital. This level of detail cannot be given from the duct detector solution, as the information provided will only relate to the whole block of cells served by the duct detector. Furthermore, the HVAC system may not continue to work in the event of power failure and so should, at the very least, be monitored by the fire detection system or have full standby capacity in accordance with the design.
Some have investigated the use of a standard point detector mounted behind a tough vandalproof protective mesh, to make it immune to all but the most determined malicious damage. But even if the prisoner isn’t able to damage the actual detector, malicious activation is still too easy. Add to this the risk of injury or death by ligature using the protective mesh in front of the detector and this solution becomes less attractive.
Home Office input
The Home Office has indicated that it needs detection systems to identify in which particular cell a fire has started. And as more incidents of self harm by fire in prisons are reported, faster response times to incidents are required. So now there is demand to develop solutions and design configurations that offer this level of protection, as well as minimising false and nuisance alarms.
It is for that reason that Gent took an existing product, its S-Quad dual angle optical heat with CO sensor, and developed its application to this environment. The detector helps eliminate false alarms, as it has multi-criteria sensing techniques that, when combined, will provide accurate fire detection. The sensing device also provides sounder, strobe and voice alerts addressable to the individual cell in which it is installed.
In the presence of representatives from the Home Office, the S-Quad was tested inside an individual prison cell ventilation duct. In the installation, the airflow in the duct was measured at between 0.5 to 1 metres per second. The sensor was mounted in a position where it was in the direct line of airflow within the duct.
A number of fire tests were carried out which reflect typical risks within a cell environment, including: a smouldering cotton towel; smouldering clothing; fast burning paper and smouldering paper; and passive and active cigarette smoke.
The results demonstrated that the sensor positioned in the duct detected all of the fire types tested, and identified in which cell they occurred. The time took to recognise a real fire risk was within acceptable limits set by the prison authorities. Add to this the effectiveness of the sensor at ignoring the cigarette smoke for a period of time, and the solution was seen to be successful at meeting the Home Office needs.
Specifically, the reaction to cigarette smoke was observed to be reasonably low and while both the active and passive tests ended in a fire condition, the time taken was considerably longer than would be expected with other types of sensor. Minor configuration changes to the sensor could make further improvements to the immunity of the sensor to cigarette smoke and further long term testing is required to identify these. If the changes to the sensor are substantiated, then the S-Quad can be modified while in its installed position.
Gent has also identified a method of monitoring the ventilation system, using the input module built into every S-Quad sensor to monitor the airflow within each individual duct. This would offer the advantage of being able to detect if a prisoner has intentionally blocked the vent grill in order to reduce the system’s ability to detect fires, or indeed if there is a catastrophic failure of the vent system itself.
After the experiment, the general consensus from the Home Office was that the S-Quad would contribute towards improving the protection of life and property in UK prisons, by allowing the prison management to identify exactly where and when an actual fire occurs. The Home Office has now installed this solution in prisons within the UK.
In prisons more than in most environments, a balance has to be struck between early and accurate detection and avoiding false alarms. Simon Foulkes product manager at Gent by Honeywell, reports on a series of Home Office monitored tests.
In almost all cases it can be assumed that protection against fire is something that the occupants of the buildings want. But there are situations where intentionally defeating a fire protection system is often the aim of those in the environment. Even worse is the situation where occupants are determined to cause themselves self-harm and have, in some instances, elected to do this by means of fire.
In prisons, these situations need to be considered, with the additional risk that inmates may even want to start and use a fire to a cause a disturbance, or even facilitate an escape attempt.
In order to create an effective fire protection system in prisons and provide individual cell-by-cell protection, manufacturers need to think beyond the basic point source detector, traditionally sited in living and sleeping accommodation. The current, most common solution is to use duct detection, which simply involves a number of cells being protected by a detector sited in the plant duct which provides ventilation for a number of cell-blocks in that section. But the effectiveness of this approach will be limited by such factors as the distance from the cell to the detector – the further away the detector, the greater the reaction time.
In order to give the best possible protection to inmates, it is imperative that staff can locate the seat of the fire as quickly as possible, so cell identification is vital. This level of detail cannot be given from the duct detector solution, as the information provided will only relate to the whole block of cells served by the duct detector. Furthermore, the HVAC system may not continue to work in the event of power failure and so should, at the very least, be monitored by the fire detection system or have full standby capacity in accordance with the design.
Some have investigated the use of a standard point detector mounted behind a tough vandalproof protective mesh, to make it immune to all but the most determined malicious damage. But even if the prisoner isn’t able to damage the actual detector, malicious activation is still too easy. Add to this the risk of injury or death by ligature using the protective mesh in front of the detector and this solution becomes less attractive.
Home Office input
The Home Office has indicated that it needs detection systems to identify in which particular cell a fire has started. And as more incidents of self harm by fire in prisons are reported, faster response times to incidents are required. So now there is demand to develop solutions and design configurations that offer this level of protection, as well as minimising false and nuisance alarms.
It is for that reason that Gent took an existing product, its S-Quad dual angle optical heat with CO sensor, and developed its application to this environment. The detector helps eliminate false alarms, as it has multi-criteria sensing techniques that, when combined, will provide accurate fire detection. The sensing device also provides sounder, strobe and voice alerts addressable to the individual cell in which it is installed.
In the presence of representatives from the Home Office, the S-Quad was tested inside an individual prison cell ventilation duct. In the installation, the airflow in the duct was measured at between 0.5 to 1 metres per second. The sensor was mounted in a position where it was in the direct line of airflow within the duct.
A number of fire tests were carried out which reflect typical risks within a cell environment, including: a smouldering cotton towel; smouldering clothing; fast burning paper and smouldering paper; and passive and active cigarette smoke.
The results demonstrated that the sensor positioned in the duct detected all of the fire types tested, and identified in which cell they occurred. The time took to recognise a real fire risk was within acceptable limits set by the prison authorities. Add to this the effectiveness of the sensor at ignoring the cigarette smoke for a period of time, and the solution was seen to be successful at meeting the Home Office needs.
Specifically, the reaction to cigarette smoke was observed to be reasonably low and while both the active and passive tests ended in a fire condition, the time taken was considerably longer than would be expected with other types of sensor. Minor configuration changes to the sensor could make further improvements to the immunity of the sensor to cigarette smoke and further long term testing is required to identify these. If the changes to the sensor are substantiated, then the S-Quad can be modified while in its installed position.
Gent has also identified a method of monitoring the ventilation system, using the input module built into every S-Quad sensor to monitor the airflow within each individual duct. This would offer the advantage of being able to detect if a prisoner has intentionally blocked the vent grill in order to reduce the system’s ability to detect fires, or indeed if there is a catastrophic failure of the vent system itself.
After the experiment, the general consensus from the Home Office was that the S-Quad would contribute towards improving the protection of life and property in UK prisons, by allowing the prison management to identify exactly where and when an actual fire occurs. The Home Office has now installed this solution in prisons within the UK.
