A fire shutter is designed to only be operated during fire conditions. Therefore, they are often discreetly hidden within a building and will only operate when required. There are quite a few different types of fire shutters available depending on the application and integrity rating required. But, how do fire shutters work exactly?
A standard tubular motor fire shutter will operate upon receiving a volt-free signal from the fire alarm system, once triggered the shutter will either ‘open’ or ‘close’ as intended. A conventional inline fire shutter can also be utilised for more industrial applications. Not only can they be activated by the alarm system, but also can trigger the auto-solenoid release mechanism, which would result in a controlled gravitational descent. A fire shutter can also be equipped with a control panel, which can be programmed accordingly to allow options like a controlled descent, two-stage closing or only activating by a local heat detector. Depending on the control panel, they can also provide audio and visual warnings, which will notify those in proximity to the fire shutter, which is activated and operating.
The reason companies may require fire shutters within their commercial or domestic premises is to limit the damage that can be caused by a fire. Thankfully, over the past five years, the total number of fires in commercial and industrial buildings in England has reduced. The latest fire statistics show that 14,308 non-dwelling fires were attended by Fire and Rescue Services in England in 2019/2020 with 15,025 the previous year, and 16,026 in 2015/2016. This data implies that people are implementing better fire risk assessments, which is mandatory by the UK government. A fire shutter is designed to departmentalise a building and minimise the damage caused by the spread of a fire. Last year (2019/2020), the data collated showed that 15% of fires occurred within a building and managed to spread throughout the whole building – resulting in devastating consequences. Again, this is a decrease from the previous year’s findings of around 16%.
What are fire shutters?
Fire shutters have similar design to standard roller shutters. However, several alterations have been made to the design to ensure that the integrity of the fire shutter is not compromised under fire conditions. In the event of a fire, a fire shutter is designed to either ‘close’ and contain a fire, or alternatively, it is designed to fully ‘open’ and be utilised as an emergency exit.
Due to the server pressures which occur during a fire, a fire shutter has been designed to expand and continue to operate as intended. To ensure that the expansion occurs and the integrity of the fire shutter is retained, a manufacturer is legally required to have a specimen tested by a notified body. This is a compulsory requirement as per the Construction Product Regulations 2013.
Fire roller shutters can be activated by either the triggering of the fire alarm system or by a local heat/smoke detector. The type of activation required must be considered within the businesses risk assessments. However, the different options available can be discussed, simply contact one of our sales team members.
How are fires shutters activated?
In the event of a fire, how do fire shutters work then? First, a fire alarm system will trigger the operation, resulting in the following procedures:
1. All personnel within building will become aware of the fire alarm being triggered and will begin to evacuate the building or premises in accordance with the fire risk assessment.
2. All fire shutters will operated as planned, either by a delayed ‘closing’ or alternatively, ‘opening’ as required within the Fire Risk Assessment. This will then result in containing the spread of the fire as planned.
When the fire alarm is triggered, it will automatically send a volt-free signal to the fire shutter control panel. Upon receiving this signal, depending on the settings of the control panel, the fire shutter will either ‘open’ or ‘close’ respectively. A fire shutter can also be linked to a local smoke or heat detector, therefore the fire shutter will only be operated when these detectors are activated. The purpose of a local heat or smoke detector is to allow the fire shutter to remain open for as long as possible to allow the evacuation of the premises.
Conventional fire shutters can also be activated via the triggering of the thermal fusible link and auto solenoid release mechanism. The conventional inline fire shutter can be activated via the fire alarm signal or via a flame triggering the fusible link, if this is activated then a controlled descent will occur.
Main types of fire shutters
There are also three main types of fire shutters that work slightly differently in their activation.
1. Tubular motor fire shutter
- Designed to be smaller
- Ideal for applications limited by spacing
- A power down device – requires a battery backup or mains power supply to operate
- Supplied with a UPS-FDI panel, which can receive a volt-free signal from the fire alarm and close on signal
2. Gravity fail-safe tubular motor fire shutter
- Manufactured with the single phase motor internally fitted into the barrel
- Brake is electrically powered in the close position and upon a power failure or compromised electricals, the fire shutter will operate on a controlled gravity descent
- Offers an additional fail-safe as the door will still descend regardless of electrical power
- Can be manufactured to a smaller size
3. Inline fire shutter
- Utilised for larger applications
- Single or three phase motor which is externally fitted to the coil casing – chain driven motors
- No power required for these doors to activate in the event of a fire
- When the thermal fusible link unit is triggered, they drop via a controlled descent
What happens if there’s a power failure?
As part of the standard BS EN 16034, a fire shutter must have a built-in fail-safe in case of the event of a power failure. Therefore, the standard clearly states that ‘stored energy’ must be available and enable the operation of the fire shutter even in the event of power loss to the premises.
A tubular motor fire shutter, which operates on single-phase electrical supply, is therefore accompanied with uninterruptible power system (UPS). These are commonly referred to as a battery backup unit (BBU). This unit provides a backup power source when the mains power has been compromised or fails. A standard battery backup will last for an estimated maximum of 8 hours after the regular power source has failed, this is due to the control panel and motor continuously draining power whilst in standby. To provide an additional fail-safe, we can also offer the upgrade to a ‘sleep-mode’ battery which can offer up to 30 days of ‘stored energy’ and is much more reliable.
An inline fire shutter, particularly operating on three-phased electrical supply cannot always be equipped with a battery backup system. Therefore, this type of fire shutter relays on ‘stored energy’ in the form of a gravitational energy, which would descend when the thermal fusible link is triggered.
Gravity fail-safe fire shutters
The gravity fail-safe fire shutter is the ideal solution for a smaller application that requires a fire shutter to descend via either receiving the fire alarm signal, or by a controlled gravitational descent. SSS Industrial Doors Ltd additionally tested a gravity fail-safe motor at the WarringtonFire testing laboratory on the 7th July 2020.
In the event of a power or battery backup failure, or motor wire damage, a gravity fail-safe fire shutter will still operate. Its fail-safe motor will activate and deploy the fire shutter due to an internal closed electrically powered brake that releases upon a loss of signal. The controlled descent is steady, and the gravity fail-safe fire shutter will fully descend within approximately 30 seconds.
As you can see, no stone is left unturned when it comes to providing fully functional fire shutters, and safety is of utmost importance to us at SSS Industrial Doors. It can be a lot to take in when understanding how fire shutters work, but we can assure you that we’re proud experts with a passion for fire shutters.