Gas BBQ catches fire and goes out of control

bbq-fireMr PC, in London, bought a 4kg UltraFire powder extinguisher from Safelincs back in 2011. He contacted us again a few days ago to tell us how he had used the extinguisher to successfully put out a dangerous BBQ fire. As Safelincs offers free ‘after the fire replacement’ he, of course, asked for his free replacement extinguisher which we have sent him. This service, exclusive to Safelincs, ensures that our customers never hesitate to use their fire fighting equipment and that they are protected again as quickly as possible.

Mr PC had started his almost new gas BBQ (it had only been used once before) at around 5pm and was entertaining his guests when later that night at around 11:30pm the flames of the fire went from ‘controlled’ to ‘uncontrolled’, as the fat at the base of the BBQ caught fire. The lid of the BBQ was immediately shut to starve the fire of oxygen, however, the opposite happened. Drawing air from the holes in the bottom of the BBQ the fire really heated up with flames licking out from underneath the lid.

The gas was turned off but the fat fire still continued. Mr PC evacuated his guests, then fetched his 4kg powder extinguisher from his house and extinguished the fire.

The heat of the fire had been so extensive that the mesh of the BBQ was deformed by the heat!

So, while gas fired BBQs have the advantage of exact control of the heat while everything works as expected, it is still wise to position a gas BBQ away from the house, ensure that fat cannot build up and to have some form of fire fighting means ready.

New BS5839-1:2013 fire alarm system standard explained

fire-alarm-panel-kits

The BS5839 part 1 :2013 standard  ‘Fire detection and fire alarm systems for buildings. Code of practice for design, installation, commissioning and maintenance of systems in non-domestic premises‘  is the key standard for commercial fire alarm systems with central control panel/s. It helps customers and installers to specify, design, install and maintain fire alarm systems.

It is a substantial document and to help our customers find their way through the standard we have created a summary of the standard. The summary covers:

  • Why might I need a fire detection/fire alarm system for my premises?
  • What are fire detection and fire alarm systems?
  • What is meant by ‘category of system’?
  • What are the main design considerations for an appropriate fire detection/fire alarm system?
  • What are the main installation issues?
  • What hapens once the installation is complete?
  • Commissioning, Documentation, Certification
  • Maintaining the system: what is involved?
  • User’s responsibilities and premises management: who does what?

Safelincs, the UK’s most progressive and customer friendly fire safety company offers its customers nationwide maintenance of fire alarm systems as well as a range of fire alarm system components:

For quotations for a new fire alarm system, please ring our friendly customer care team on 0800 612 6537

To arrange your fire alarm system maintenance visit, please ring 0800 612 4827

Gaps Underneath Fire Doors

We get often asked if gaps are allowed underneath fire doors and if so, how big they can be. We researched on your behalf and compiled this blog to explain the current recommendations.

The Basics

What happens in case of a fire? There is positive pressure in a room on fire (until the fire is vented) but at the base of the fire the pressure must be negative to draw in the air for the fire to receive oxygen. The smoke and the fire will try to push through the side and top gaps around a fire door while (usually) drawing air from underneath the door.

The Development of Fire Door Testing

The old test of fire doors to BS 476 Part 8 (for fire resistance) was carried out simply in a furnace increasing the temperature to that found in rooms on fire and the door was checked to ascertain when the fire would breach the door, usually at the gaps at the head and sides of the door. This was changed in the eighties to BS 476 part 22 which was similar, however, the furnace was now pressurised. Old BS 476 Part 8 fire doors failed this new test (usually after around 20 mins for a 30 minute FD30 fire door), so intumescent strips, also called fire door seals, were introduced to ensure fire doors passed the test. However, cold smoke can still seep through the gaps around the door and cause death from smoke inhalation. In some applications  therefore fire doors with cold smoke protection around the sides and top are required (recognisable by the ending ‘s‘, e.g. FD30s). This is usually achieved by installing fire door seals with integrated cold smoke brushes.

Fire doors tested in accordance with the cold smoke test requirement BS 476 part 31 ensure that in the early stages of a fire, the cold smoke does not percolate into escape routes and makes them impassable. At first the standard was only concerned with the gaps at the head and the sides of the door, as the air passing though the threshold gap to feed the fire keeps the smoke in the affected room. However, now the standards have changed and for fire doors requiring cold smoke control, the threshold gap does now have to be considered as well.

This is quite confusing, as fire fighters were always taught that at floor level there is a layer of an inch thickness of fresh air no matter how severe the fire is and if you get caught, get your nose on the floor to breathe. Consequently, the threshold gap was never considered important and BS 8214:1990 reflected this by stating a threshold gap of 6/8mm was acceptable.

Nevertheless, in BS 8214:2008 this changed and it states that under-door (threshold) gaps should be in accordance with the manufacturer’s installation instructions for the particular doorset design. When fitted, smoke seals should give an even contact with the floor but should not exhibit significant increased frictional forces that could interfere with the closing action of the door (see BS 5588-11). BS 5588-11 is now withdrawn and BS 9999 is the current standard. BS9999:2008 recommends for fire doors with cold smoke control that the threshold gap should be either less than 3mm in height or should be fitted with a threshold seal.

When speaking with manufacturers, however, a common statement is that a fire doors gap of up to 8 mm underneath the door is permissible. This is probably just referring to normal FD30 applications, as the fire door manufacturer is not involved in upgrading fire doors to cold seal protected standard (FD30s).

Conclusion

Ask your fire door manufacturer for their recommended threshold gap. If this information is not available it seems reasonable to permit a gap of up to 8mm for general fire doors (eg FD30). If you have a requirement for cold smoke control (eg FD30s) your threshold gap should be less than 3mm or you should fit a threshold smoke seal.

This advice applies for most applications, however, special requirements must be considered in a your fire risk assessment.

Wireless smoke alarms selection tool launched

wireless-system-selector-toolInterlinked smoke alarms notify residents of a building if a fire breaks out in a distant room, where there could be a risk of not hearing the smoke alarm. Here is an example: a fire starts in the kitchen at night while the occupants of the house are asleep in bed. The alarm in the kitchen detects the fire and starts beeping, this message is relayed to the interconnecting alarms throughout the building to alert all occupants and will also rouse them from their sleep, allowing for a safe escape from the fire. An interlinked system for such a scenario will consist of at least one heat alarm in the kitchen and a smoke alarm in the bedroom or on the landing.

There are different ways of interlinking smoke alarms, most of them involve cabling between each unit. Wireless smoke alarms, however, do not require a cable between each alarm; they pass the signal between the different detectors as a radio frequency signal. This way of passing a signal is accepted by British Standards as an alternative to wiring between alarms.

Wireless smoke alarms,have broadly speaking, four power supply options:

The mains powered alarms, while using RF (radio frequency) signals for the communication between themselves, have, of course, some wiring for the power supply. Each of these smoke alarms is supplied with power from either the nearest light fitting or a separate mains power supply circuit.

Mains powered wireless smoke alarms fully satisfy the standard BS5839-6:2013 Grade D, however the sealed ten year power supply of the Ei600TYCRF wireless fire alarm series is usually also accepted as Grade D alternative by Building Inspectors and fire safety officers. Please ask your Building Inspector or fire safety officer before installing the ten year Ei600TYCRF series if your building requires Grade D alarms.

Each of the above smoke alarm series include a range of different fire detection sensors, usually:

  • Ionisation smoke alarms – Detect the electrical property changes of the air in case of a fire
  • Optical (photoelectric) smoke alarms – ‘See’ smoke when it enters its detection chamber
  • Heat alarms – Detect the increase in temperature from a fire

Depending from the application and the room, a specific sensor type is necessary. This can be quite confusing if you are not an expert.

To aid in this selection process Safelincs has developed a website dedicated to explaining wireless smoke alarms. We have also created a system selector tool to help you pick the correct units for your building. Just select the power supply type, enter the number and type of rooms to be protected and the system will place the correct smoke alarms into your basket.

If you still have questions, please contact our friendly customer service on 0800 612 6537 and we are happy to help you.