Fire Protection for Industrial Conveyor Systems
With thousands of roller conveyors in use in all kinds of industries around the world, Patol, the UK manufacturer of industrial fire detection systems and flame sensors, is advocating the installation of specialist fire protection above the conveyor systems. The day-to-day operation of many systems has the potential to transfer any fire from the belt into the whole processing plant - whatever the application.
Patol is an industry leader in the design and manufacture of specialist fire detection products for industrial applications and its Atex IECEx approved 5000 Series is a solution perfectly suited to this kind of application. Several models are available including specialist sensors with ATEX certification for hazardous dust environments and there are even glass-free, stainless steel sensors designed for use within food processing.
Many goods carried on conveyors - biomass; black and brown coal, industrial confetti (for Energy From Waste plants); recycling products; sulphur - are highly combustible and have the potential to self-ignite. If they should combust upon an unprotected belt, the likelihood is that the system will enable fire to spread into the holding hoppers, blending, crushing or other processing areas of the plant. As part of the operators’ risk management policies, the installation of early warning protection along a conveyor susceptible to conditions of excessive heat can avoid catastrophic fire damage and substantial consequential losses.
Patol products include a range of early warning infrared transit heat sensors designed to monitor and detect, in the presence of ambient light, ‘hot spots' and embers from combustible materials being transported on conveyor systems. The range of 5000 series sensors features a continuous air purging system to maintain an automatic cleaning system that prevents dust from settling on the lens of the sensor. Perfectly suited to hazardous and dusty environments, the sensors are typically mounted at 1 to 1.5 metres above the conveyors at an angle of approximately 30°. Initially sited five metres after the loading end of each conveyor system and thereafter roughly every 100 metres, sensors should also be located at transfer points and other inlets.
The sensors are aligned such that the monitored potential hazard passes through their field of view. Relays can be connected to stop the conveyor in the event of a fire occurring and a fire-extinguishing panel to operate a mist or sprinkler deluge system at the point of activation. Patol sensors provide outputs for Alarm/Trip and Fault monitoring.
A fire that occurs alongside the conveyor system or upon a stationery belt is also a potential threat. When the conveyor has been stopped either deliberately, or unintentionally by jammed rollers or bearing problems, any smouldering product could again cause significant damage. To provide protection against this possible problem, Patol’s Linear Heat Detection Cable (LHDC) should be installed either side of the conveyor using knock-on clips at every 1 metre roller frame brace and/or above using a catenary wire. Linear Heat Detection Cable is available as resettable and non-resettable technologies. The resettable cable, described as ‘analogue’, is designed to provide early detection of fire and overheating in circumstances where other forms of detection would not be viable - either because of its inability to sustain the environmental requirements or through prohibitive cost. Non-resettable or digital LHDC operates at fixed temperatures. A range of Alarm temperatures are available. The digital LHDC comprises of a twisted pair, two-core cable. Each core is a tinned copper coated spring steel conductor and has special heat reactive polymer insulation. The cable has a protective chemical and UV resistant outer jacket or sheath. Optional monitoring can be installed and consideration should be given to the additional mechanical protection to the cable provided by Patol's option of a stainless steel braided version. An LHDC system typically also includes an end-of-line termination box or an optional fire/fault test switch.