Particle board is a manufactured wood product. It is actually quite environmentally friendly, as it is built from compressed shredded wood scraps and recycled wood, held together with a type of resin. It is cheaper and more dense than hardwood, but is not very strong or resistant to moisture. It also does not take paint (let alone stain) well.
To combat these deficiencies, most particle boards are covered with veneers glued onto the exterior surfaces made to look like the desired hardwood. To the untrained eye, a piece of furniture made from veneered particle board looks like a fine hardwood piece.
There are some concerns that the resins used in the manufacturing of particle board may contain formaldehyde. This becomes a potential problem when cutting the particle board, as the saw blade tends to create very fine sawdust that you should avoid breathing. When cutting particle board, work in a very well ventilated area unless you have an extremely strong dust collection system.
Fires in particle board mills rarely lead to total losses, although the failure of the particle board press can certainly cause high losses (average of selected losses
While the chip dryer was frequently the source of losses in the Seventies and Eighties, the presses themselves were the primary cause in the Nineties.Because fire loads and potential ignition sources can come together at many points in this production flow, specifically coordinated fire protection measures must be taken. For example, one common ignition source is sparks produced by metal parts or stones rubbing against metal pipes. Other ignition sources include metal parts and ball bearings that have become hot, or overheated exhaust gases.
Apart from losses triggered by mechanical factors, a relatively large number of losses have been caused by leaks in the thermal oil system. Thermal oil is used to compress the chip cake and also to heat the cake so that the glue sets in the shortest possible time. The pressures applied are between 15 and 25 bar, while the temperatures are between 200° and 240°C, and thus sometimes above the flash point of the oil. The material ignites immediately in the event of a leak. Even if it does not ignite immediately, the oil can still catch fire on hot parts or due to biochemical reactions with the chips.
Generally the particle board manufacturing involves storage of huge quantities of raw wood or other raw material stock. Some times these are stored in the open. Unless house keeping is of a high standard, there is high possibility of ignition and fire. Due to the sheer fire load, it becomes very difficult to control the fire.
At the start of the production, the process could be wet involving water, but as the process progresses, the quantity of moisture in the board goes on decreasing whereby it reaches a stage where the material could be ready for combustion. In the finished goods area, there could be significant amount of hardboard storage resulting in extremely high fire loads. Since the boards are made in large sizes and are stacked up, shifting of stacks from the godown in the event of a fire is also difficult. Intense heat and smoke could hamper any loss minimization efforts. In such cases, control of fire becomes very difficult. Some factories that are located in remote areas with little access to public fire brigade are extremely vulnerable.
In some units, lamination of finished boards is done as an optional process. This involves application of printing solutions, glues and inks which could be potentially hazardous.
The following protective measures are taken to avoid the ignition sources and potential losses described above: Foreign-body separation, magnetic and by gravity, both lighter and heavier than wood, at all points where wood is delivered and chipped, Spark detection on all potential sources, such as fans, Spark removal or extinguishing,Pressure relief openings at all points where explosions can occur, such as in dry chip bins, chain conveyors and driers. Temperature monitoring of all moving parts (bearings), Special procedures for monitoring stages of production in which overheating can occur in the event of a power failure, e.g. emptying of a dryer by means of an emergency power supply.
The following extinguishing systems are obligatory
Full-area sprinkler system in production and in the storage areas, Deluge installations on the press, "microdrop" or conventional. Microdrop installations are particularly advantageous, because the fine drops or spray can absorb great amounts of heat very quickly. They are triggered manually or by heat sensors in the press after the alarm. The fire-extinguishing system also covers the inlet and outlet (saw) directly at the front and back of the press. The coupling of the thermal oil supply and the fire alarm system is very important in the particle board industry. If an alarm is triggered, the supply of thermal oil must be interrupted immediately to prevent additional oil from being poured on the fire.Thermal oil is combustible and is usually used at temperatures above the flash point in the particle board industry.
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