Fire protection for machinery

In today's digitally-controlled machining technology, human surveillance over processing is no longer foolproof .

Sparks can cause fire in machining equipment

Most cutting oils used become combustible at certain temperatures, and the formation of oil vapour also heightens the risk of combustibility. These oils only ignite if sufficient energy is applied. The risk of flaming may be due to an excessive rise in the temperature of the oil (spontaneous flaming), but flaming is most often caused by sparks that occur when there are fractures in the cutting tool.

We offer a simple method of quickly controlling fires that can start in this type of equipment.

Temperature and flame detection in machining equipment

The type of detection used largely depends on the process configuration.

• The risk of spontaneous flaming is generally eliminated by detecting the internal temperature of the machinery in the work area and by measuring oil temperatures.
• If flames are detected when localised in the work area, an alert can be activated when the fire is still in the incipient stage. UV flame detection is not recommended since UV radiation is absorbed in oil vapour. Detection through infrared radiation is the suggested method.
• As a rule, a manual detector is available.

Control and indication in machining equipment

A control and indication panel is positioned in the vicinity of the machinery. It manages the signals generated by the various detectors and controls the automatic extinction. It also controls the information devices (sound alarm, flashing lamp) and generates the interlocking contacts required to stop the process.

CO2 and water to extinguish a fire in machining equipment

Our installations are designed to control fires when they are in the incipient stage. Therefore, an extinguishing agent which has immediate action must be made readily available.

• CO2 is easy to use and is the only gas that can be used for localised protection. It acts primarily through its cooling action as well as by reducing oxygen content.
• Water in its various forms (spray or mist, for example) can also be used.

We carefully investigate the compatibility of the extinguishing agent with the surrounding objects.

The extinguishing system consists of steel pipes, hoses and spray nozzles.

CAUTION: When the protected area is in direct contact with the air surrounding the workshop, the fire extinction system must be designed so as to avoid flame projections. The reason is that some types of oil can rise to extremely high temperatures and set fire to objects in the surrounding area such as cables, plastics, cardboard, fabric, or other materials.

Immediate activation of the fire protection system

When flames are detected close to the fire risk in the machining area, the detectors send a signal to the indicating panel. The elements below are immediately triggered:

• Sound alarm and flashing light.
• The interlocking contacts in order to interrupt the process and particularly the blower.
• Extinction. The reservoir containing the extinguishing substance is equipped with a solenoid valve which opens immediately. As soon as flames are no longer detected by the sensors, this valve automatically closes. A single reservoir can therefore be used for multiple  extinction cycles. The reservoir level is checked continuously, and a shortage of the extinction substance is displayed on the indicator panel.