• Subscribe to our monthly
  • Magazine
  • Newsletter
  • Digital Issue
  • Click Here

Detection, suppression and control

Joe Bush, Editor

04/10/2012

Tags: Safety in Engineering

Topics: Safety in Engineering

The application of heat can be an integral part of many production engineering and manufacturing processes, and therefore, fire prevention is a big issue. However, as Mike Fikuart of Industrial Design explains, each plant will have differing requirements and within each plant there are multiple applications that demand unique measures for detection, suppression and control

One of the things that every manufacturing or process plant has in common is that there is always a risk of fire and therefore, when dealing with the issue of fire prevention, the initial process is the same.

Information on the application must first be gathered - this involves discourse with the client, background research into the risk and normally, a site visit which will include viewing the process or equipment that needs protection, a demonstration and an explanation of its operation to identify any specific areas of risk.

Once this has been achieved it must then be decided where to put storage cylinders, pipe work and nozzles in order to get the optimum performance from the system whilst taking into account any restrictions caused by the equipment or processes. The customer’s production programme and shift patterns need to be factored in here to try and minimise any disruptive effect that the installation of the equipment may cause.

Legislation

There are compliance issues that must also be taken into consideration i.e. all systems should comply with current appropriate legislation (e.g. EN 15004, BS 5306 and BS 5839) unless otherwise agreed with the appropriate authority. This may further depend on the customer’s in-house regulations, site location and insurance company requirements.

Health and safety is a primary concern with all systems, both during the installation phase and during the ongoing use of the completed system.  Risk assessments and method statements need to be written, agreed and complied with during the installation phase and the system user must likewise adhere to agreed procedures during its ongoing use.

Industry differences

It’s here that the differences between each project and each sector begin to become clear. For instance, in the food and beverage industry, we often come across packaging machinery where they use heat-based shrink wrapping and carton sealing processes, which have been known to cause fires.

In these applications ultra violet or infrared detection would normally be used to provide a very rapid alert - required because of the quick burning process. The extinguishing system would probably be carbon dioxide applied using the local application method to extinguish the fire and cool the residue.

Another issue in food plants is deep fat frying, when problems can arise when oil is raised above its flash point or when ultra-heated product that has been immersed in oil for an extended period is exposed to the air. Here heat detectors can be used to detect the rise in temperature, and carbon dioxide for extinguishing. This suffocates the fire by preventing oxygen from supporting re-ignition as well as cooling the combustion source to below its spontaneous combustion level. As an alternative to carbon dioxide, water mist can also be used.

Another industry to consider is the tobacco sector. The process of preparing the tobacco, and also the process of making it into cigarettes and then packing and wrapping them in primary and secondary packing can create potential hazards. Polythene or cellophane packaging can result in problems similar to those found in the food industry.

Furthermore, fires caused by faulty electrical or mechanical equipment are possible in tobacco and packaging storage areas. Because the storage facilities can comprise large open areas with high, densely packed racks, high sensitivity aspirated smoke detection is often recommended for the early detection of a fire.

The automotive industry also creates a unique set of challenges. One example is the hazardous paint stores often found in a car plant. In many cases these areas are classed as hazardous because of the presence of stored solvents and other flammable liquids. These can require explosion-proof fire detection and alarm equipment. 

Another paint related hazard can be found in large electro-static spray painting booths, where the electro-static reaction can cause the paint to ignite as it’s sprayed out of the guns. Here the remedy is to use ultra-violet flame detection, which activates a discharge of carbon dioxide vapour through the paint spray lines, thus effectively blowing the fire out of the spray gun and extinguishing it in the same action.

Summary

One hazardous area that is common to all three industry sectors is the computer room. The risk here is normally of electrical fire, which requires point type smoke detection and an extinguishing system using an inert gas such as nitrogen or argon. However, these gases need large storage areas so if space is at a premium, the FM200 or Novec 1230 could be used. These are manufactured gases that require smaller extinguishing concentration and thus take up less storage space.

The essence of the problem is that where you have extreme heat there is the risk of fire. Nevertheless, by attending to the individual demands of each sector and, as in the examples we have discussed, the individual needs of the machines found in each industry, unique designs can be produced which share a common result - effective detection, suppression and control.

Related Articles