Explosion Prevention

The Explosion Pentagon
Five things necessary for a dust explosion to occur:
  1. Ignitable Dust
  2. Suspension of the dust into a cloud (in sufficient concentration)
  3. Confinement
  4. Oxidant (usually air)
  5. Ignition


If any one of these is missing there can be no explosion.

Infrared hot body detection is dedicated to finding and eliminating ignition sources.

The concept is simplicity itself:

Detect a hot body before it can ignite the dust, take fast action to remove the heat, or remove the hot body from the rest of the process product. The amount of energy required to ignite a specific dust is determined by test. Many dusts will ignite explosively at temperatures well below 500ºC. To understand the concept of true infrared, think of a lighted wooden match. Upon blowing it out the temperature of the smoldering head is about 500ºC. There is enough energy in the extinguished match head to initiate a dust explosion. If such a smoldering match head were to pass by a true infrared detector in a process convey line, for example, it would be detected. Taking an action to either eliminate or quench it would complete the protection scheme.

In every system there are high-risk zones where the possibility for a dust explosion is relatively high. Ignition sources exist in a variety of forms: Sparks and embers, hot surfaces, and static electricity to name a few. Frequently, the sources of ignition occur within the production equipment itself. For example, metal strikes metal, or by heat generated in the process, or by friction, or by loss of ground. High-risk equipment includes mills and grinders, ovens and dryers, rotating equipment bearings, dust collectors, storage bins and hoppers, or anywhere that a high concentration of dust may accumulate. It is also possible for worn parts or foreign objects such as nuts, bolts, or tramp metal to become sources for ignition with subsequent explosions. In order to prevent fires and explosions, therefore, a thorough knowledge of the process and components is essential. By analyzing the system, the ignition sources, and the sequence of events in the process, it is possible to design and install a protection system that will find trouble before it develops and take immediate action to prevent an explosion.

Unique technology, which in combination with our experience and understanding of process systems, addresses the ignition problem more effectively than was previously possible. Infrared hot body detectors can be used in ordinary light without triggering. The temperature limits of the detectors are low, typically 400º C, 250º C, or 175º C. These low temperatures, well below the almost 700º C threshold of spark detectors, make it possible to use this technology to prevent dust explosions. This is especially important for very ignition sensitive dusts. Older spark detection technology is not adequate in many circumstances involving today's high technology products and large-scale production requirements.

While it is true that high sensitivity can be critical for adequate warning and protection, all would be for nothing if the system could not distinguish a true threat from a nuisance. In other words, it would not be useful if the protection system were to trigger and interrupt production needlessly. Extraordinarily sophisticated controls ensure reliable detection without nuisance alarms. Based on the principles of movement and thermal mass, the instrumentation distinguishes a particle with high enough energy to ignite a dust explosion from sparks, which do not have enough mass to pose a credible threat. Moreover, our systems are not individual components sold in a patchwork fashion. Each system is designed from the ground up and is engineered to meet the specific requirements of the process system to be protected. Taking a total system approach, careful consideration is given to each aspect of the process system including location of detectors and reaction components, control panels, and integration with the main process control system.

Action components include water spray zones (deluge and misting), isolation valves (knife-gate, and pinch) CO2 flooding, and diverter valves. The fully integrated electronic control package allows over 50 parameters to be monitored and stored in an internal memory. The control package can also be connected to an ordinary PC using Windows which will allow an extended quantity of operating history, only limited by the capacity of the hard drive, to be stored. This provides a detailed record of detections, and allows the user to watch trends for each and every protected component in the process system. This record can even serve as a monitor of process component performance.



We are dedicated to keeping you running and manufacturing your products, while providing you with a level of safety not possible until now.



Copyright © 2006-2008. CV Technology. All Rights Reserved.

Text Only:  Dust Explosions ||  Explosion Protection ||  Explosion Prevention ||  Explosion Consulting