Deflagration suppression systems

Provide automatic sprinkler system/inerting gas Provide deflagration vents Provide deflagration suppression system Monitor flammable atmosphere/fire Provide nitrogen blocks (nitrogen injection to stop flame propagation) or other explosion isolation measures... 

It should be recognized that deflagration suppression systems have a number of shortcomings, such as ... 

Figure 3-12 is a schematic of a deflagration suppressant system for process equipment. Each application requires experimental validation of the suppression system design. 

Additional information on deflagration suppression systems can be found in NFPA 69 (1997), CCPS Guidelines (1993), Bartknecht (1989), Schofield and Abbott (1988), and Eckhoff (1997). 

FIGURE 3-12. Schematic of a deflagration suppression system for process equipment. 

This type of isolation device (also called a chemical barrier) is similar to deflagration suppression systems used on process equipment. This barrier system consists of an optical sensor, installed in the pipeline or duct between two items of equipment, that detects an oncoming deflagration... 

Chemical barriers are similar to deflagration suppression systems. Typically, optical sensors are installed in upstream locations of the pipeline in which the flame is to be stopped. Upon a detection of flame, the sensor sends a signal to the control unit, which amplifies the signal and triggers the detonator-controlled valve in a suppressant bottle. The extinguishing agent is injected into the pipeline through a suitable nozzle. Pressure... 

Deflagration pressure can be reduced substantially by suppression. Figure 26-30 shows the pressures measured in an ethylene-air explosion and a sodium bicarbonate-suppressed ethylene-air explosion. Fike Corporation, Blue Springs Missouri, and Fenwal Safety Systems, Marlborough, Mass., supply explosion suppression systems. 

Suppressant A chemical agent nsed in a deflagration snppressant system to extingnish the deflagration. 

A very careful study is required to develop a confidence for deflagration suppression in any flammable or dust system. The potential damage can be enormous. 

Explosion suppression and ultra-high-speed deluge systems (UHSD) act within milliseconds to extinguish an explosion or fire almost at its inception. The two techniques are quite different. Explosion suppression systems are designed to (1) confine and inhibit a primary explosion, (2) prevent a secondary and more serious deflagration or a detonation, and (3) keep equipment damage at a minimum. 

The operation of an explosion suppression system is a race against time. On the one hand, there is the buildup in pressure due to the explosion, and on the other, the counterplay is the detection of the explosion, application of the suppressants to extinguish the deflagration, and corrective action to limit the extent of damage. The operation of a typical system is illustrated in Figure 3.58. 

Is the product dusty or hazardous Even if the product is water wet, consideration should be given to the fact that the product may be toxic, flammable or hazardous in other ways. This would entail a hazard analysis review of what if situations. For example. What if the product escapes from the confinement of the dryer, or what if air gets into the dryer from the surrounding environment Some drying processes may require the addition of a fire or explosion suppression system. One such system uses an infra-red detector to sense a cinder combined with a sonic detection device to sense the shock wave of a deflagration. 

Explosion suppression is used for the protection of extremely hazardous systems in industry. Explosions that develop very high radial flame speeds (such as hydrogen-oxygen) are too fast for existing equipment. Many detonations (ultrasonic) also develop from an initial deflagration. It is possible... 

In [9] several examples for the simplification of systems are given. Among them are designs withstanding the maximum explosion pressure (Table 2.17 shows that 10 bar is a good choice in case of deflagrations). This saves the necessity of complicated measuring chains and active systems for explosion pressure suppression, which can fail as well. 

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