Processing facilities alarm levels

As mentioned earlier, the process facilities have been designed to operate in environmental conditions based on a 1-year storm condition. During the 2 years that have elapsed, several bad weather periods have been experienced during which significant wave heights of 21 ft [6.S ml have been observed. It has been established that the worst environmental conditions encountered so far do cause liquid movement in the separators but have not adversely affected (he functioning of the process and utility systems and do not cause level alarms or shutdowns. 

The alarm levels for deployed ACAMS monitors at various facility sites are typically set at 20 percent of a specific airborne exposure limit or process control level. Thus, the absence of an ACAMS monitor alarm may be assumed to indicate that no agent concentrations of more than 20 percent of the airborne exposure limit have persisted for longer than the cycle period ( 3 to 8 minutes). The Army has set exposure limits and process controls at the levels mandated (in permits) for current disposal facility operations (U.S. Army, 1997a). These are reprinted in Table 2-2. The... 

Fire alarm bells or horns should be located in all buildings and on all levels of process structures and other open areas in sufficient number to ensure that all parts of the facility are alerted. Areas with high noise levels should have alarms with a sufficient sound level to overcome ambient noise otherwise, revolving beacons or strobe lights should be used in high noise areas. 

Some facilities have operations alarms that do not have an explicit safety purpose. For example, an operator may be preparing a solution of polymerization inhibitor. The recipe for this may change from batch to batch. If the tank for a particular batch is to be filled to say the 65% level, the operator can set the alarm at that value, start filhng the tank and then move on to some other activity. When the alarm sounds, he or she will stop the fill process. If the next batch requires a 75% level, the operator can adjust the alarm correspondingly. 

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