Alarm systems philosophy

Alarms (Chapter 12)— This chapter presents an assessment of alarm systems. EEMUA 191 is a guide to the design, management, and procurement of alarm systems. It covers all aspects of human factors in the design of alarm systems for control centers, such as alarm system philosophy, key design principles, and key performance metrics. The approaches taken are... 

The alarm systems should have a philosophy that relates to the input data - number, types, degree of alarm, and displays and priorities. The information load on the operator has to be constantly taken into consideration, e.g., the distinction between alarms and status signals versus operator action that needs to be initiated. 

For brown field applications, there is likely to be a temptation to just copy what we had in terms of alarm philosophy while this may appear to make the design phase simpler, it is recommended that the strategy is reviewed considering the points above. One final key point with regard to alarm system design is to consider how to ensure that the plant does not routinely run with significant numbers of live alarms. 

The philosophy of fire protection is based fundamentally on the prevention of fire by choice of materials and by minimization of inventory of incendiary material. Once a fire occurs (going on in the scenario), the second measure is to prevent the spread of fire by the design of fire sectors and the use of fire-resistant barriers. Thirdly, one has to detect the fire, usually by means of a fire alarm system. Finally, no doubt, one needs organization, staff, and equipment for fire extinguishing by installed and mobile means. 

Detailed requirements for alarm philosophy document Alarm system requirements specification Alarm identification and rationalization Alarm and HMl design details with advanced methods Implementation, operation, and maintenance Monitoring and assessment Management of change handling and auditing Standard hence with lesser examples... 

Audit The audit stage is mainly meant for periodic review of the work processes and performance of the alarm system with a goal is to maintain the integrity of the alarm system throughout its lifecycle and to identify areas of improvement. Audit process may call for updating philosophy document to reflect any changes carried out during audit. 

From the table, it is quite clear how standard itself guides philosophy documents because it is very important for further system design on alarm systems. 

Alarm philosophy encompasses basic definitions, key work practices, and various processes as well as the alarm system performance goals and details about the, roles, and responsibilities. This facility specific document provides guidance for a consistent approach to alarm management and defined activities of the alarm management life cycle. Major positive issues (see Fig. IX/4.4.2-1 and Table IX/4.4 1), addressed by alarm philosophy shall include but are not limited to the following ... 

Philosophy of ITER Alarm System Management Iter 3WCD7T, February 01, 2013. http //static.iter.Org/codac/pcdh7/Folder%201/l l philosophy of ITER Alarm System ... 

Whatever method is used, there should be a clear design philosophy for the basic process control system (BPCS) employed at a facility that is consistent throughout each process and throughout the facility. Consistency in application will avoid human factor errors by operators. The philosophy should cover measurements, displays, alarms, control loops, protective systems, interlocks, special valves (e.g., PSV,... 

For preliminary CHAZOP the following documentations are necessary. Note that in most cases these are similar to what has been discussed for HAZOP. Basic flow sheet Basic equipment details MSDS and associated chemistry Proposed site layout with tanks Utilities and their location details Basic control philosophy Overall system architecture Alarm and trip schedule Safety and protection details Functional specification Linking with DCS/PLC Tentative 1/Os Interface points with types Environmental conditions... 

Physical and chemical property data Control philosophy Control system details Alarm and trip details Maintenance plan Operating conditions Plant layout details Plant location Applicable standards Legislative Risk details... 

FGS functionally performs a number of functions such as monitoring of fire, smoke, and/or sensing accumulation of gas. On detection generates alarms and initiates mitigating actions. It consists of sensors, logic solvers, and final elements to initiate mitigating actions. Additionally, it also interfaces with other systems in IPS and SIS. Within the system, it diagnoses the fault of sensors, etc., and at times inhibits the same or supports manual inhibition with alarm in each case. As stated earlier, philosophy documents lists out quantity of various types of FGS sensors at various locations in a tabular form with various facility areas as rows. The columns indicate various types of detectors such as ... 

Figure C-59 la a schematic diagram of the primary coolant temperature control system The use of the various basic components and the application of the general design philosophy is well illustrated in the diagram Summing point monitors are used to detect and alarm failure of all key amplifiers in the main control circuit (at the right of the figure) ...

Good practice checklists, discussion in an expert team and exploration of scenarios are centra elements. Check lists cover seven elements Organisation and management. Procedures, work descriptions and workload. Competence and training, Communication/distributed situational awareness, Working environment. Layout, and Control and safety systems. The checklists explores key human factors (safety) issues in each area, i.e. when discussing control systems the use of alarms is explored and a question is the existence of an alarm philosophy , and performance issues of alarm handling such as the acceptable number of alarms pr. hour. 

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