Shelved alarm

EEMUA also recommends that for a control system with >1000 configured alarms should have standing alarm <10 and shelved alarm (other than maintenance shelved alarms) <30. 

What is standing alarm And what are shelved alarms ... 

Stale alarm (also see Table IX/4.1.2-1) When an alarm goes in to alarm state but never return to normal state within 24 h time. This is similar to standing alarm. Shelved alarm is an alarm resulted on account of alarm suppression technique/ mechanism initiated by operator to temporarily suppress a set of alarms until an underlying problem can be corrected. Shelved alarms must be presented to the operator. (Such shelving should be done with due authorization for with detailed reasoning noted and displayed. A review of the same after change of shift should be undertaken). When equipment is under maintenance alarms associated with it may be shelved. 

Average alarm rate in steady operation Alarms in 10 minutes after plant upset Average number of standing alarms Average number of shelved alarms... 

Establishing measures to keep the samples safe and guaranteeing their integrity (i.e., locks in shelves, temperature alarms)... 

C. (104° F.) should not be exceeded, and thermometers should be placed in the nitro-cotton, and the temperature frequently observed. An electric alarm thermometer is also a useful adjunct to the cotton drying house. Great care must also be taken that there are no exposed hot-water pipes or stoves in the drying house, as the fine gun-cotton dust produced by the turning or moving of the material upon the shelves would settle upon such pipes or stoves, and becoming hot, would be very sensitive to the least friction. The floor also should be covered with linoleum or indiarubber. When hot currents of air are made to pass over the surface of gun-cotton, the gun-cotton becomes electrified. It is important, therefore, to provide some means to carry it away. Mr W.F. Reid, F.I.C., was the first to use metal frames, carriers, and sieves, upon which is secured the cloth holding the gun-cotton, and to earth them. 

Shelving, suppression of alarm by operator wUl also cause non-appearance of alarm... 

Auditable Testing, classification, and prioritization of alarm and performance measurements are major issues related to this point. Each alarm is checked against its becoming stale, standing shelved, etc. needs to be considered. 

Shelving This alarm suppression technique/mechanism used by an operator to manually suppress an alarm temporarily during operation process for a definite... 

Standing alarms exist while the condition persists these are sometimes referred to as raised alarms. Shelving is a facility that allows the operator to temporarily prevent an alarm from being displayed when it is becoming a nuisance. The EEMUA guide indicates that during normal operations alarm rates should be less than one alarm every 10 minutes. A survey of 37 unique operator consoles in the petrochemical industry revealed that one third of the surveyed consoles were able to achieve this alarm rate. An additional one quarter of the surveyed consoles were found to... 

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