Alarm indications

Raising the alarm, including the location of alarm call points, internal fire alarm telephones and alarm indicator panels... 

Melder, m. announcer, informer alarm indicator messenger. 

Where this can be done, moving the alarm-indicating arms to the room condition will indicate whether the alarms operate but much more satisfactory results are obtained by causing the controlled condition to swing beyond the alarm points and at the rate that would be expected in practice. 

Consider again the alarm indicator and emergency shutdown system of Example 11-2. Draw a fault tree for this system. 

The top event is written at the top of the fault tree and is indicated as the top event (see Figure 11-14). Two events must occur for overpressuring failure of the alarm indicator and failure of the emergency shutdown system. These events must occur together so they must be connected by an AND function. The alarm indicator can fail by a failure of either pressure switch 1 or the alarm indicator light. These must be connected by OR functions. The emergency shutdown system can fail by a failure of either pressure switch 2 or the solenoid valve. These must also be connected by an OR function. The complete fault tree is shown in Figure 11-14. 

Alarms should be displayed on a conventional dedicated window annuciator panel or if control room based on a dedicated CRT display for fire and gas detection systems. Each detector location should be highlighted with indications for trouble, alarm low, and alarm high. Where annuciator panel window alarms the alarm indication lights should be provided with specific labels indicating the exact alarm locations. 

Panel alarms and indications should not be mounted lower than approximately 0.76 meters (2 6" ft,) or higher than 1.83 meters (6 0 ft ). Outside these limits the alarm s alarm indicators are less noticeable and awkward for maintenance personnel activities. 

Any process alarm that is associated with a critical instrument. This includes process alarms indicating an approach to a COP never-exceed-limit as identified in SOP s. 

A]t the time of the accident, roughly seven times the normal amount of butadiene had inadvertently been added to the reactor. Alarms indicated that the reactor had been overcharged, but interlocks were manually overridden to initiate the transfer of raw materials into the reactor vessel, contrary to established procedures.121... 

It seans that the source for expressing the existence of a relationship between SRB numbers and the severity of corrosion in soil is a paper by Ronay et al. in 1987, according to which if the number of SRB per gram is less than 5 x 10 , there is no risk of MIC, whereas a count of 10 or more SRB per gram of soil is alarming, indicating a severe case of MIC. 

FIG. 3. Self-induced vibrations of the leakage drain tankfloat (indications of the Signal alarm indicator). 

Local alarm indicating dangerous concentration in the building... 

The main features of the control system of the plant are reported here. A dedicated programmable logic controller (PLC) handles both regulation loops and an alarms-interlocks system. If any process condition exceeds the design values, a trip system is activated and an interlock sequence restores a safe state. The control panel operator monitors alarm indicators and may take appropriate action when needed to avoid a plant shut-down. 

Lead change commands Alarms indication (type, color, sound)... 

Operator Interface—Apply Human Engineering criteria (Ergonomics) to the design of the operator interface. Except on the smallest systems, message board type status and alarm indicators are preferred to an array of indicator lights and associated nameplates. 

Audio and visual alarm indicators. Can be upgraded to detect new compounds. Consumables include occasional filter and desiccant cartridge replacements. Meets military specifications, and Is currently used in the field by the U.S. military. 

Audio and visual alarm Indicators. Can be upgraded to detect new compounds through changeable data libraries. Capable of storing 50 libraries of 60 gas classes each. No consumables except for occasional filter changes. Can be used as a CWA or TIC detector. Has data logging capability and is capable of networking. 

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