Safety alarms

Alarms with defined operator response Critical alarms Safety instrumented systems Pressure relief devices Blast walls and dikes Deluge systems Flare systems... 

Sufficient warning alarms, safety devices, and interconnections must be incorporated. 

Warning alarms, safety devices, and interconnections are in working order. No such device has been bypassed to keep the plant working. 

Sufficient warning alarms, safety devices, and interconnections must be incorporated and vendor shall demonstrate satisfactory working of all such systems prior to handing over the plant to purchaser. 

Keywords uniform approach, risk communication standards, alarms, safety and security aspects, human-machine interaction. 

Create a cross-disciplinary team that includes representation from clinicians, clinical engineering, information technology, and risk management, to address alarm safety. 

Why has alarm safety become an important patient safety issue ... 

PREVENTION (c) Safety-critical process alarms Safety Instrumented systems... 

Detection of Bromine Vapor. Bromine vapor in air can be monitored by using an oxidant monitor instmment that sounds an alarm when a certain level is reached. An oxidant monitor operates on an amperometric principle. The bromine oxidizes potassium iodide in solution, producing an electrical output by depolarizing one sensor electrode. Detector tubes, usefiil for determining the level of respiratory protection required, contain (9-toluidine that produces a yellow-orange stain when reacted with bromine. These tubes and sample pumps are available through safety supply companies (54). The usefiil concentration range is 0.2—30 ppm. 

Unless some discipline is imposed, engineering personnel, especially where contractors are involved, will define far more alarms than plant operations require. This situation may be addressed by simply setting the alarm hmits to values such that the alarms never occur. However, changes in alarms and alarm hmits are changes from the perspec tive of the Process Safety Management regulations. It is prudent to impose the necessary discipline to avoid an excessive number of alarms. Potential guidelines are as follows ... 

Improved sensors allow computer monitoring of the system for safety and protection of the equipment from damage. Sensors include lubrication-flow monitors and alarms, bearing-temperature sensors, belt scales, rotation sensors, and proximity sensors to detect ore level under the crusher. The latter prevent jamming of the output with too high an ore level, and protect the conveyor from impact of lumps with too low an ore level. Motion detectors assure that the conveyor is moving. Control applied to crusher systems including conveyors can facilitate use of mobile crushers in quarries and mines, since these can be controlled remotely by computer with reduced labor. 

Alarms should act as early warning devices to anticipate a potentially hazardous situation. Alarms that are essential to safety should be identified and classified separately from process alarms. Redundancy may be required. 

Provide critical alarms and safety systems independent of BPCS... 

Annunciation control (for low pressure alarm, high pressure alarm and operation ot the safety valve etc.)... 

Safety systems are typically divided into emergency trip/shutdown functions, controlled (slow) shutdown, alarm activation, or startup annunciation of auxiliary equipment such as oil pumps. 

The reservoir may be either pressurized or atmospherie. It must have suffieient eapaeity to eontain all oil during drain-baek or shutdown. It must be equipped with an oil level indieator, a low-level alarm switeh, safety relief valve, a pump for oil makeup during operation, drain valve, heater, mist eliminator, strainers, and required valves. Expander reservoirs must be designed and eonstrueted in aeeordanee with applieable ASME eodes. Reservoir retention time is typieally between 5-18 min depending on turboexpander size and manufaeturer s sizing eriteria. This is an area where the owner/purehaser should ask for the manufaeturer s assistanee. 

Note Alarms and shutdowns as shown are not to be considered as meeting any minimum safety requirement but are shown as representative of types used for controi systems. Schematic Alarm/Shutdown Hydrocarbon Low Pressure Hot oil or Glycol Amine Label Description Line Heater Reboiler Steam Heater Salt Heater Reboiler Reboiler ... 

The integrity of pipelines depends upon conect design, including materials selection, support and protection from mechanical damage. Depending upon tlie gas, routine inspection and maintenance may be supplemented by the provision of gas detection and alarm systems. Other considerations are exemplified by the safety-related controls on the transportation of domestic gas via pipeline systems summarized in Table 15.17. 

Cover means of communicating health and safety information m all workplaces. Include illuminated signs, alarms, verbal communication, fire safety signs, marking of pipework, etc. 

There are few chemical plants that are so forgiving that a control system or a safety interlock system is not required. Process engineers provide controls to assure product yield and quality and maintain safe operating conditions. This type of control system is a BPCS. The BPCS acts to alarm and moderate a high or low operating condition specified by the normal operating limits within the never exceed critical limits. The SIS is provided to shut down or otherwise place the process in a safe state if the BPCS fails to maintain safe operating conditions. A BPCS should not be used as the sole source of a process safety shutdown. 

Humans require time to react to process alarms and control requirements. Reaction time must always be considered early in the plant design. It is inherently safer to decide early in process design what administrative controls the operator will be assigned to activate for safety control. Requiring periodic operator interface to the process system relieves boredom and heightens interest in knowing the current condition of the process. See Sections 6.4 and 6.5. 

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