Alarm systems defined

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

Control System (BPCS), including functions of Supervisory Control and Data Acquisition (SCADA) system, the alarm system (AS) and Safety Instrumented Systems (SIS) performing defined Safety Instrumented Frmetions (SIF). Proper design of layers of protection is based on hazards analysis and risk assessment with consideration of human and organizational factors. It is essential to ensure required safety integrity level (SIL) for each of these layers. 

The next step after risk assessment of alarm system is to determine priorities for each signal defined taking into account the severity of consequences for personnel, equipment and plant in case of no reaction of the operator for hazardous event occurred and time available for reaction to prevent accident. 

Distracted alarm systems are systems in which supervisory tines can, but they do not have to be introduced direetly to the control and indicating equipment. Usually the eontrol and indieating equipment is there eonneeted to the transmission line to whieh are also eonneeted the elosely defined modules e.g. expanding modules, the modules of printers, the modules of the power. 

Major focus on an alarm system life cycle Similarity in life cycle development with lEC 61511 lEC 62682 developed based on this standard Performance indicators are very clearly defined Section on compliance... 

Dependable For alarm system to be dependable, alarm response procedure shall be well-defined, alarms should be rationalized (Clause 4.3), needs to have good HMI design, MOC handling, and performance alarm systems must be measureable and checks are made to ensure this is adequate. 

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 ... 

Management puts high profits above safety and tolerates excessive risk taking. That defines culture problems. Management decides not to replace the system, and begins a cost-cutting initiative that reduces the maintenance staff by one-third. The gas detection and alarm system continue to deteriorate, and maintenance staff cannot keep up with the frequent calls for repair and adjustment. 

PTC devices are available in a range of specifications to meet defined requirements in low voltage electronic circuits where they may, for example, protect automotive electronic circuits, cellular phones, laptop computers, loud speakers, power transformers, rechargeable battery packs, security and fire alarm systems and other products. 

Similarly, the Revisions to UFC Article 80 required that a continuous gas-detection system shall be provided to detect the presence of gas at or below the permissible exposure limit or ceiling limit. The detection system shall initiate a local alarm and transmit a signal to a constantly attended control station. The alarm shall be both visual and audible and shall be designed to provide warning both inside and outside of the storage area. The audible alarm shall be distinct from all other alarms. It defined a continuous gas detection system as a gas-detection system where the analytical instrument is maintained in continuous operation and sampling is performed without interruption. Analysis may be performed on a cyclical basis at a frequency not to exceed 30 minutes. P1... 

The programming of the fire alarm system by the fire alarm systems suppliers as defined by CFPS report and matrix (both 3rd version)... 

Within Section 2, we describe the basic concept of our novel model-based mutation debugging approach. Section 3 illustrates a model of a car alarm system, which is used as a running example during this paper. In Section 4 we define our deterministic Input/Output Timed Automata. In Section 5, we explain model mutation and a set of mutation operators for TA models and describe the linkage between model mutants and corresponding implementation faults. We explain our notion of the timed input/output conformance relation tioco and show the equivalence between language inclusion and tioco conformance in Section 6. 

The method of establishing and using alert/alarm limits varies depending on the particular vibration monitoring system that you select. Normally these systems will use either static or dynamic limits to monitor, trend and alarm measured vibration. We will not attempt to define the different dynamic methods of monitoring vibration severity in this book. We will however provide a guideline for the maximum limits that should be considered acceptable for most plant mechanical equipment. 

Hardware requirements — The system controller responsible for synchronizing the events is defined as LC System 1. It requires at least two time event outputs to trigger the injection of LC System 2 and start MS data collection. If MS fails, the injection of LC System 1 should be inhibited. Autosampler with ready-in, alarm-in, and stop inputs indicate capability to be stopped remotely. The autosampler of LC System 2 must be able to prepare a sample before the run from LC System 1 is finished and hold the sample in the injector loop until an injection signal is received. A manual injection input devices indicates that the autosampler can perform the required function. 

Where the need for fire detection is identified, the required performance of the fire detection system is already specified as part of the grading process. Fixed fire detection is typically installed to protect equipment that is high value, long lead time, or likely to be significant fire escalation hazards. The performance specification defines fire size and response time thresholds for alarm and action(s). Fire hazards are defined by radiant heat output (RHO). RHO gives a reasonable indication of the potential damage and the probability that the fire will escalate or cause loss. The RHO should not be used to determine fire thermal loading onto equipment and structures. Table 8-3 compares RHO and flame area for some typical hydrocarbon fires. 

Class 1 safety instrumentation loops include alarms and trips on storage tanks containing flammable or toxic liquids, devices to control high temperature and high pressure on exothermic-reaction vessels, and control mechanisms for low-flow, high-temperature fluids on fired heaters. Other Class 1 instruments include alarms that warn of flame failure on fired heaters, and vapor detectors for emergency valve isolation and sprinkler-system activation. All of these alarms, shutdown valves, and other critical instruments are regularly proof-tested to a well-defined schedule. 

Occasionally, there may be business pressures or maintenance scheduling problems that would encourage the delay of prooftesting of safety critical alarms and shutdown systems. Such situations can also delay of vessel inspections and safety relief valve testing. Some type of variance procedure or review policy should be defined to handle this occasional need. Such a policy ought to require the review of all of the inspection and test records on the specific equipment involved as well as an approval of the superintendent of the area. 

The top event of an event tree could be a release of a toxic gas from a relief valve. The team leader writes the top event on a flip chart. Each member of the multi-disciplined team to focus that event. Each of the second level events are defined and added to the detailed tree by repeatedly asking, Why did this event occur Because the system pressure rose. The question Why Because the alarm was ignored during a busy time. This continues until the true system causes are identified, such as the culture is to use shortcuts or not enough operators available for a difficult startup. [4]... 

A Safe Operating Procedure developed to create a uniform method to ensure that appropriate steps are taken prior to bypassing or removing an alarm, instrument, or shutdown system IWim service is described in the section that follows. This procedure can provide an effective way of communicating the status of an impaired instrument. The procedure has been in use for over five years. It assumes that all instrumentation has been classified into three safety critical systems. [7] (These classes have been defined in Chapter 9, but are repeated here.)... 

The data are plotted on a control chart in time sequence. This enables the analyst to readily observe changes in the measured value. The analyst can define warning and action limits on the chart to act as alarm bells when the system is going out of control. In Figure 4, it shows that all the results of the analysis of the QC samples are within the warning limits except for one result which is between the upper warning and upper action limit. 

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