Shutdown alarm

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. 

MINIMUM DISPLAY ON LOCAL PANEL MINIMUM NO. ALARMS AND SHUTDOWN ALARM SHUTDOWN... 

These are instrument system loops that are necessary to avoid a failure which could result in nonreportable environmental releases, equipment or production losses, or reduced economic life, plus all other systems and alarms that assist operations that require prooftesting. These alarms and shutdown systems include refrigeration units that have less impact or safety or environmental issues than the Class 2 units, important pump shutdown alarms, low pressure utility alarms (well water, cooling tower water, natural gas, instrument air, nitrogen), and numerous low-pressure lubrication alarms. 

Alarms and shutdowns are necessary to prevent damage to RO and pretreatment equipment and to personnel near the unit. Common shutdown alarms are listed below ... 

Low reject flow—the recovery of the RO system is too high this shutdown alarm also protects against completely closing the reject flow control valve, which could damage the membranes. 

A pair of "N.O." contacts shall be provided, by vendor, for purchasers shutdown alarm to be activated only when the system malfunctions. 

SIF response to diagnostic faults (automatic shutdown, alarm only or other)... 

All shutdown alarms Total run time RO operating mode Recovery Influent flow Reject flow Permeate flow Pump status Valve status o Influent o Reject... 

Safety interlock systems should have pre-shutdown alarms to warn that a trip is impending. This enables the operator to take corrective action if time permits before the shutdown actually occurs. 

Shutdown alarm This type of alarm tells the operator that an automatic shutdown event has been reached and has been initiated by the SIS. It is basically a monitoring fionction for the SIS and confributes as a layer of protection because it supports corrective and subsequent actions by the operator. 

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