Alarms and Shutdown Systems

• Shutdowns and interlocks. Automatic shutdown and interlock systems (see Section 1200) prevent the startup of equipment or portions of the plant when operation would be a serious hazard. Alarms may be anticipatory or activated at the time of shutdown, and are displayed on the central control room alarm system
• Alarm and safety setpoints. Setpoints for alarms and safety trips should be recorded on the P&ID if they require setting in the field
• Low flow shutdowns in high energy systems. When a centrifugal pump is injecting liquid into a high energy system, shutdown of the pump can cause disastrous reverse rotation if the check valve fails to hold. In such cases, a low flow reading on the feed meter should close a control valve to prevent the backflow
• Computer communication. The process computer (if used) should monitor alarm and shutdown status