In industries like chemicals, petrochemicals, and storage, ensuring the safety of storage tanks is a critical and complex task. Among various safety measures, pressure alarm systems play a foundational and essential role. Like a “warning system” for the tank, these alarms trigger immediate alerts when internal pressure rises abnormally, allowing operators to take action and prevent further escalation of risks.
Why Do Storage Tanks Need Pressure Alarms?
Throughout operation, storage tanks are influenced by multiple factors such as temperature fluctuations, material input and output, and exothermic reactions. If the tank pressure exceeds the design limits, it can lead to equipment damage, pipe leakage, or even catastrophic events like explosions or fires. Therefore, implementing an appropriate pressure alarm system is the final line of defense to ensure the safety of both equipment and personnel.
Pressure Alarm Level Settings
According to industry standards and safety management requirements, pressure-type storage tanks must have at least two levels of high-pressure alarms. This staged approach allows operators to be warned of risks at different levels and avoids the sudden escalation of pressure.
Level 1 High-Pressure Alarm
The threshold for the first level of alarm should be set to the upper limit of the normal working pressure. When the tank reaches this pressure, the system will send out an early warning signal. This alerts the operator to check the process conditions (e.g., temperature, feed rate, valve status) and make necessary adjustments to prevent further pressure increases.
Level 2 High-Pressure Alarm
The second alarm level should be set higher and is intended to signal a critical overpressure risk. The threshold for this alarm is typically calculated as the lower value between the following two formulas:
50% of the sum of the normal working pressure upper limit and the safety valve set pressure.
90% of the safety valve set pressure.
Simply put, this alarm acts as a “danger zone” warning. When triggered, it indicates the tank is nearing the safety valve’s activation range, and immediate emergency measures should be taken.
Why Are Two Alarm Levels Important?
Early Warning and Response Time: The first-level alarm gives operators time to address the issue before it escalates.
Enhanced Protection: The second alarm helps avoid frequent activation of the safety valve, a passive protection device that should not be frequently triggered. By having a staged alarm system, active control and passive protection can be effectively combined.
Automation Integration: Modern control systems can link the second-level alarm to emergency shutdowns, isolation, or other protective actions, ensuring a comprehensive safety response.
The Importance of Proper Configuration and Regular Maintenance
In practice, alarm threshold settings should be based on equipment design parameters, process characteristics, and operational experience. Additionally, regular calibration and testing are crucial. Malfunctions, false alarms, or delayed responses are often the key factors contributing to the spread of accidents.
Conclusion
Pressure alarms are not merely instrument settings but form a critical part of a systematic safety management approach. Properly configured alarm levels, timely responses, and comprehensive maintenance programs can effectively prevent overpressure incidents in storage tanks, thereby building a strong safety barrier for industrial operations.