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Self-bunded tanks storing volatile liquids (e.g., fuels, solvents) require vacuum protection to prevent tank collapse during fluid withdrawal or temperature drops. The system balances internal pressure to maintain structural integrity. Here’s how it operates:
1. Vacuum Relief Valve (Primary Protection)
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Mechanical Operation: A spring-loaded valve opens at a preset vacuum pressure (typically -0.2 to -0.5 psi) to admit ambient air.
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Location: Installed on the tank roof or vent line to bypass normal venting restrictions.
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Fail-Safe Design: Reseals automatically when pressure normalizes.
2. Pressure/Vacuum Vent (Combined Protection)
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Dual-Function: Manages both overpressure and vacuum risks:
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Vacuum Scenario: Opens to allow air inflow during liquid pumping or cold contraction.
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Pressure Scenario: Releases vapors if tank overheats or is overfilled.
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Flame Arrestor Option: Integrated in hazardous areas to prevent ignition.
3. Vacuum Breaker (Emergency Backup)
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Non-Mechanical Solution: A weighted pallet or diaphragm that physically drops open under extreme vacuum, creating an air inlet.
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Used When: Valves fail or for high-flow withdrawal (e.g., tanker truck unloading).
4. Smart Monitoring (Advanced Systems)
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Sensors: Detect real-time pressure drops and trigger alarms or automated air intake systems.
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IoT Integration: Logs data for predictive maintenance.|
