Pressure Relief Valve - Emergency Relief Valve Function and Description The ER/V-F type PROTEGO® valve is a highly developed emergency pressure relief valve with high flow capacity. It is primarily used as a safety device for emergency pressure relief for storage tanks, containers, silos, and process engineering equipment; it offers reliable protection against overpressure and prevents impermissible product vapor loss close to the set pressure. It is designed to discharge particularly large amounts to prevent the vessel from rupturing in a emergency case. The spring-loading allows for higher set pressures than those with the ER/V or ER/VH.