UB/SF

The Pressure/vacuum relief valve Pressure/vacuum relief valve is an umbrella term that includes pressure or vacuum relief valve as well as pressure and vacuum relief valve. PROTEGO® UB/SF diaphragm Diaphragm A diaphragm is a thin layer of material, which has a large surface area. valve is the only deflagration Deflagration Explosion propagating at subsonic velocity (EN 1127-1:1997). -proof and endurance burning Endurance burning Stabilized burning for an unlimited time. -proof valve of its kind in the world. It is a highly developed combined pressure and vacuum Vacuum Vacuum is the pressure in an enclosed space that is lower than the ambient pressure. valve with dynamic and static Flame Arrester Flame arrester Device fitted to the opening of an enclosure, or to the connecting pipe work of a system of enclosures, and whose intended function is to allow flow but prevent the transmission of a flame. . It is primarily used as a device Device A device is a pipe component that influences the media flow by opening, closing, or partially shutting off the flow channel or by dividing or mixing the media flow. for flame transmission-proof Flame transmission-proof Characteristic of a device to avoid flashback. in-breathing and out-breathing on tanks, containers, and process equipment Equipment Machines, appliances, fixed or mobile devices, control parts and accessories, and warning and prevention systems, whether separate or combined, intended for the generation, transfer, storage, measurement, control, and conversion of energy, and for the processing of materials, which have their own potential source of ignition and may cause an explosion. . The valve provides reliable protection against overpressure Overpressure Overpressure refers to an increase in pressure in a system or vessel above the normal operating pressure. and vacuum, prevents the in-breathing of air and product Product Includes equipment, protective systems, devices, components and combinations of these. losses almost up to the set pressure Set pressure Set pressure is the gauge pressure at the device inlet at which the relief device is set to start opening under service conditions. , and protects against atmospheric deflagration and endurance burning if stabilized burning Stabilized burning Steady burning of a flame stabilized at, or close to the flame arrester element. occurs.

When the pressure in the tank reaches the set pressure, the diaphragm (1) on the outer valve seat Valve seat The valve seat is a component on which the valve pallet rests when the valve is closed. ring (2) is lifted and vapors are released into environment. The set pressure is adjusted by weight of the liquid load (water-glycol mixture) in the outer ring chamber (3). The overpressure chamber is equipped with an opening (4) to keep the pressure in balance. The opening is equipped with a FLAMEFILTER® to prevent flame transmission into the overpressure chamber. If a vacuum builds up in the tank, it is transferred to the vacuum chamber (5) (inner chamber) through pressure balancing tubes. If the set vacuum Set vacuum Internal negative gauge pressure at which a vacuum valve first opens. is reached, the atmospheric pressure lifts the diaphragm of the inner valve seat ring (6), resulting in ventilation of the tank. Both the overpressure and underpressure are adjusted via the filling level of the load liquid in the various chambers and can be checked by floating level indicators (7).

If the set pressure is exceeded, explosive gas/product vapor/air mixtures are released into the atmosphere. The speed at which these mixtures exit the annular gap between the diaphragm and the outer valve seat ring is considerably greater than the flame speed. If this mixture ignites, flashback Flashback Phenomenon occurring in a flammable mixture of air and gas when the local velocity of the combustible mixture becomes less than the flame velocity, causing the flame to travel back to the point of mixture. into the tank is prevented. If the mixture flow continues, the dynamic flame arresting feature prevents a flashback, even in the case of endurance burning. Even at relatively low flow rates, e.g., during thermal out-breathing, the gap formed by the volumetric flow is so narrow, that flames in the gap are extinguished and a flashback is prevented.