UB/SF

The PROTEGO® UB/SF diaphragm valve is the only deflagration-proof and endurance burning-proof valve of its kind in the world. It is a highly developed combined pressure and vacuum valve with dynamic and static Flame Arrester. It is primarily used as a device for flame transmission-proof in-breathing and out-breathing on tanks, containers, and process equipment. The valve provides reliable protection against overpressure and vacuum, prevents the in-breathing of air and product losses almost up to the set pressure, and protects against atmospheric deflagration and endurance burning if stabilized burning occurs.

When the pressure in the tank reaches the set pressure, the diaphragm (1) on the outer valve seat 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 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 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.