Vacuum relief unit with means preventing the effects of an accident

Abstract

The invention relates to a vacuum relief unit for pressure equalisation between the ambient atmosphere and a tank in a tanker, wherein the vacuum relief unit comprises: a valve housing ( 10 ) with a first opening ( 12 ), whereby the valve housing ( 10 ) is able to communicate with the tank, and a second opening ( 24 ) with a seat ( 30 ) for a valve body ( 40 ) that is configured for being conveyable into the valve housing ( 10 ) to permit inflow of air to the tank; and a mechanism ( 100 ) configured for being able to prevent passage of seawater through the valve housing ( 10 ) in case of an accident, wherein the tanker is at least partially immersed into seawater, which mechansim ( 100 ) features a first movable part ( 160 ) that is arranged outside the valve housing ( 10 ) and whose movement can be controlled by the liquid pressure of the sea water, a second movable part ( 150 ) that can be advanced within the valve housing ( 10 ) and that is movably coupled to the first movable part ( 160 ). The invention is characterised in that the second movable part ( 150 ) is configured for being conveyable to abut on the valve body ( 40 ) by an increasing movement of the first movable part ( 160 ) to cause the valve body ( 40 ) to return to its abutment on the seat ( 30 ).

1 . A vacuum relief unit for pressure equalisation between the ambient atmosphere and a tank in a tanker, wherein the vacuum relief unit comprises: 
 a valve housing ( 10 ) with a first opening ( 12 ), whereby the valve housing ( 10 ) is able to communicate with the tank, and a second opening ( 24 ) with a seat ( 30 ) for a valve body ( 40 ) that is configured for being conveyable into the valve housing ( 10 ) to permit inflow of air to the tank; and    a mechanism ( 100 ) configured for being able to prevent passage of seawater through the valve housing ( 10 ) in case of an accident, wherein the tanker is at least partially immersed into seawater, which mechanism ( 100 ) features 
 a first movable part ( 160 ) that is arranged outside the valve housing ( 10 ) and whose movement can be controlled by the liquid pressure of the sea water,  
 a second movable part ( 150 ) that can be advanced within the valve housing ( 10 ) and that is movably coupled to the first movable part ( 160 ),  
 characterised in that the second movable part ( 150 ) is configured for being conveyable to abut on the valve body ( 40 ) by an increasing movement of the first movable part ( 160 ) to cause the valve body ( 40 ) to return to its abutment on the seat ( 30 ).  
   
     
     
         2 . A vacuum relief unit according to  claim 1 , characterised in 
 that the valve body ( 40 ) is configured for being conveyed essentially linearly into the valve housing ( 20 ); and    that the second movable part is configured for being conveyed linearly into the valve housing ( 20 ) opposite this direction.    
     
     
         3 . A vacuum relief unit according to  claim 1  or  2 , characterised in 
 that the valve housing ( 10 ) comprises a third opening ( 26 ); and  
 that the mechanism ( 100 ) comprises a housing ( 120 ) arranged in association with said opening ( 26 ).  
 
     
     
         4 . A vacuum relief unit according to the preceding claim, characterised in 
 that the first movable part ( 160 ) is a piston and that the second movable part ( 150 ) is a piston rod that is firmly connected to the piston ( 160 );    that the piston ( 160 ) and the housing ( 120 ) forms a sealed space ( 102 );    that the piston ( 160 ) has a surface that is configured for being able to be influenced directly by said liquid pressure; and    that the piston rod ( 150 ) can be advanced into the valve housing ( 10 ) through said opening ( 26 ).    
     
     
         5 . A vacuum relief unit according to the preceding claim, characterised in that the mechanism also comprises a spring ( 155 ) configured for providing a resistance to the movement of the piston ( 160 ).  
     
     
         6 . A vacuum relief unit according to  claim 4  or  5  characterised in that the housing ( 120 ) comprises a cover plate ( 130 ) provided with apertures ( 132 ), whereby the piston ( 160 ) can be influenced by said liquid pressure, and that the cover plate constitutes a limitation to the movement of the piston ( 160 ).  
     
     
         7 . A vacuum relief unit according to any one of claims  36 , characterised in that said third opening ( 26 ) is configured in a detachable wall portion ( 110 ) of the valve housing ( 20 ).