The inert gas system must have:
    
    
        
        (a) 
         At least one check valve in the cargo area to prevent the back flow of cargo vapor into the inert gas system, or another means specially approved by the Commandant (CG-522);
     
    
        
        (b) 
         If the inert gas system is in the machinery space or another space outside the cargo area, a second check valve in the cargo area meeting paragraph (a) of this section;
     
    
        
        (c) 
         Automatic and manual inert gas pressure controls; and
     
    
        
        (d) 
         Valves to isolate each inerted space.
     
    [CGD 74-289, 44 FR 26009, May 3, 1979, as amended by CGD 82-063b, 48 FR 4782, Feb. 3, 1983]