A system. The system includes a valve assembly. The valve assembly includes a first port, a second port fluidically couplable with the first port upon application of negative pressure at the first port, a third port fluidically couplable with the first port upon application of positive pressure at the first port, and a first check valve positioned between the first port and the second port. The system also includes a second check valve fluidically couplable with the third port upon the application of the positive pressure at the first port. The second check valve is positioned external to the valve assembly.