A fluid sampling device (100, 200) for acquiring a representative fluid sample from a fluid source, the fluid sampling device comprising: a sample vessel coupled to a sample inlet port (104, 204) and a sample outlet port (118, 208); a first conduit configured to couple an outlet (102, 202) of the fluid source to the sample inlet port; a second conduit configured to couple the sample outlet port to an inlet of the fluid source (120, 220); an expansion chamber comprising an inlet and an outlet coupled to the first and second conduits by a valve assembly; and a pressure relief valve configured to couple the outlet of the expansion chamber to the inlet of the fluid source, wherein fluid from the fluid source is to flow in a closed loop between the sample vessel and the fluid source when the valve assembly is in a first position, thereby flushing the sample vessel, and wherein the fluid is to flow in a closed loop between the sample vessel and the expansion chamber when the valve assembly is in a second position, thereby expanding a portion of the fluid in the sample vessel [claim 14], wherein the first conduit is further coupled to an inert gas source such that: inert gas from the inert gas source can push fluid within the first and second conduits toward the inlet of the fluid source when the valve assembly is in the first position, thereby purging the first and second conduits, and inert gas from the inert gas source can push fluid within the expansion chamber towards the inlet of the fluid source when the valve assembly is in the second position and the pressure relief valve is opened, thereby purging the expansion chamber. a sample vessel coupled to a sample inlet port (104, 204) and a sample outlet port (118, 208); a first conduit configured to couple an outlet (102, 202) of the fluid source to the sample inlet port; a second conduit configured to couple the sample outlet port to an inlet of the fluid source (120, 220); an expansion chamber comprising an inlet and an outlet coupled to the first and second conduits by a valve assembly; and a pressure relief valve configured to couple the outlet of the expansion chamber to the inlet of the fluid source, wherein fluid from the fluid source is to flow in a closed loop between the sample vessel and the fluid source when the valve assembly is in a first position, thereby flushing the sample vessel, and wherein the fluid is to flow in a closed loop between the sample vessel and the expansion chamber when the valve assembly is in a second position, thereby expanding a portion of the fluid in the sample vessel [claim 14], wherein the first conduit is further coupled to an inert gas source such that: inert gas from the inert gas source can push fluid within the first and second conduits toward the inlet of the fluid source when the valve assembly is in the first position, thereby purging the first and second conduits, and inert gas from the inert gas source can push fluid within the expansion chamber towards the inlet of the fluid source when the valve assembly is in the second position and the pressure relief valve is opened, thereby purging the expansion chamber. inert gas from the inert gas source can push fluid within the first and second conduits toward the inlet of the fluid source when the valve assembly is in the first position, thereby purging the first and second conduits, and inert gas from the inert gas source can push fluid within the expansion chamber towards the inlet of the fluid source when the valve assembly is in the second position and the pressure relief valve is opened, thereby purging the expansion chamber.