| 摘要 |
A system for regulating a pressure of a piston on a bed in a flow through column system, where the flow through column system includes a piston pressure chamber in communication with the piston and an inlet line and an outlet line in communication with the bed. A pump has an inlet in communication with a supply of hydraulic fluid. A forward pressure reference communicates with the inlet line. A forward pressure regulator has a reference inlet in communication with the forward pressure reference and an inlet in communication with the pump. A switching valve communicates with the piston pressure chamber, and also has a inlet in communication with the outlet of the forward pressure regulator. A back pressure reference communicates with the outlet line. A back pressure regulator has an inlet in communication with the outlet of the switching valve, a reference inlet in communication with the back pressure reference and an outlet in communication with the supply of hydraulic fluid. The switching valve may be manipulated so that a pressure in the piston pressure chamber is controlled by either the forward pressure regulator or the back pressure regulator.
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