Flow correction for back pressure regulated rff flow modulator

A system comprising:

• data processing hardware;
• and
• memory hardware in communication with the data processing hardware and storing instructions that, when executed on the data processing hardware, causes the data processing hardware to perform operations comprising:
• when a reverse fill/flush (RFF) flow modulator is in a calibration flow condition including a primary column flow into the RFF flow modulator from a primary column and a secondary column flow from the RFF flow modulator to a secondary column, directing initial switching flow into the RFF flow modulator in a first direction to an exhaust with pressure regulation and reducing the initial switching flow to a minimum switching flow where a pressure of the RFF flow modulator satisfies a regulation condition;
• determining an adjusted switching flow for the calibration flow condition;
• determining a switching flow profile based on the adjusted switching flow for the calibration flow condition;
• determining an operating switching flow based on the switching flow profile;
• and
• with the RFF flow modulator is in an operating flow condition different from the calibration flow condition, directing the operating switching flow in the first direction to the exhaust.