Pressure at 0 flow rate

[MikeT]

Hey guys,
A quick question. I am working with a UHPLC. When I start the program, at 0 ml/min it shows me a backpressure of 170-190 psi. When I disconnect the column and/or the nut for the inlet filter of the pump, nothing changes. I don't understand... is this normal?
Thanks so much for the help.

Mike

[H2Oh]

I don't have much experience with UHPLC, but with the ICs and HPLCs here, this happens when the pressure transducer is in need of calibration (our old Dionex ones have a single point, 0 pressure, calibration). Does the pressure respond normally when tested with a backpressure loop of known pressure/flow rate?