Measuring System Pressure on Agilent 1200

Hi guys,

I'm fairly new to LC, and I'm trying to figure out what the system pressure for our Agilent 1200 HPLC system is. I'm running phosphate buffers through the system to do SEC, and when I put a union in place of a column, I get around 25 bars at a flow rate of 0.5 mL/min. If I use a column, I get around 28 bars at the same flow rate. The column has a max pressure limit of 200 bars according to the manufacturer's spec.

I understand that I shouldn't operate at the pressure limit of the column, but for my knowledge, given the above scenario, am I right to assume that as long as the total pressure doesn't exceed 25 + 200 (system pressure + column upper pressure tolerance), the column is operating within its pressure limit?

Thanks a lot in advance,

jyanglaststar

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kbusch over 4 years ago +2 verified

Basically, everything prior to the column is not contributing to the column maximum pressure. However, the pressure when including the column, as well as any pressure generated after the column will all…

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0 kbusch over 4 years ago

Basically, everything prior to the column is not contributing to the column maximum pressure. However, the pressure when including the column, as well as any pressure generated after the column will all be included in the maximum pressure of the column.
Essentially, Maximum column pressure limit cannot be exceeded by pressure generated by the column + pressure generated after the column (from capillaries, flow cells, etc.).
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0 jyanglaststar over 4 years ago in reply to kbusch

Thanks for your explanation, kbusch. Is there a way to measure/monitor the pressure generated after the column? I suppose the 25 bar when a union is in place is the total pressure prior and after the column?
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0 jyanglaststar over 4 years ago in reply to kbusch

Thanks for your explanation, kbusch. Is there a way to measure/monitor the pressure generated after the column? I suppose the 25 bar when a union is in place is the total pressure prior and after the column?
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0 kbusch over 4 years ago in reply to jyanglaststar

You could disconnect the capillary that goes into the union. Then run the liquid into a waste beaker. Monitor the pressure and then subtract from 25. Normally, there is only little pressure generated from the last capillary and flow cell. Mostly, the pressure reading from the sensor should be kept below your column reading, that way there is more control in preventing column overpressures.
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