Hi,

this is a followon to my previous questions about columns, etc.

In trying to debug my system (Waters 600E with 225 uL pump heads) I have been plagued by pressure spikes.

I have replaced both pump seals and all check valves. Running the pumps into lengths of tubing gave fairly flat pressure tracings-- very rare spikes, and only at certain flow rates.

I reconnected ot the column (TOSOH TSK-Gel 4000) and the pressure spike gremlins have reappeared. I am concerned because the colmun has a max pressure of about 200psi and I am concrened that high pressures collapsed previous column beds.

They are positive-deflection spikes about to about 120% of the ambient presssures, and they occur at each cycle of the pump heads-- whenever either pump changes direction.

they occur with helium-sparged water and 20% methanol.

Running the pumps at high speed with the reference valve set to divert the flow to waste rather than the column didn't help.

Any suggestiosn greatly appreciated!