I am assuming that by system pressure you mean the back pressure to the suppressor device. The recommended backpressure to the eluent channel of Dionex membrane suppressors is 40 psi and is independent of flow rate.
If the suppressor leaks under these conditions here are some things to check for
1) Check the line out of the regen out port and ensure that this line does not contribute to backpressure. Dionex recommends the use of 1/8" tubing for this line.
2) In electrolytic suppressor devices the eluent and regenerant flow should be established when the power supply is turned on. If the suppressor current is applied without establishing the flow, this can irreversibly damage the suppressor device and in extreme cases can lead to leakage
Solution: Always ensure that the suppressor current is on when the flow is on.
3) High internal backpressure in the suppressor can cause leakage. This scenerio can be caused by the sample matrix conditions. For example presence of high levels of iron will cause precipitation reactions within the suppressor causing high backpressure within the eluent and regen channels. This high backpressure can lead to device leakage. Refer to the suppressor manual for cleanup steps.
Note the suppressor voltage can be monitored using the CD detector. When precipitation occurs the suppressor voltage increases and this voltage could be used as an indicator to trigger a cleanup step for the suppressor.
4) If operating in the external water mode, ensure that the suppressor regenerant flow is within the recommended value. Operation outside the recommended flow rate range may lead to leakage.
I hope this helps.
