GPC detector problems

[ilyphotocip]

Hi,
We have an GPC Waters Breeze System(Isocratic HPLC pump 1515; 717 plus Autosampler, 2414 Refractive Index detector and 3 columns Styragel HR1xHR 0.5xHR0.5; Flow rate = 1 ml/min).In this moment we changed 2 valves on the detector:Solenoid valve and Relief valve, because it flows in the same time on the purje mode and on the analysis.Four mounths after, this the GPC system it works, but after it begining again .What's happening? In this moment we change the flow rate= 0,5 ml/min, and it works normal(p=400 psi) .If I try to grow up the flow rate to 1 ml/ min,it flow again. Please help me.
Thank you,
Ileana

[uzman]

Check the detector outlet tubing ( waste tubing ) if it is clogged or not.
Also the inside diameter of this tubing is important for RI detectors.

Mostly , 0.5mm or greater ID tubing must be used , in order not to apply backpressure to the cell and solenoid valves , and also the tubing must not be too long.