why we don't see saline coming from dialysate inlet & outlet during priming low flux dialyser & we can see this during priming high flux dialyser.if we see in low flux dialyser what can be the reasons. thanks

FLUX refers to how easy solution passes throught the membrane of the dialyzer. A HIGH flux dialyzer allow solution through very easy and doesn't require a lot of pressure. A LOW/NORMAL flux dialyzer does not let solution through as easily and requires more pressure to push it through.
Hope this helps