I have a continuous distillation column where the vent of primary HE is equalised with collection tank. The collection line of primary HE is a 2" dip pipe with anti-syphon hole. The tank vent is equalised with secondary HE. The collection line from secondary is a 1" dip pipe without any anti-syphon hole. There is a pressure control valve set @ 700 mmWC on secondary HE vent line to maintain back pressure in entire system.
I am observing vacuum in collection tank and secondary HE.
Is there any possibility that secondary HE would develop vacuum and would hold liquid column upto barometric leg due to vacuum and no anti-syphon hole in collection line? Or dip pipe would remain empty as both secondary HE and tank are equalised and both are at same vacuum condition.