What role does the gas-phase tube play in the liquid ammonia loading arm?

 Because liquid ammonia is a volatile material,In the process of loading and unloading, it is necessary to set up a gas pipe balance tube,Before filling liquid of the liquid ammonia loading arm, there are gas components in the container,To ensure smooth filling,Need to balance the tube to drive the gas phase assembly away,Otherwise, it cannot be filled after being filled to a certain degree (unless it is pressurized); during the discharge process, as the material in the container decreases, the pressure will inevitably decrease. At this time, the pressure can be filled into the container through the balance tube to ensure the discharge Smooth and thorough.