Dear all,
Will you please explain the application of liquid trap, in a condensate drain drum of gas lines.In that exit( gas exit) of the drum has a balancing line connected to this liquid trap located at drain line of drum. whats application of this balancing line.
Please clear the doubts.
Regards,
Stu.

As liquid (saturated) from vessel flow into the liquid drain trap, pressure drop along the line may results small amount of vapor form. The vapor may stay and accumulate in the liquid trap. Subject to line arrangement, the vapor may just accumulate in the liquid trap and slowly travel back to vessel via inlet line in the reverse direction to liquid flow. This result inefficient operation.

Thus for some small liquid traps, there is a vent connection on the top of the liquid trap so that vapor generated & accumulated in the trap can vent back to the vessel via a separate vent line. This line is call equalization or balancing line.

Dear sir,
Thanks for your reply.I had another querry regarding this.
The drain line from the liquid trap is connected to open drain( normally atmospheric pressure) where the pressure is lower than the drum operating pressure, in this situation whether the gas in the trap moves to low pressure area(open drain line) or to the higher pressure drum side.
Please explain & correct me where my understanding is wrong.
Thanks.
Regards,
Stu.

Stu,

Please search for liquid trap literature from vendor website and understand how it work. You will find the answer. Click here

Gas will flow back to the drum...