Condensate Return Line

Two reasons come to mind.

1. Condensate needs to be returned with as little pressure applied to it as possible from the point of view of the steam service user's requipment. Increasing the pressure downstream of the trap will cause a significant fall-off in performance of the heating side of the user's equipment. "Don't lift condensate without using a pump".
2. The condensate really does not need to boil to steam as the pressure drops quickly with distance along the condensate return line.

that table for sizing condensate return line to the trap spirax sarco make this steps:

• firstly determine condensate rate at start up say it is 243.15 kg/h.
• second step enter table with Δp/m ≤ 200pa/m, then choose the first pipe size which can stand up capacity = 243.15kg/h it will be 15mm.
• third step check on Δp/m if it was less then 200pa/m so it is acceptable and if not use anther pipe size to be more then 15 mm and can stand up capacity = 243.15 kg/h.

the question is why it limited by 200pa/m and not more hem it.

....for the practical considerations above, perhaps?

do you think use this table is wrong for sizing condensate drain line to trap ?

that I should use this equation H_lose= 0.8×f×L×Q²⁄g×d^5.is better then use the last table.

It is known that for every fluid at certain temp., there is a recommended velocity which minimize the pressure drop. And the size of pipe and fluid velocity have a great influence in determining the pressure drop.

And the table was designed for a limited and recommended pressure drops, to be fellowed. So for other values of pressure drops, behind what is recommended, there shall be another values for flowrates.

200 pa/m is a recommended pressure drop for condensate return line and this number was advised from spirax sarco !

the question is why this number why not say as an example 300 pa/m

also the table can cover all condensate rate .