11 replies to this topic

[zahraniazi]

hi every body

 

there is a polished water tank which has blanketing nitrogen. can it has inlet nozzle in bottom? 

[fallah]

Hi,

 

Inlet nozzle in bottom for incoming water? Or incoming nitrogen?

[zahraniazi]

incoming water ofcourse.

[fallah]

Hi,

 

Would you please explain about your concern regarding location of inlet nozzle.

[zahraniazi]

i read something about we can put inlet nozzle for every kind of tank except which has blanketing connection. now we have demin water tank which has blanketing connection. i need to know that if we have inlet nozzle for incoming water for this kind of tank, and if we dont, why not?

[fallah]

Hi,

 

As per my experienced, for demin water tank equipped with blanketing system the inlet nozzle for incoming water is on the shell near the top and the nozzle for N2 injection is on the roof.

[zahraniazi]

is there any reasons for that?

[fallah]

Reasons for what matter?

[zahraniazi]

for considering inlet nozzle at the top of tank.

[fallah]

Hi,

 

The main reason of considering the inlet nozzle at the top of the tank is to avoid back flow, provided that the inlet line to be extended inside with a dip pipe and also a syphon breaking hole to be considered to avoid back syphoning...

[zahraniazi]

sorry, but we can put a check valve on the inlet line to avoid back flow and after that we dont have spare pipes for carrying water at the top of tank. besides this design desn't need syphone breaker and that dip pipe and... . my colleagues said there is normal for water tank that they have inlet nozzle at the top of tank, but in the petroleum tank, the inlet nozzle is in the bottom of tank. i cant underestand what is difference between these two?

[fallah]

Hi,

 

If you look at the matter in HAZOP review standpoint, you cannot take any credit for a check valve in order to back flow prevention...

 

But nevertheless, there are the tanks (especially in water and fire water applications) in which the inlet lines have been connected to the tank shell neat the bottom...It might relevant designers have already accepted the consequences or the situations have been such that they have expected there wouldn't be any consequences for such situations...