Suction line diameter of saturated liquids
Suction line diameter of saturated liquids
(OP)
Hello!
I have one question which some of you perhaps can answer: We often design suction line of saturated liquids like ammonia in a way that the velocity in this suction pipe is about 0,8 m/s. Additionally we consider NPSH issues. We never had problems.
My problem is that I do not know why it should not be possible to design the suction line with a diameter of 1,8 m/s. Are there any other parameters I should consider besides NPSH?
In my opinion the valve in the suction line is creating a large part of the pressure loss. Until now we nearly always used globe valves which cause a much bigger pressure loss than for example butterfly valves.
So, what do you think? What is to be taken into account besides NPSH?
Any hint or links appreciated
Kind regards virk
I have one question which some of you perhaps can answer: We often design suction line of saturated liquids like ammonia in a way that the velocity in this suction pipe is about 0,8 m/s. Additionally we consider NPSH issues. We never had problems.
My problem is that I do not know why it should not be possible to design the suction line with a diameter of 1,8 m/s. Are there any other parameters I should consider besides NPSH?
In my opinion the valve in the suction line is creating a large part of the pressure loss. Until now we nearly always used globe valves which cause a much bigger pressure loss than for example butterfly valves.
So, what do you think? What is to be taken into account besides NPSH?
Any hint or links appreciated
Kind regards virk





RE: Suction line diameter of saturated liquids
Double negative intended as reversal, or as amplified negative?
RE: Suction line diameter of saturated liquids
Probably it is a bit confusing. What I wanted to ask:
Is it possible to design the suction line diameter for a suction line speed of approx. 1,8 m/s. What parameters I have to consider?
Kind regards virk
RE: Suction line diameter of saturated liquids
The pressure in bubbles is higher than ambient pressure due to surface tension. It takes more vapor pressure to nucleate a bubble than to grow one after it has formed. Low flow velocity will minimize turbulence that can nucleate bubbles.
RE: Suction line diameter of saturated liquids
I also think the lower the suction velocity the better. But is gets more expensive. Does anyone have any experience in designing a suction line diameter with more than 1m/s for saturated liquids (here ammonia)? Who can give some practical hints?
Kind regards virk
RE: Suction line diameter of saturated liquids