Spill Back System (Recirculate line)
Spill Back System (Recirculate line)
(OP)
Kindly refer to the image uploaded.
May I know, what is the percentage range of the capacity that can be spilled back to the suction of the pump through the recirculate line (restrict orifice located at the recirculate line)?
Can i maximize the capacity of spill back by installing a flow control valve at B (discharge line)?
Thank you for anyone who are willing to help me.
May I know, what is the percentage range of the capacity that can be spilled back to the suction of the pump through the recirculate line (restrict orifice located at the recirculate line)?
Can i maximize the capacity of spill back by installing a flow control valve at B (discharge line)?
Thank you for anyone who are willing to help me.





RE: Spill Back System (Recirculate line)
Installing a great restriction at B will change the flow, but not by a lot.
Looks like a student question to me unless you provide some proper numbers.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Spill Back System (Recirculate line)
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Spill Back System (Recirculate line)
I apologize for my not professional question.
For your information, this spill back system has been design to allow some of the liquid spill back to the suction of pump when not enough liquid from suction source. As I am not the one to design this system, I am not sure the reason of insufficient liquid mention and I am not sure if this is a good design. Some one told me the maximum of the capacity to spill back through restrict orifice is 30 percent (the flow is 0.45m3/hr). As these things confusing me, so I would like to gather more information from experience or professional engineer and I asked those question. I thought it is common design, but I think I am wrong.
I use search tool by typing "recircul", but nothing found. I found page by page in pipeline Piping and fluid mechanism forum but I still cannot find it. Maybe my effort is not enough. Maybe it has been done to death as no one ask about recirculate anymore.
Thank you again for spending your time in this unprofessional thread.
RE: Spill Back System (Recirculate line)
What you are saying is if X amount of fluid is supplied from the source, and you divert some of that flow from the pump discharge back to the inlet the total pump output will now be X plus - well I think that's what you are saying.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Spill Back System (Recirculate line)
RE: Spill Back System (Recirculate line)
Is this statement true? As per my understanding, flow can be controlled by restrict orifice. And whenever there is a separate line (from one line to two lines), if the pressure of both lines are low enough, fluid will flow to both lines. Is my understanding correct?
So if a restrict orifice is installed at the circulation line, the maximum capacity can be 100 percent (but depend on the system)?
RE: Spill Back System (Recirculate line)
RE: Spill Back System (Recirculate line)
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Spill Back System (Recirculate line)
Unlike a control valve, the restrict orifice is calculated for a single flow based on the required pressure drop. So, the flow of the RO is somewhat fixed at one rate and can't be modulated.
RE: Spill Back System (Recirculate line)
Yes, I agree I am lazy to do research on engtips as other situation might not same with mine. You have mentioned twice. I thought this is a forum to post the question and seem like engtips does not have the rule of posting the question.
However, thank you for your reminder. Thank you.
I will try to do some research next time before I want to ask something.
Dear lilliput1 and mk3223,
Thank you for sharing your understanding. I have a better understanding now.
RE: Spill Back System (Recirculate line)
Too lazy, well that's your problem not ours. And yes you can post questions and people if they have a mind to will answer with advise for free - because we are big hearted -- but what we won't do is lead you by the hand or do your job for you.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Spill Back System (Recirculate line)
RE: Spill Back System (Recirculate line)
You have a basic simple installation problem, not a complicated hydraulic problem.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Spill Back System (Recirculate line)
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Spill Back System (Recirculate line)
Noted and thank you for your advise.
Dear LittleInch,
Appreciate of your explanation. From you explanation, I know that we can install a control valve at downstream of pump B to reduce the flow, and prevent pump B to go dry (if possible).
In this situation (if the pump not necessary to be function all the time), can I install a pressure gauge or flow indicator at the upstream of the pump instead of using the bypass line (when the pressure or flow is not enough, the pump will stop automatically)?
RE: Spill Back System (Recirculate line)
Pressure indication is essentially the same as a level control and in some cases you can use a sensitive pressure transmitter at the bottom of the tank as a level indicator, but on a pump inlet it is difficult to get the setting right.
Flow indicators are again not easy to set up and in my experience are often quite simple devices which can malfunction and not work properly.
If you're going to add anything, add level switches or transmitters in the tank you're pulling liquid out of.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.