Decoupler Pipe
Decoupler Pipe
(OP)
Hello,
I need help in calculating the Size of Decoupler pipe in my project. I heard the pipe size should be the size of header of the chiller which is 8" for my project. And also do i require to install any kind of control valve, if yes, what type of valve it should be, and from which point it gets input for mudulation. Also do i need to install a check valve.
My project consists of 8 chillers each 400 tons with dedicated pump (60 ft,1000 gpm Vertical Inline) for each chiller and one set of secondary pumps serving to 4 sets of secondary pumps to 4 buildings.
And also if there are any notes or study material for decoupler piping , please share.
I need help in calculating the Size of Decoupler pipe in my project. I heard the pipe size should be the size of header of the chiller which is 8" for my project. And also do i require to install any kind of control valve, if yes, what type of valve it should be, and from which point it gets input for mudulation. Also do i need to install a check valve.
My project consists of 8 chillers each 400 tons with dedicated pump (60 ft,1000 gpm Vertical Inline) for each chiller and one set of secondary pumps serving to 4 sets of secondary pumps to 4 buildings.
And also if there are any notes or study material for decoupler piping , please share.





RE: Decoupler Pipe
RE: Decoupler Pipe
RE: Decoupler Pipe
Each pumps needs check-valve. No need for valves (although I'm not sure what you try to do... I assume normal primary/secondary loop?)
RE: Decoupler Pipe
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Best to you,
Goober Dave
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RE: Decoupler Pipe
RE: Decoupler Pipe
Yes its a normal Primary-Secondary setup. As per the theory i have referred authors are suggesting a Modulating valve in Decoupler pipe for a Variable Primary systems only ( it is understood that to keep minimal flow through chiller in low load conditions a modulating valve is installed ), whereas in Constant- primary, variable secondary systems, they suggest not to install any valve in the decoupler pipe.
My question
1. In the university project where i am working , other buildings have the same Primary Constant- Variable Secondary systems, yet they installed a modulating valve in a decoupler pipe, is that correct ?
RE: Decoupler Pipe
What you mean by variable primary flow is only having one loop, with a fake primary loop and dp sensor and valve to allow flow through boiler/chiller. For that you cannot use a decoupler. Because decoupling would not make this work.
think exactly about the meaning of decoupling and you will understand. You basically make whatever happens in sec. loop irrelevant for primary loop - you decouple them.
RE: Decoupler Pipe
The whole thing is how do you intent to use the valve? or the flow meter? most rely on the information to stage the chiller/boiler plant, when to bring the next chiller/boiler ON or OFF, combined with Delta T reading.
The idea behind the control valve is to insure that the secondary flow does not exceed the primary flow when running with only one chiller/boiler and avoid mixing of water.
An asymmetric plant design tends to correct that - asymmetric = different size chillers/boilers.
As for the decoupler size, it is never the main pipe size, you should look into partial load figures and size accordingly. In your case of 8" main - 6" decoupler will definitely do the job, 4" will likely do the job.
RE: Decoupler Pipe