Vertical pipe run and pipe support 1

[BPLBPL]

Hello everyone,
* In a solar hot water closed loop project, I intend to run the vertical raisers (carrying the hot and cold heat transfer fluid)inside a chimney chase 3ft x 3ft. The chase runs vertically from the boiler room to the roof and is about 80 ft long. The problem is how to support the two 2" Copper 'L-type' pipes since there is no access to the chase from anywhere in the building. Will it be alright to have the pipes supported only at the bottom and top? I'm concerned about thermal expansion, buckling etc

* Another flow rate related question: The design flow rate in this closed system is 30 gal / min. I want to know if I can get away with a 1.5" diameter pipe at this flow rate. At these conditions, my flow velocity exceeds 5 ft/s. The industry practice is to keep the flow velocity below 4 ft/s - to avoid noise and pipe erosion I think. If the (2 ft/s < gpm < 4 ft/s) approach is wrong, on what other basis can the pipe diameter be selected for a given flow rate? Note: Flow rate (Q) = Velocity (V) x Area(A)

Look forward to your thoughts, thank you very much.

 

[SNORGY]

I think you can run 5 ft/s in any water system without issues. Even the API 14E rho-v^2 guideline is just that: a guideline; it is largely arbitrary, or so would the copy of the unofficial literature I have regarding its origin suggest.

Otherwise, I am inclined, if possible, to *guide* the risers at the bottom and hang them from the top. Thermal expansion will be downwards without buckling or thusts, much as they would be in a boiler or for that matter a tall contactor with a riser or downcomer hung from the top.

Until someone proved me wrong, that would be my "going-in" position.

Regards,

SNORGY.

 

[BPLBPL]

Thank you SNORGY.

Any other thoughts techies?

 

[btrueblood]

I'm with Snorgy on this one, provided you check the stress on your copper pipe due to the hanging load...

 

[ports394]

Top and bottom should be fine. Be sure that at the top, your bracket/fastener goes across the 3x3 ft chimney, and hang the copper line somewhat through the center of the chimney if you want.

You don't want to secure the pipe to the side of the chimney at the top or bottom and deal with it twisting away from the wall during thermal expansion or hanging.