Chilled water pipes?

Question

During designs for chilled water systems for normal pressures (150 PSI) when do we use black steel pipes and when do we use ABS pipes what I know is that ABS is more preferable to use for burried pipe networks, but I got to know that it may be used for the whole system. Also when we use ABS how do we get the friction rate to calculate the pressure drop in the system

Answer 1

Friction factor for ABS use the same as PVC pipe (0.000005 in/in)

ABS plastic pipe is more susceptable to damage that is why most specifications will call for steel pipe indoors. ABS pipe will need better supporting, (more pipe supports than black steel pipe would). Not sure what the pressure rating for ABS plastic pipe is compared to steel. Just make sure the shut off pressure (dead head pressure) on the supply pump is not close to the ABS rating.

But if you got a large plant, I would stick with steel pipe. If this is for an office building where the pipes are located in the ceiling plenum, then ABS would be ok.

To calcluate the pressure loss, use the Darcy-Weisbach equation, there is a online calc for this but not sure of the website.

Also, there are charts for fluid flow in pipe that give a pressure loss per 100 ft for various flows and pipe sizes. This is for straight pipe, add 15% for fitting and valve loss and that would be close. Try to use the Darcy Weisbach equation. There are also charts that give loss for fitting and valves.

Answer 2

You have to know two things to calculate the "frictional head loss" (essentially pressure drop) of fluid flow through a pipe:

1.
The Reynolds number of the fluid flow, calculated by
Re = rho*v*D / mu
where rho is the density of the fluid, v is the average velocity of the fluid, D is the pipe diameter, and mu is the viscosity.

and

2.
The scale of the roughness of the pipe's interior, as a fraction of the pipe diameter.

Then you use a Moody chart, like this one

http://www.cbu.edu/~bbbeard/313/MOODY6.gif

to find the friction factor, f. Once you have f, you use this equation to find head loss:

Head Loss = f*L*v^2 / D
where f is the friction factor, L is the pipe length, v is the average fluid velocity, and D is the pipe diameter.

However, that is only the head loss due to straight pipe sections. Joints or branchings in the pipes will each contribute their own small amount of head loss. You'll have to look up the exact amount for each pipe joint separately if you want a truly accurate answer.

Answer 3

not the place looking it, however the tubes if it might desire to circulate remoted by making use of the radiation that one types between 2 borders of the pipe and the outdoors atmosphere that diverse temperatures have