Steam pressure losses through piping

ChrisJ

I found some great information on this and wanted to share it.

This calculator will tell you what pressure drop you have for whatever amount of steam you're trying to push through the pipe. It also tells you the speed. Apparently the steam in my long main travels at around 15mph and 10mph in my header

http://www.tlv.com/global/TI/calculator/steam-pressure-loss-through-piping.html

A good pressure chart for converting inches to psi.
http://www.engineeringtoolbox.com/pressure-converter-d_825.html

And this page explains how to calculate boiler horsepower and pounds per hour.
http://www.engineeringtoolbox.com/boiler-capacity-d_1115.html

ChrisJ

I just spent quite a bit of time coming up with this. What's interesting is it kind of explains why I need the vents I do in certain places. For example the main bedroom vs the back bedroom. Same size rooms, almost same size radiators but completely different vents.

If I did my math right, running at 0.75" w.c. I should end up with 0.50" w.c. at my furthest radiator.

ChrisJ

I used the EDR of each radiator.
Amount of flow per main is done by total EDR connected and then subtracted from the main as I went down the line.

I couldn't see any other real way to do it.

The mains are both 2".
The only long horizontal run outs are :
Top of stairs : 5 foot horizontal
Downstairs bathroom : 10 foot horizontal
Main bathroom : 10 foot horizontal
Thermostat : 10 foot horizontal
Small bedroom : 10 foot horizontal.


The Thermostat radiator I added 1 foot to my calculation for the vertical connection through the floor.

ChrisJ

Hatterasguy said:

That was a LOT of work.............

Each section of main required its own flow rate for the calculation of piping loss through that section.

I had originally done a calculation on mine using 50% of the flow rate through each main.............all the way to the end of the main. Clearly in error.

But, my results show that my piping loss is approximately the same as my pressure, .1 psi. Again, this is incorrect as the piping loss is not as great due to the reduced velocity each time the steam passes a riser.

I'm unable to do the same calculations as you have done as I don't have any of the riser lengths.

Wow,
Why so high? What size and how long are your mains and how much are you pushing through them?

ChrisJ

Hatterasguy said:

I ran it for the 60' main with 1/2 the boiler capacity............131KBTU. The main is 2.5".

But, I did not reduce it for each riser along the way. That's why it's so high.

I didn't include 45 or 90 ells in mine and I am thinking about redoing it.

Or maybe just increasing the numbers by 5% or something.

But yes, it was a lot of work.

Mark N

Chris, have you considered putting your low pressure gauge at the end of your long main and getting a pressure reading. If that reading could be obtained it would make it easy to determine the pressure drop from the boiler to the end of main.

Mark N

Also a few years back I remember someone placing a pig tail and a gauge on a rad and getting a pressure reading there.

ChrisJ

I'm thinking about hooking my Dwyer manometer up to a few radiators and seeing what I get.

I'd rather not unhooked the magnehelic, though I've thought about that as well.