How to read these 2 charts

stormbytes

For steam main, what is meant by 'T.E.L' ?

I assume the total capacity of the mains should be at least as much as the boiler's output capacity?

For steam velocities, can someone please explain how to use the chart?

TiA!

EBEBRATT-Ed

TEL = Total equalivant feet.

You take a steam main say it's fifty feet of 2" pipe. To this you add the fittings. Say you have 5 elbows. 1 2" elbow may have the same resistance as 5' of pipe (you have to find a chart for that I am guessing)

so 5 elbows @ 5' each =25'

Add 25 to the 50 feet of pipe and you have 75' TEL

So any fittings resistance, elbows, tees (run and branch resistances are different) couplings and unions (they have little resistance)

are expressed in "feet of pipe "

stormbytes

@EBEBRATT-Ed

Thank you that's very helpful.

So I understand 'equivalent length'. The chart is giving pressure drop per 100 INCHES TEL, then the same per 200 INCHES. How do I use this information to determine total

Also, any thoughts on the second chart?

Tia!

DanHolohan

Let's say you're looking to move 1,000 sq. ft EDR though a 3" pipe at 2 psi. Multiply 1,000 by the factor given (.0320). The steam will move at 32 feet per second. That's 21.8 miles per hour.

If you can work with a higher velocity, drop down a pipe size and see what you get. The Dead Men often designed to speeds as fast as 60 mph. It all depends on where the pipe is. You have to be careful with velocities when you're rising out of the boiler. Go too fast and the water goes with you.

Tim_D

The chart should be per 100 feet not 100 inches. One pipe steam systems were typically designed for 1 ounce of pressure drop per 100 feet. The 100 feet is from the boiler to the furthest radiator.

stormbytes

@DanHolohan

Thanks Dan, that clears up a lot!

I'm working on a 100 year old, 2 fam in NYC with a total EDR somewhere between 250 - 400.

What's a good speed to aim for when designing the steam pipes?

DanHolohan

@stormbytes, I've got six pages on that in The Lost Art of Steam Heating, if you have a copy of that book. Velocity is more of a concern with the risers leading to the boiler's header. The classic design from the Dead Men was not to exceed 15 feet per second if you want to keep the water from leaving the boiler with the steam. Fifteen fps is not practical with modern steam boilers, which is what makes the boiler's near-boiler-piping specs so important. I would keep it as low as possible by using multiple risers to the header. The more the better.

For the mains, risers, returns, etc, I would use the charts that show the maximum radiation allowed for each pipe. For instance, don't try to feed more than XXX EDR if your steam main is this size, and so on. Those are also in "Lost Art." There's a chart for every pipe you'll find in any system.