From page 14 "The Lost Art of Steam Heating Pressuretrol"

jhobbselectric

In your example for 16 oz are you referring to water weight or ounces of steam? At one point I read "16 oz of pressure at boiler" yet in final you write, "12 ounces at radiator. My question is in ref to PSIG. Are you saying you start out with 16PSIG? Can someone explain.

STEAM DOCTOR

Ounces of pressure per square inch. 

jhobbselectric

steam or water?

jhobbselectric

Got it in book if the conversion factor of oz to lb would have been noted I would have saw it. So the author is saying that he started out with app 1.04lb of steam. ( 16x.06249=.99 psi of steam.) In his example of 8oz being equivalent to 1/2psi... Thank you

Jamie Hall

pressure is pressure. It doesn't matter what medium you are considering. Possibly the confusion is that sometimes pressure is measured as being so and so many inches of water or mercury. What is meant is that the pressure in question -- for instance in a steam header -- is sufficient to support a column of water (or mercury) so many inches high with the other upper end being at atmospheric pressure (usually -- in which case it should be called gauge pressure, but that's usually understood, which can cause confusion).

In the immediate above confusion the omission -- also customary -- was in leaving "per square inch" out of the measurement of pressure in ounces. It should have been to be quite pedantic, "ounces per square inch gauge pressure or pounds per square inch gauge pressure", but that is usually understood.

jhobbselectric

pedantic-an insulting word used to describe someone who annoys others by correcting small errors, caring too much about minor details..... Not so sure by asking a questing I would be annoying.. Probably wont be back not to worry Mr>Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England

Sylvain

@jhobbselectric
If something is not expressed with enough rigor, one is perfectly entitled to ask questions to exclude any ambiguity.
There are no bad questions, only bad answers.

I have to ask for more precision regularly when my wife asks for something. It avoids a lot of misunderstanding ;-)

I think what Jamie hall was expressing is that some people would have found the book pedantic. It isn't directed against you.

Jamie Hall

My goodness. Well, since I was using the term "pedantic" to describe myself (and it is accurate enough, applied to me), not @jhobbselectric , I'm sorry that I caused offence simply by using the word. It's getting kind of hard to determine just what is going to offend someone these days.

Sylvain

To answer to the Op question:
On this site and in the book
- ounces are ounces per square inches above athmospheric pressure [whatever it is];
- psi are pound per square inches above athmospheric pressure;
- inches of mercury on this site are used for vacuum, so pressure under athmospheric pressure (with 1 inHg = 0.489 771 psi [at 60*F]);
- inches of water are used to express a difference of pressure between two points in a water circuit.
1 inH2O ≈ 0.03612729 psi or 1psi=27.6799...inH²O (at 4*C).

Now, I am a metric guy; I would prefer to use just one unit (bar or pascal).

PC7060

Sylvain said:

Now, I am a metric guy; I would prefer to use just one unit (bar or pascal).

Agree, so much simpler. 

SteamingatMohawk

I have the revised LAOSH, page 26:




You wrote, "So the author is saying that he started out with app 1.04lb of steam. ( 16x.06249=.99 psi of steam.) In his example of 8oz being equivalent to 1/2psi..."

I am not sure how your 1.04lb of steam enters the conversation (perhaps my copy has different text from yours).

But your multiplication confuses me. The 16 being the weight in ounces for 1 lb of just about anything, except gold. The decimal of .06249 is somewhat odd in that 1 divided by 16 = .0625, not what you wrote.

So, 16 x .0625 = 1.000.

What don't I understand?