Inlet pipe restricters 2-pipe steam

uptonst

Hi, in refurbishing a 1920s 2-pipe system in a fairly large house (nearly 30 radiators) we're finding some radiators have small "orifice" washers placed just after the inlet valve - basically a metal disc with a small hole drilled in the middle. They're on some radiators but not others, and the hole size varies as well, perhaps from 1/8 to 3/16 or so. My understanding was that this was to restrict steam to some radiators as part of balancing the system, is that right? And how important is it to replace these - can't we get the same effect by partially closing the inlet valve?

If we do need them, where can we get them? Most of the ones we're taking out are rusty and bent. The inlet pipes are almost all 3/4".

We're replacing all the inlet valves and steam traps so would be easier to put these in now than later if we do need them.

thanks! James

Dave in QCA

Orifice system will save your lots of $$$

Here is a link to an artical by Henry Gifford on using orifices on 2 pipe steam systems.  https://869789182725854870-a-energysavingscience-com-s-sites.googlegroups.com/a/energysavingscience.com/www/articles/henrysarticles/BSEOrifices.pdf?attachauth=ANoY7cp3jhKEE1vPo-IJTmNjmWyjbHSkXy-kHdXLWYKJumVBfQNOKtcSqQ6xBpk1tsitud1fJw7jqaoBeJudMmHVfsAykpG4BGIaSZh37SkKbzxsSDEQxg8fpYy80--F1xbbyrC4x85hAXqnkG5v7eYIEmXezfm8nknwcGcRq9Y3txn42Mo02uOfMXuCuEcGv6vO3HvNdHJpkOOvT13vqectXMB6cjxlAo9xAyuFFGGqRX1qXFWIkuw%3D&attredirects=0  It will be very helpful to you.  So read it very thoroughly before you proceed with more work on your system.

Rod

Inlet Orifices

Hi- Those "plates" are inlet orifices and control the amount of steam entering the radiator. As you have noticed the orifices are different sizes to match the size of radiator.

Orifice plates are available from Tunstall http://www.tunstall-inc.com/inletorifice.html

and attached is an article by Henry Gifford on orifices and sizing orifices.

- Rod

uptonst

thanks - but why not use the valve for this function?

Many thanks, this is very useful. Do I understand from this that I'm wasting time/money replacing the old steam traps, or is it useful to have both orifice and trap?

But again, I still don't quite see how the orifice is performing a different function from the valve. Clearly for a TRV it would be different, since the TRV will open and close fully according to temp. But with a regular valve (which is what we're using) would we not get the same result as with the orifice by just cracking the valve open by different amounts according to radiator size? Given the thread size on the valve, it should be possible to calculate whether say 1/4 or 1/2 turn on the valve corresponds to a particular hole size in the orifice. Using the valve like this also gives more flexibility and eliminates danger of clogging, no?

Thanks again, James

Charlie from wmass

People can mess with valves

and they will mess with them too. Also how do you measure the the amount a valve is open? The valve opening will vary depending on how warm the stem is. Expansion of brass will drive you nuts trying to balance the system and then someone will open or close them and throw the whole thing out of whack again. Remember the dead man who installed those orifice plates was paid extra to put them there. Few people paid extra for things they did not need with steam systems.

Jamie Hall

Two things...

first place, Charles is right.  It's one of Murphy's Laws.  I folks are left to themselves, and there is something to fiddle with, they will fiddle.  The results may -- or may not -- be just fine.



Second, some two pipe steam systems are vapour systems, and some vapour systems do not have traps on the radiator outlets.  The dead men, instead, counted on two things to make them work: orifices on the radiator inlets to ensure that no more steam than could be condensed could possibly enter the radiator, and very low pressure to make sure the orifices work.  Before you take them all out and forget which radiator which one came from, at least do yourself the favour of noting what size orifice was in which radiator, so that if you find out that your system is one of those vapour systems which absolutely have to have them to work you can replace them.



This has nothing to do with "balancing the system".  It is simply essential, to make it work at all.

uptonst

OK, makes sense

sounds like I better get hold of some of these orifices! thanks again, James

uptonst

it's a vapour system!

Hi, I went ahead and installed the orifices using the drill sizes listed in the article, fired it up and it seemed to be working. But...I realize now from Dan H's book that mine is a vapour system, with much lower pressure than the 2psi in the article. Does that mean I've drilled all the holes too small? If so is there a similar table for vapour systems? (I saw the 1931 article on this too, it's based on 2-3psi also, has actually even smaller drill sizes per EDR). Thanks! James

Rod

Inlet Orifices

  Lower the pressure and see how that works. Orifices can easily be drilled out if you really feel that would be an improvement. Please let us know what you find out as a lot of people are interested in orifices for steam.

- Rod

Dave in QCA

tables would be helpful

I wonder if anyone, especially the pros might have a table that would provide orifice sizes for lower pressures, such as 1 psi or 8 oz. 

I know that Dunham was offering regulating plates for the vapor systems.  But, the materials that I have been able to find to not reference any size or rating information.

Jamie Hall

It would be nice...

if there were such a table, or tables.  But I have a nasty suspicion that the dead men who worked on these systems may have done it largely by "feel".  The correct orifice size for a given radiator on a given system at a given pressure... urgh.  Lots of variables there, but the sort of thing which one would get a feel for without being able to quantify it.



Fortunately, not hard to play with -- start small, and if the radiator doesn't heat across ream it out a little!

The Steam Whisperer (Formerly Boilerpro)

As you may have guessed.....

I have a table from a 1931 article....however, I forgot where I found it.  I do have a hard copy.  Tunstall also has sizing tables, though, so give them a call.