Napier steam orifice chart for ounces

tim smith

I have been searching on heatinghelp and on line and can't find it. Any one have one I could get. Also attached is an orifice graph but I am wondering about its accuracy at 8 oz? I checked it against an online calculator and not quite sure which if any are accurate.
appreciate any help,
Thanks
Tim

dko

how is this one

tim smith

thanks a lot, I appreciate it.

JUGHNE

The Napier one is what I used, actually those are my notes written on it.

I got it from "Fizz" on 6-9-14....seems like yesterday.

The last column for 2 PSI (32 ounces) agree with the Henry Gifford chart.

Also includes some Jamie Hall advice for 2 pipe system operation.

jumper

An interesting subject. I remember Mechanical Engineering professors discussing measured results versus gas theory calculations.

JUGHNE

The notes marked up in that chart were from a house I redid in 2014.

Most of the supply valves were shot, broken or stripped out.
I changed to a standard RWV brand valve.

Most traps were empty. Some broken elements removed. All traps are empty.

I just took my best guess and used the 18 ounce size @ 80% of EDR.

You do not want to go too big, these can always be enlarged.

If I were you there, I would try to get all the valves adjusted to about 80% of rad fill.

Then adjust the pressure down at the boiler with a vaporstat to see what the highest pressure would be needed to heat the building......getting pretty warm outside for that test.

If the piping looks to be original and not chopped up, my best guess is that it would run on less than 1 PSI. Others with more experience in this matter here could chip in.

The air elimination device which used to vent into the chimney was long gone.
No air vents at all, other than a couple misguided attempts to install rad vents on this 2 pipe system.

All pipe slope was checked and corrected as needed.

I added 2 Gorton 2 on each end of the 2 steam mains at boiler.

Also Gorton 2's on the dry returns, as it turned out these never saw any steam.
The dry return was actually cool in the basement.

System worked great and quiet.

Homeowner insulated pipes.

Mad Dog_2

Keep us posted Tim.  Mad Dog 🐕 

tim smith

I will Matt, it will be over the summer mostly.
Thanks again all,
Tim

Mad Dog_2

Cool. I love these projects.  Mad Dog 🐕 

jumper

Does pressure matter? Especially with empty traps. Undersize inlet orifices and see if any room is under heated.When windows are replaced with double pane required radiation is reduced substantially.

>>Then adjust the pressure down at the boiler with a vaporstat to see what the highest pressure would be needed to heat the building......<<

JUGHNE

If you have a 59 EDR rad and want to get only 80% of that 59 to give you 47 EDR delivered, you would use a 1/4" orifice at 18 ounces. This would deliver 44 to 48 EDR.

All of this is based on the orifice chart posted above.

If that pressure went up to 32 ounces (2 PSI) then it would pass in the range of 77 to 86 EDR.....overheating with windows open and steam going into the dry return.....assuming no traps.

Or if you could run the system at 12 ounces then the 1/4" would only pass 29 to 31 EDR.....about 1/2 of the original 59 rating......probably be enough heat the room if the rads were the typical oversized or envelope improvements done to the building.

IMO, you do want to caution towards the smaller orifice, however increasing sizes in an apartment complex could get time consuming.

You could tweak the system by raising the pressure slightly in cold weather for more heat.

I was lucky for this house that had only 10 radiators. There was never a chance to run the boiler, before the work, to get a feel of how low the pressure could be.

No changes to orifices were made and the customer was happy.

Also all the air had to be vented thru each radiator orifice. So I added steam main vents to speed things up for steam delivery, just like one would do for a single pipe system.


Another case was a 1932 school house. A 13,465 sq foot building with 1.4 MBtu output boiler.
It was originally calculated to have 90 to 106 BTUH/ft load.

You could heat the place with the windows partly open...some were.

So room by room, when the building was empty, I would sit and "Shin Fay " each room.
Some rads capped/removed, some windows closed up, remaining windows were replacements and ceilings were dropped. Where was the wind coming from, how many outside walls etc.

From this meditation, or cipher, you might say, I sized orifices for each rad.

Some at 50% and most at 60%. The gym, which had failed hanging heaters, had no orifices and just new traps.

Several winters and no teacher (all women BTW) called with an issue.

The Steam Whisperer

Hey Jugne, have you ever tired installing some non- spring teflon ball check valves on the vent piping? I've got several systems set up like that so they now draw a natural vacuum on boiler shut down... about 5 to 8 inches. This should eliminate the need for big vents on the systems since most of the air is already out of the system from the previous heating cycle and the vacuum checks...assuming the system is tight. This even works well for systems we've upgraded to supply valve orifices.

ethicalpaul

I tried to make some. If they were able to be cracked open under pressure, then they wouldn't hold under vacuum. If they held under vacuum, they were too resistant to opening under pressure. It's hard to find a check valve that works when the pressure typically maxes out at .25 inches of water column

The Steam Whisperer

I"ve used the 3/4 inch Apollo 61-104-A1 mounted vertically so that just of weight of the teflon ball is holding the valve closed. There is no cracking pressure rating on them, but they have worked for me.

JUGHNE

I never tried a check valve for venting.

At that 1930's school I did add EOM venting using Big Mouths.

I did add valves under them in case they stuck open and someone could shut them off.
This job was 50 miles away.

jumper

ethicalpaul said:

I tried to make some. If they were able to be cracked open under pressure, then they wouldn't hold under vacuum. If they held under vacuum, they were too resistant to opening under pressure. It's hard to find a check valve that works when the pressure typically maxes out at .25 inches of water column

Try multiple wimpy check valves in series.

mattmia2

jumper said:

Does pressure matter? Especially with empty traps. Undersize inlet orifices and see if any room is under heated.When windows are replaced with double pane required radiation is reduced substantially.

>>Then adjust the pressure down at the boiler with a vaporstat to see what the highest pressure would be needed to heat the building......<<</p>

The volume of something that passes through an orifice is a function of the pressure and the size of the hole. Steam is also compressible so the higher the pressure the more steam there is in a given volume. Controlling the pressure is critical to the approach of using orifice plates to control the amount of steam that is supplied to radiators and making sure that it is not more than the emitter can condense.

ethicalpaul

jumper said:

ethicalpaul said:

I tried to make some. If they were able to be cracked open under pressure, then they wouldn't hold under vacuum. If they held under vacuum, they were too resistant to opening under pressure. It's hard to find a check valve that works when the pressure typically maxes out at .25 inches of water column

Try multiple wimpy check valves in series.

There is no commercial check valve wimpy enough that I could find although @The Steam Whisperer 's idea of vertically mounting a ball-type one is closest to what I was trying to make.

I even bought one of those Apollo's, maybe I can find it and remove the spring and try it...I can't remember if I did that already

dko

-A1 suffix is without spring

mattmia2

Obviously the bigger the face of the seat the more force on the ball although the ball also gets heavier as it gets bigger. Those tinly flap valves might not work so well since the seat is very small.

ethicalpaul

at my system's typical pressure, nothing works so well, I've tried

mattmia2

Maybe a small blower and a steam trap is the way to go.

mattmia2

or a blower, steam trap, and check valve, the blower produces enough vacuum to open the check valve.

tim smith

Now that I started this I am going to play devils advocate just to be sure. Anyone here overly concerned about using orifice plates with low presssure based on the chart at 80% edr . What are critical points that concern you.

mattmia2

Too big is far more of a concern than too small. If you start getting steam in the returns it will keep other radiators from heating. If you have too little steam just that room is a little cool.

The Steam Whisperer

tim smith said:

Now that I started this I am going to play devils advocate just to be sure. Anyone here overly concerned about using orifice plates with low presssure based on the chart at 80% edr . What are critical points that concern you.

I have consistently found on systems installed after around WWI that when comparing historic heat loss of the building (calculated by fuel usage) to the installed radiation, that a 60% sized orifice is right on the money. Tunstall recommends to design for a higher pressure drop at the orifice (3psi IIRC) if you are using a modulating input boiler ( I run mine on direct outdoor reset of the boiler input) and you can go lower without a modulating system. You tend to get some howling at the higher pressure drop, so I shoot for 1.5 to 2 psi on my modulating systems. Otherwise, I usually use between 0.5 psi to 1 psi, so I can run the system without a condensate pump. The higher pressure drop give you much better "valve authority" so the pressure drop from the system piping has little impact on the steam distribution. This is especially the case when you only fire the boiler to heat 60% of EDR. However, even on formerly vacuum systems with their much smaller piping, I haven't had much problem with even distribution of steam. I have several former vacuum pump systems operating with orifices quite nicely in30 unit buildings.

reggi

Interestingly enough and overly simplified as far as total engineering of the unit but on the Richardson type air expeller for example there is a port exposed to the atmosphere that has a hinged weighted disc ( like a vertical swing valve) on the body of the expeller that opens to let pressure out ( the weight of the disc could determine it's cracking pressure, by experiment I guess.. and gravity would drop it back to cover the port when the air is removed and this should suffice to hold the vacuum in your system. .. 
Now I'm referring to some type of disc covering a port for expelling air from the system but using gravity to hold it place and let vacuum form...
It would have to be something you'd have to figure out how to make. ..but a little imagination and I don't see why not 👌

mattmia2

reggi said:

Interestingly enough and overly simplified as far as total engineering of the unit but on the Richardson type air expeller for example there is a port exposed to the atmosphere that has a hinged weighted disc ( like a vertical swing valve) on the body of the expeller that opens to let pressure out ( the weight of the disc could determine it's cracking pressure, by experiment I guess.. and gravity would drop it back to cover the port when the air is removed and this should suffice to hold the vacuum in your system. .. 
Now I'm referring to some type of disc covering a port for expelling air from the system but using gravity to hold it place and let vacuum form...
It would have to be something you'd have to figure out how to make. ..but a little imagination and I don't see why not 👌

The issue is that just the weight of the disc is too much pressure to move the disc (although a disc with a larger percentage of the disc inside the system would take less pressure to move. Ideally the pressure to open it is 0. Maybe some sort of a paul type system where all the one pipe vents come back to a blower that can draw a vacuum on the system and open the check valve.

reggi

mattmia2 said:

Interestingly enough and overly simplified as far as total engineering of the unit but on the Richardson type air expeller for example there is a port exposed to the atmosphere that has a hinged weighted disc ( like a vertical swing valve) on the body of the expeller that opens to let pressure out ( the weight of the disc could determine it's cracking pressure, by experiment I guess.. and gravity would drop it back to cover the port when the air is removed and this should suffice to hold the vacuum in your system. .. 
Now I'm referring to some type of disc covering a port for expelling air from the system but using gravity to hold it place and let vacuum form...
It would have to be something you'd have to figure out how to make. ..but a little imagination and I don't see why not 👌

The issue is that just the weight of the disc is too much pressure to move the disc (although a disc with a larger percentage of the disc inside the system would take less pressure to move. Ideally the pressure to open it is 0. Maybe some sort of a paul type system where all the one pipe vents come back to a blower that can draw a vacuum on the system and open the check valve.

Maybe I was thinking oversimplified as the weight of the disc would have to be light enough to open to let out the air but heavy enough to close under it's own weight when the air is out,  of course that's where gravity comes in , and the resistance on the hinge is short as in the video it lets out wisps of air at a time and doesn't stay open for any length of time longer than another.  ... And that's the only vent to atmosphere on the system....( But there's more parts inside, just thinking how gravity could be your check valve)

https://youtube.com/shorts/pVFQoyk-lJU?feature=share