What is this valve

MacPHJr

Saw this valve in the piping system for a steam boiler at a school. Never saw one before. Anyone knows what it is used for. It has a manual lever, but its not usable because someone ran a copper heat line in the way.

Tom bates

What is this valve

HI, I seen a valve that like that on a set of 1942 drawings it is called a "pressure reducing regulator". I will try to dig up more information in my archive, If i find anything I would post.

What is the age of the school? What is the pressure the boilers operate at? and can you take more photos of the near by piping / boiler room?

Steamhead

It is a pressure-reducing valve

which raises the question- why is it there?



If part of the steam system runs at a lower pressure, as for heating rather than process work such as kitchen or laundry equipment, this valve services the lower-pressure part.



It also may be part of a differential-vacuum system like the Dunham Vari-Vac. In that type of system, a vacuum pump would pull a vacuum on the steam side as well as the return side- all the way back to the PRV. The level of vacuum determined the steam temperature, and you could manually or automatically adjust the valve according to the outdoor temperature.



Is there a name on the valve?

MacPHJr

Low Pressure Steam Boiler

Its connected to a low pressure steam boiler that is used to heat a dormitory that was built in 1931. It looks like they added a bypass to it, so at some point they may have been running higher pressure boiler. The boiler is a two pipe system with steam traps on mains and radiators.



We are there to replace the water main. Just curious to what this type of valve would be used for.

MacPHJr

Upside down

Is this valve upside down? It looks like it is according to the schematic posted.

Steamhead

If there is or was a vacuum pump on that system

then that valve was used as part of the vacuum regulation system, as I described above.  

Tom bates

What is this valve part 2

Hi, I researched my archive of drawings a bit more, and i found a valve that is very close to the one in the photo.

The previous drawing I posted if for a large industrial heating system, the valve reduced 215psi steam down to 115psi, that was distributed to PRVs near the steam coils. The PRVs at the coils reduced the 115psi down to 10psi in each of the 30 fan rooms. There was also a 100psi large paint room steam coils, in which the condensate was flashed and the 10psi steam was used for heating in neighbouring buildings.

I found a drawing of a 1951 school with a vacuum system, The steam comes from the boilers at 10psi and is reduced to 5psi. I am not a expert on but I assumed vacuum systems did not operate above 1psi some times as low as 5oz, if this the case, why did this system use 5psi steam with vacuum?

Tom - AKA the blueprint guy

Steamhead

If they just used vacuum in the returns

then the steam side could run at whatever pressure. But on the one in your photo, I have a hunch both the steam and return sides were under vacuum.

MacPHJr

Did they change system types

I can ask the facility manager, but would the previous contractor (40 years ago) have converted a vacuum return system to a gravity return system? What would be the advantages of doing that? They are proposing a new boiler for next spring. The new system will have condensate receiver with boiler controlled pump.



The existing boiler looks like its piped incorrectly, It looks like it has a double header. Two riser come off the top of the boiler with swing joints into a 3'' header. Then there is a 3x4 bull head tee with a 4'' riser to another 6'' header. There are 3 steam supplys off the 6'' header. Doesnt look right to me.



Can you do a drop header on a boiler this size and then pick up the three mains separately? I will try to get some pictures next week.