Steam PRV Station

Jim123

I have scrolled through some of the pages of postings and didn't see any that would help me.  I'm designing multiple master details for a steam pressure reducing valve (PRV) station that the engineers at my office could use for their projects.  Problem is, I'm semi retired and have given away all my reference material (Sarco Handbooks, etc) and my reference library that included steam system articles from trade magazines over that past 40+ years.

Here are my questions:

For what inlet pressure should just a single stage, single valve  PRV station be used for 15 psig low pressure?

What about for a single stage PRV with 2 valves?  What leaving pressure should the valves be set at?

Same questions as above but for a 2 stage PRV station.

Thanks for any advice offered.

jumper

steam to steam

You may find that a steam to steam generator has advantages over a steam pressure reducing station. The former is simply a heat exchanger with controls on the motive steam.

Jim123

Steam PRV Station

Jumper.  The steam-t-steam HX is a good idea.  I still need advice as to my original inquiry for a PRV station.

jumper

pressure reducing station

Jim, I don't understand your question . You can't simply crank down on a valve to reduce pressure. A steam pressure reducing station has to first control the amount of steam and then expand that steam to lower pressure. Sometimes it pays to use a heat exchanger to superheat the low pressure steam and then flash the cooled high pressure steam to low pressure. Not an off the shelf project. You may try PickWaterHeater or LeslieSteamValves for help.

Steamhead

You should get in touch with Spence Engineering

their steam pressure regulators are very common, at least in our area. We use them on buildings connected to the local district steam grid:



http://www.spenceengineering.com/spence/Regulators.cfm



Spence also owns the Nicholson commercial/industrial steam trap line, so you might be able to deal with a single source on this job.

Dave in QCA

Fisher Controls

Fisher Controls make some excellent products. Check out the website, it has some good information that might help you. http://www2.emersonprocess.com/en-us/brands/fisherregulators/steam/pressurereducing/multi-purpose/92b/pages/92b.aspx



http://www.documentation.emersonprocess.com/groups/public/documents/instruction_manuals/d100703x012.pdf



Back in my day as facilities mgr at a hospital facility, we had several PRV stations to reduce the boiler pressure (70 psi) to space heating pressure, 10 psi. The high pressure was necessary to operate sterilizers and a few other pieces of equipment.

There were three building sections that were fed steam at lower pressures. Two of these areas utilized a 2 valve parallel flow Fisher Pressure reducing valves. They were set up as 1/3 -2/3 capacity and when finely adjusted would maintain a downstream pressure within 0.5 psi of the 1 psi set point. The valves were not new when I arrived and functioned perfectly during my 17 years on the job, without any failure or difficulty.

There was also a building that had a Boyleston brand PRV. It was a one stage valve and while it funciton satifactorily, it was prone to drift of 1-2 psi. In our case it did not cause a problem, providing steam for coils in air handlers as well as a few unit heaters. There also was a smaller Boyleston PRV that provided 25 psi steam to the kitchen for steam kettles, steam ovens, etc.



My experience in our midwest area, you can't beat Fisher Control.

Jim123

Steam PRV Station

I've been in touch with the local Sarco rep and he was most helpful of getting me PRV piping diagrams and advise as what pressures to set the valves.  Preparation of master details is underway.  The Fischer Controls Model 925 is our basis of design specification.  Thanks to all that provided response and input.

jumper

commercial steam is interesting

This thread reminds me why commercial steam is so interesting. Jim has reasons to use valves to reduce pressure. Others decide to use steam to steam although that involves two separate condensate handling facilities. Still others let steam go to waste. They all have their reasons. Laymen don't want to understand why the world is so complicated.