High pressure PRVs

Replies to This Discussion

Permalink Reply by John Norman on January 21, 2009 at 6:47pm

Tom,
Scaling is absolutely a critical concern with SP ops with fog nozzles. I have seen them shut down entirely by rust and crud. The initial flows often look like crude oil. I would avoid this option at all costs. Smaller hose will increase the FL, and depending on the length of stretch, 165 psi may not be too terribly high. 200 ft at 180 gpm requires approximately 150 psi with a solid tip, so you are in the ball park. This flow is likely to suffice for many residential fires, but of course, it is too low for serious fires in any occuppancy.I would suggest a screw gate with a pressure gauge downstream.


Tom Hofland said:

Chief,

Considering the nature of these PRV’s what are your thoughts about making the best of them? Does a fog nozzle make sense? Or is introducing friction into the system a better option?

Is scaling or restricting volume a greater problem in your mind? I know these are not ideal trade offs but they are my reality. Another option might be the use of a smaller (high friction loss) hose to flow high volumes through a smoothbore tip? (Greater than 200 gpm through a 1.75” line and an over pressurized smoothbore tip?)

If such high flows were expected through the small line a large play pipe is probably needed to reestablish laminar flow at the discharge orifice. I am not sure how/if this would work or effect stream pattern and reach.

Tom

Permalink Reply by Mike Walker on January 21, 2009 at 7:16pm

Isn't it great to have so much experience in this group? Thanks for your insight Chief, it is tremendously appriciated.

Tom,

Does your department currently use any type of in-line pressure gauge for Standpipe Ops? If so, what?

Permalink Reply by Tom Hofland on January 27, 2009 at 7:09pm

Mr Walker,

Seattle does not currently use an inline gauge during standpipe operations. However they have recently been added to our "minimum inventory" for engine companies so we are making progress. What is on paper and reality are not the same thing in my world but signals the long term goals of those with interest and energy but not rank.

We have an amazing training captain who is bringing Chief McGrail to lecture at the academy. I think it may spur some thinking about how we operate.

Tom

Permalink Reply by Mike Walker on January 27, 2009 at 7:25pm

Chief McGrail performed miracles when he spoke for my department recently. He is extremely convincing. Good luck brother.

Permalink Reply by Russ Chapman on February 6, 2009 at 4:35pm

Art
Check out Kochek. I heard they are working on a one piece built elbow with a built in gauge. We use their inline gauges as they are less expensive and beefier than the others. We have 90 degree light weight 2 1/2" elbows, and they both work great.
I hope more of the brothers are starting to use the inline gauges. I did an article 3 months ago in FE. If anyone here does not know what they are for, check it out.
Be safe
Russ

Art Zern said:

Les,

Great response. Are you aware of anyone who makes longer 60 degree elbow with a gauge? I have been looking for the elbow with gage, so far no luck.

Again great response and good advise on Dave's writings. I would recommend Dave's book Firefighting Operations in High-rise and Standpipe Equipped Buildings.
Thanks,

Art

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