Pressure reducing valve

[Cidona]

This site was just recently recommended to me and I am very happy to see the level of experience and knowledge in the posts.
With that said, I’m hoping I can get some advice on the correct direction to take with a situation I’m dealing with on a project I have.
The building is a new construction, 3 story, commercial property. Approx 28,00sq ft/ floor. Originally the project did not have hose valves included in the scope of work. The pump (installed), fed from an above ground tank, was sized for the sprinkler hydraulic calc areas. We ended up with a 110psi @ 1500 gpm. (ESFRs drove the calc).
Now we are required to provide 1½” FHVs in accordance with NFPA 13 2007, Section 8.17.5. We have 4 – 1½” FHVs (in the ESFR areas), and we are also providing 1” stations which are desired in addition by the insurance company
The calculation procedure required is outlined in 12.8 and is not required to have the 65/100 psi pressures required by NFPA 14. The hose demand is only required to be to be added to the beginning at the most remote station with each increment added at the pressure required by the sprinkler system design at that point.
The static and residual pressure on the hose line is restricted to 100psi. So we were going to use a pressure reducing valve to bring our static pressure down. I have not worked with PRVs before. I was thinking of using a 2½” Potter Roemer 4036 in an in-line installation to supply all the hoses , but after reviewing the valve it seems once the pressure on the inlet side of the PRV drops below the outlet static setting that there is a large ‘friction loss/pressure drop’. With not having a required pressure (other than having the pressure at the point of connection to the sprinklers) in the calc, the pump provides limited pressure at the hose under a flow situation (i.e. well below the outlet static setting 100psi)). To reduce it further doesn’t seem to be in good fire protection practice. While the static is in breach of the 100psi requirement, once in a flow situation the pressure is going to be less than that and would seem to be a preferable situation than complying with the static and dealing with the drop in pressure when it would be being used.
The individual 1½” PRVs seem to have the same problem.
The Tyco PRV-1 (pilot operated) also has the same problem.
So, I was wondering if anyone has come across this type of situation before. Any suggestions on products or solutions would be greatly appreciated.
Also, just to sneak it in here while on the PRV topic, when would you use a pilot operated PRV instead of the simpler (presuming less expensive) ‘regulating spring as part of the valve’ type offer by Potter Roemer/Zurn?
Thank you for any input. Sorry it was so long.

 

[stookeyfpe]

From what I read the hose valves are not required. If it is a 3 story building in the US, standpipes are not required by the International Fire Code. And I somewhat confused in that you have a 3-story building protected by ESFR sprinklers.

Is this a warehouse with a multiple level of offices housed in mezzanines? Regardless, I don't think NFPA 14 applies.

 

[Cidona]

Thank you for the reply stookeyfpe. The building is as you mentioned, a mix of offices and warehouse areas. We do not need to comply with NFPA 14 but rather NFPA 13. NFPA 13 (Section 8.17.5) says that the hoses are not required unless required by the AHJ which in this case is the Insurance company. They want the hoses. The property is in Europe but they are using NFPA 13.

 

[FFP1]

Talk with the local fire department (preferably the Top Dog) and ask them if they want small hose stations or would even use small hose stations during a warehouse fire incident. Be prepared to show them the location and availability of fire hydrants. In many instances, they will tell you they do not even want small hose stations or only use small hose stations as a last resort.

If this is the case, ask for a letter outlining their position. Using this letter and good communication skills, you will probably find it realtively easy to obtain a "deviation from standards" from the insurance company.....resulting in a warehouse protected by ESFR sprinklers with no small hose stations.

Good luck!

 

[Cidona]

Thanks but the pipe to the hoses is already installed (we had been presuming we had the PRV option). The insurance companies seem to have more of a say over there and this was a definite requirement. It seems less buildings are required to have sprinklers per code than here (US), and the ones that do get sprinklers do so for insurance reasons. The drawings, calcs etc were reviewed by the insurance company and they want the hoses. As mentioned the hose pipe is installed and the project is looking to close up shortly. The change for the hoses requested by the Insurance company has already gone through the procedures required for additional work (pain in the rump). If there was a feasible solution, we were hoping to be able to comply with their requirements. Thank you.

 

[cdafd]

If you only have to provide the hose stations, and do not have to meet nfpa 14, than

1. do you also have to provide hose with the outlet?

2. or do you only have to provide the outlet??

3. where do you get the "The static and residual pressure on the hose line is restricted to 100psi." from??????

4. what I am getting out if there is no design criteria than can't you just provide an outlet and every one is happy, and maybe throw in a pressure gage at each outlet, that way you just choke down the valve to desired pressure?????

 

[TravisMack]

Cidonna:

Like CDA said, there are a couple of things I can think of:

1 - You could use "pressure regulating" valves, not pressure reducing valves. These basically throttle the flow. I have seen these used in systems where the pressures exceed 100 psi. That would save you the hassle of factory or field set pressure reducing valves

2 - These small hose stations need to be supplied by an adjacent system or separately valved on the riser. Therefore, you are only added the supply to the the "bigger pipe" on the job. So, it "shouldn't" really impact the underground or riser sizes, unless you are calc'd pretty tight. I have just added 50 gpm for each station in / near my design area. So, basically, I may have an extra 50 - 100 gpm that is added at the base of riser or in the underground line. We then add the additional hose allowance to get to 250 gpm for an ESFR system.



CDA:

From NFPA 13, 2002: When the pressure at any hose station outlet exceeds 100 psi (6.9 bar), an approved device shall be installed at the outlet to reduce the pressure at the outlet to 100 psi (6.9 bar).

 

[cdafd]

TravisMack


From NFPA 13, 2002: When the pressure at any hose station outlet exceeds 100 psi (6.9 bar), an approved device shall be installed at the outlet to reduce the pressure at the outlet to 100 psi (6.9 bar).


is that also in nfpa 14????

 

[Cidona]

CDA.
The hoses are to be in accordance with NFPA 13, 2007, section 8.17.5. It is phrased as 'hose connections' though we are providing FHR in cabinet.

1. We are providing valve and hose in cabinet.
2. We are providing valve and hose in cabinet.
3. NFPA 13, 2007, 8.17.5.1.4 (5). It is also part of the commentary in the 'Automatic Sprinkler Handbook 2007'.

There is design criteria. Hoses per 8.17.5 and added to sprinkler demand per 12.8.4.
When you speak of choking down the valve, are you meaning reducing the static pressure on a PRV? The problem with reducing the pressure (static setting) on the PRV is while that is all and good when in a static condition, however when there is flow, the and the inlet residual inlet pressure is reduced to below the static (100psi) there is a drop in pressure with the valve(20psi in cases). To reduced the static setting (eg 80psi) would help so long as the inlet didn't drop lower than that. If the sprinkler system was going off at the same time and the pressure was less than the 80psi, you'll loose the 20psi from there.
If you were intending something else by the 'choking the valve', please let me know.

Travis.
It was a pressure 'regulating' valve I was looking to use. The potter roemer 4036 and Zurn call themselves pressure regulating valves though they seem to be more like 'pressure reducing valves' as they reduce the static upstream pressure to a lower static downstream pressure and under flow continue to reduce the downstream pressure in ratio (graphs) to a lower pressure than the inlet. Rather than 'regulate' it at a constant pressure.
On the flip side, the tyco PRV-1 pitlot type (called Pressure REDUCING valve) provides a constant lower pressure regardless of inlet pressure (sounds more like a regulating valve than the potter roemer one to me). The problem with the Tyco one is once your inlet pressure falls below the outlet setting there are graphs showing a large drop in pressure. Also they are recomending having a minimum 50psi difference in upstream and downstream pressure to maintain a constant flow at the set pressure. Which I don't have.
The extra flow for the hoses (added at the point of connection) is not an issue for the calcs for the sprinkler system. The problem is when the sprinkler system (remote area) is flowing the pressure at the point of connection is less than it was at static. It is still enough to get 250 gpm to the hoses with 40 psi. However if the PRV reduces the pressure at the point of connection, there will not be 40psi at the FHV. More like 15-20psi (and that's at the valve, without the hose).
I'm including 250 gpm per the hose stream allownace in Table 16.3.3.1 (NFPA 2007).
If you had a different type of valve in mind please let me know.
I am trying to avoid some poor soul running in to fight the fire turning on the hose and getting a spurt followed by drip, drip, drip. A similar result from a test is also desired to be avoided.
Thank you all again.
PS Travis, you'll be sorry you turned me on to this site I'm going by 'Cidona' as Damien (VR Forum) was already taken here.

 

[Cidona]

CDA:
NFPA 14 (2003) 7.2.1 restricts 1½" hose to 100psi and other hoses (ie 2½") to a maximum of 175psi. In my area I have typically only had the 2½" and have not been required to reduce the pressure. But I would think that this would have also be a concern for thoses dealing with 1½" hoses per NFPA 14.

 

[TravisMack]

Sorry, I used the wrong term as well. A pressure restricting valve is what I was thinking:

Potter 4080: Used with a fire hose rack assembly or as a fire dept outlet connection. Water pressure is controlled by adjustable flow restriction. If full flow is required, the restriction may be overridden.

This should be able to make it a non-issue. This is the valve I have seen used in multiple places. This is pretty much the standard valve that I use when we have to put in 1½" hose stations for ESFR systems, or any system with a pump. All of the AHJs I have dealt with are happy with this valve.

Travis

 

[Cidona]

I had spoken briefly to Potter Roemer regarding the 4080 but it only provides 'adjustment to provide a range of the outlet pressures under flowing condition only'. See attached sheets. So doesn't help the static requirment. Liked the overridding feature though.

 

[Cidona]

Wasn't able to attach the file with the 4080 setting instructions which have the 'under flowing conditions only' statement. Anyone have previous problem uploading files and posible remidies to suggest (acceptted file type/sizes)?
I'm thinking I may appraoch the Insurance for an exception to allow the 4080 as breaching the static condition seems preferible to the residual and the restriction overridden feature would allow full availible flow if required.
Still curious as to what to do if required to comply to the letter of the law (ie Static also below 100psi)(this project or future).
Thank you all very much for your time and input.

 

[cdafd]

Oh!!!!!

Did not look at 13 or 14, jsut shot a suggestion oout.

What I meant by choking is like you would do with your home outside faucet, if you wanted less pressure or water than turn the valve towards the off position.

Not sure how they do it across the pond, but here alot of people are saying do not have 1 1/2 inch hose connections or do not put the hose on it, because they do not want jow average trying to fight a fire, and the fire depts bring there own hose if they want to use the connections at all.

http://www.ultimatefiresprinklerguide.com/

 

[Cidona]

cdafd.
Choking/throlling the valve will control ammount of flow you get out of the hose but wouldn't control what pressure that you would have at a given flow or in static condition. If you were to close the valve you would be reducing the flow while increasing the pressure. I was trying to comply with the 100psi staic and resideual requirement.
Like yourself I'm used to the fire department wanting their 2½" and not wanting joe fighting fires but in this case they wanted the 1½".
Thanks for the suggestion.

 

[DavidCR]

We only have a requirement on flowing residual presure, in addition to NFPA 14 we have a local requirement that residual pressure for 1 1/2 ocupant use hose (rack or reel)shall be 65psi for 100 gpm.

I don´t understand why you need 100 psi static.
In my experience:

I like 4080. The adjust graphs included with the valve are not accurate, in fact when we performed the setting in the field, we got other values (it is not really clear what is the visual indication of the seting point, the valve has a convenient indentation on the indicator, but the manual says other) so we decided to use the identation.

The setting in the field was performed with actual discharge with 75' hose, barrel gauge and a pitot. It is always advisable to have an override feature.
Things that I don´t like of these valves: they are not for though use, you can easily loose the override device (better secure it with a cord) and for pressures of 200 psi or more the handle can move by itself (tighten it).

I don´t like much 4036 as a direct hose connection. The handle is very hard to move, they don´t allow maintenance, and there is no override feature. (I´ve not performed the setting of the pressure yet so I don´t comment on it). I´d like to know if there are other similars that are softer.

Both 4036 and 4080 current Potter Roemer models are provided by an italian manufacturer: Giacomini.

Another convenient option is to use a comme hose valve with Potter 2765 restriting device.