renosteinke

Emormous shunt trip CB connected to flow switch?

The disconnects serve assortes electrical panels located directly underneath. This is actually the main service for an older shopping center

As a side note, this place has been remodeled and expanded so many times that the panel directories contain numerous "identifications" as "Unknown" and "if anyone knows what this is for, please let maintenance know."

I would have thought that Halon or CO2 would have been required there.

Personally I would have set aside some maintenance time so that the buss could be deenergized and that sprinkler head capped.

Scenario: Electrical fire in the fry-daddy aisle, sprinklers go off.

Supervisor; "Johnny go turn off the electrical power, it's by the wall over there."

Now there are two fry-daddy aisles with electrical fires in them.

What's the average activation temperature of these sprinkler heads? I was under the impression that the fusible link/glass bulb in most heads wouldn't fail unless the fire was just about directly under them. That is, they needed a whole lot of heat. If it gets to that point, isn't that bus duct already gonna be compromised?

-John

I have seen a glass-bulb type trigger point as low as 155 F.

Ceiling temperatures skyrocket rapidly in the event of a fire. I've seen demonstrations where they were over several hundred degrees in minutes. Unless there was a large amount of ventilation in that room, the sprinkler would soon go off in the event of any real fire.

Don't know about old buildings, but the ones we do with backflows and PIVs are designed so that when the fire department shows up they select the building on fire and pressurize it up to 200 PSI. This results in all the sprinkler heads in the building going off. They might get a nice secondary explosion here =\

Though they are supposed to turn off the main when they show up, just don’t know if they do it before or after they set off the whole sprinkler system.

I am sorry I really have to question that, I think you may have been given incorrect info or misunderstood the info.

That is what happens in the movies, I have worked a lot of commercial buildings and have never seen a sprinkler system operate in that way.

The FD may very well turn on fire pumps but I doubt highly that causes all sprinkler heads to let go.

Two problems with that.

1)You would be basically 'wasting' your water supply and your main would have to be sized to run all heads at the same time.

I doubt a sprinkler main can support all heads open any more than our service main can handle all circuits fully loaded.

2)Insurance Companies. As much as the insurance company wants the fire out they definitely do not want water damage in the entire building for a localized fire.

I've never seen em do that in the movies, this is how I've been told they do it by the sprinkler guys.

I do a lot of multi building tilt ups. There is a main sprinkler line that goes onto the property to the backflow, from there it splits off to a PIV (Post indicator valve) for each building. What I have been told is that when the fire department shows up, they shut off the PIVs to all other buildings on the property and then hook their engine up to the system. The backflow prevents the pressure from going back to the main feed off the property. This then results in the heads of the buildings going off.

From what I have been told, the fire department's lowest priority are the contents of the building. Saving lives, preventing spread to other buildings is their primary concern, followed by saving the structure currently on fire.

As I am sure you have seen, even one sprinkler head going off can basically destroy the contents of a small-medium size building. Let alone what the smoke and fire will do.

I am sure other buildings are different, but this is how I've been told it works for tiltups.

I agree with the back flows and PIVs and hooking up the trucks.

The back flows have to do with not contaminating the city water supply.

I still strongly disagree that any sprinkler heads will open like a pressure valve when pump pressure is applied.

I really think you have been mislead.

Bob

That may be Bob, my only real concern is providing a conduit to the PIVs and the DCs

I see that a short "primer" on sprinkler systems is required.

Your "standatd" sprinkler head id set at 165F, and spaced to cover 144 sq. ft. Specific site considerations will result in a closer spacing, and the heads are available in different temp settings from 135 to 190F.

A fire heat plume- one of the standard tests uses a simulated wastebasket full of milk cartons- will very quickly elevate the temperature at the ceiling -over the entire room- WAY above the operating temp of the sprinkler head.

Sprinlker heads are also teated to excessive pressures, both sustained and surges. The idea that the fire pump will cause all the heads to "pop off" is absurd.
Now, there are "deluge" systems, where the heads have no trigering mechanism, but are left open and the pipes 'dry', that have all the heads operate at once. In this case, the water flow is triggered by a separate control. This is a system used in a few unusual situations- not your typical department store.

Different fire departments have differing ideas as to how fires are best fought. One of the indicators of a departments' competence is in the local fire insurance rates. Those who believe in standing off and throwing a lot of water at it have much higher insurance rates.


That a sprinkler head might be capped off for any reason just isn't going to happen- push comes to shove, and we get to move the electric.

Now, some will assert that water is a poor conductor, and that my concerns are unfounded. Others will point out the outside main disconnect that will allow the FD to shut down the power before entry.

Now, what if the sprinkler head were located below the duct? Maybe there is a role to be played in designing areas "outside" of sprinkler coverage. This, of course, flies in the face of a century of desinging sprinklers to cover everything, evenly, all the time. In any event, having the head that close to the duct can't be good for the spray pattern of the head!

As for the bus duct- I don't work on them that often, but here are a couple questions:
- Are 'filler plates' generally made to close off the sides?
- Is it generally possible to change a bus to be "right opening" rather than "left opening?"

This installation also brought up a few more issues, which I will raise in future threads.

[This message has been edited by renosteinke (edited 07-13-2006).]

Interesting comments John,
My understanding of connecting the output of a Fire Appliance pump to a building at a fire-call is merely to "charge" a dry-riser system within the building, this is then connected to a riser pack (2 lengths of hose and a nozzle) taken into the building by the first fire crew, for use, should a fire be found.

I have seen many deluge systems in theaters. The design concept being that if the building goes up in flames, you soak the curtains and everything on stage. I have never heard of pressure activiated sprinkler heads, but, I have heard of them failing. One randomly went off in the lobby of a television studio I was working in a few years back. Even the insurance inspector was surprised.

John,
If you are talking about the ISO ratings that insurance companies use to set rates, I will have to disagree. While the ISO rating looks at a lot of things to arrive at a classifiaction for fire departments, the strategy and tactics used by the department is not part of the rating. About 50% of the ISO rating score is from the water supply that is available to the fire department. The ISO ratings go from Class 10 (no organized fire department) to Class 1. There are only a few (less than 50, I think) Class 1 rated departments in the US.
Don

Mike,
Here, there are often fire department inlets to the sprinkler system so that the fire pump can be used to boost the pressure and flow to the activated heads. Often there will also be a dry riser system in addition to the sprinkler system.
Don

I work in locations that have wet and dry sprinkler zones and a deluge system. I could see cases where a sprinkler could go and result in other heads going, not from heat.

Consider a dry zone near a garage door. The riser has an air over water flapper valve where a given air pressure on top will hold back 4 times (or more) the water pressure. If your compressor fails or you develop a leak that the compressor can't keep up with, the flapper will release. Weak sprinkler heads, perhaps the ones that were leaking air, would now be spraying water.

Some wet zones also have flappers to allow a lower water pressure to hold back a higher pressure water source.

Our deluge systems are usually fired by heat detectors and pull stations mixed on two zones, triggering a solenoid to release the deluge valve There are no sprinkler heads, just flow nozzles.

Any of these flow events drop the pressure in the system more than the low volume jockey pump can make up for. The Jockey pump start pressure is the highest, followed by the electric, and the diesel fire pump being the lowest. Once the electric or diesel fire pump kicks in, the pressure pulse can wreak havoc with weak links in the system. I have seen broken fittings and pressure relief and check valves fail.

Our Fire Department siamese connections are for the fire fighters to connect to our high pressure side as their source. We do use dry connections in the subway though.

Finally, we do periodic testing of portable generators on a load bank. This is usually done just outside a building. One day it started raining so they pulled the gen and load bank just inside the garage door. They didn't notice that they had positioned the load bank directly underneath a sprinkler head. They found out shortly.
Joe

[This message has been edited by JoeTestingEngr (edited 07-13-2006).]

Yeah, ok. This never happens. Sprinkler heads rarely to never fail like your describing. First of all, sprinkler heads are normally UL listed to 175psi. The entire system is pressure tested at 200psi for two hours. FM has found that the chance of a sprinkler head failing is one in 16 million.

A properly designed and maintained sprinkler system will not break fittings, and how exactly does a check valve fail? Even if it did, it wouldn't harm system performance.
Haha, ok. Do load banks reach over 155 degrees f?


As for the actual head in that area, unless its within 3' of an electrical panel, there is no code violation. If that was an electrical closet, then the sprinkler should have a flow switch and a shutoff valve in just in case. There is no other requirements, except that the sprinkler line isn't allowed to run into and out of the room.

Think about it here guys, there is an extremely limited chance of that sprinkler head accidentally going off due to mechanical failure. In a fire situation any damage from water is going to be small potatoes compared to what the fire is going to do; even with electrical components.

[This message has been edited by DerBlitzkrieger (edited 09-09-2006).]

DB, a "load bank" is nothing more than the biggest toaster you'll ever see. Lots of elements, getting red-hot. It is quite possible for an area near a load bank to get too hot.

Of course, if it does.... well, that's what the sprinkler heads are for. There are heads made with temperature ratings as high as 195 degrees.


I.m still not convinced that spraying water - even in the case of a fire- on an exposed high-amperage buss is a good thing. That's why I posted this pic!

Der-
I agree that the odds of failure (IMO) would have to be designed to be impossibly low. However, the 175psi you quote seems low. My building has the siamese needing at least 176psi for top-floor demand (to check, I found a pressure guage in a stairwell reading 176psi at standby). Were you saying at least 175, or ... ? Just needing clarification, thanks.

Hello Der & welcome to the forum!

You're a sprinkler designer and I'm not so the only counter I have to your statements would have to be:

103rd Bus, Howard Rail, and West Shops.

Our house electrician saw a shadow on the wall where the sprinkler in the dry zone was leaking. I observed it after repairs were not quite complete.

2, 10 inch check valves failed by crusting up inside. This caused leakage back through the electric and diesel fire pumps that they followed. This caused short cycling and ultimate failure of the jockey pump. This caused running of the electric pump with high pressure bursts of water dumping into city drains. The city of Evanston would dispute your claim that system operation would not be adversely effected.

I wasn't there for the load bank incident but I have no reason to doubt my fellow engineer who was.

Now I admit that I'm not a big fluidics guy. I've personally observed hammer effects in diesel fueling and fire protection systems that I can't quite make sense of. I try to equate it with resonance but that only gets me so far.
Joe

Hello gentlemen. Yes, I am a fire sprinkler system designer by trade. To give you a little background, I have been working in the industry for five years, and I have a NICET III in sprinkler system layout, and a level II in special hazards systems.

I dabble in some low voltage work for special hazards systems, like Sapphire, FM-200, and other clean agent systems. Its all A&D work, though. My only involvement with high voltage systems would be electric fire pumps, and even then, most of that is handled by a note on the print saying "all electrical connections by others." But, I enjoy reading EC&M magazine, and try to learn a little bit when I can. Sometimes I wish the NEC was laid out like NFPA 72 and 13, because the article layout is sometimes hard for me to follow.

Anyway, moving on to your questions and responses...

renosteinke:
Ok. I didn't know what a load bank was, but I had a hard time believing that it could to that high a temperature if there are people working around it, and moving it. But hey, if you say it gets that hot, then I will take your word for it.

As for sprinkler head temperatures, they actually go a lot higher than 195 deg F. Standard temp is 155 deg F, but you can get certain sprinkler heads for very high temp applications up to 650 deg F. They aren't very common, though.

trobb:
The 175 psi is the normal max pressure on system components. If a system doesn't have a fire pump, you normally aren't going to see anything this high for a system working pressure. The nature of the wet system clapper means that it opens up under water surges. This extra pressure gets trapped in the system when the clapper closes, and that is why you will sometimes see a higher pressure on the system side of the check valve.

176 PSI isn't that unusual, especially on a standpipe system where you have very few places for pressure to leak back, and I'm sure you know that there is always some percentage of error inherent in gauges. 176 PSI on the gauge is probably more like 173-177 in reality. Now if it was 275, yeah, I might be concerned.

As for the pressure requirements for the standpipe at the FDC... I'm not really sure what you're trying to tell me here. Its probably a terminology issue, though. What kind of building is it? How tall is it? What size fire pump does it have? Your insurance company may have required a higher working pressure at the standpipe outlet than required by NFPA 13 (100 psi). If the system is supplied by a fire pump, and it is an automatic wet standpipe, it shouldn't need anything from the fire department to meet that 100 psi requirement. Now, keep in mind that that is 100 psi at 250gpm flowing. Water pressure degrades with flow, so your 176 static may go down to 100 at the flow required for the standpipe flow, and that depends on your water supply.

JoeTestingEngr:
How does a leaking sprinkler head create a shadow on the wall? Was the sprinkler subject to mechanical damage at all? How old was the system? There are a lot of variables. Was this in a very cold area? Was it a dry head on a wet system? There is too much info missing for me to say what happened, obviously. And of course, I'm not going to claim that no sprinkler has ever leaked, that would be foolhardy, and not true. Its rare, though. I'm more mystified about the shadow thing!

Was regular maintanence performed on those check valves? If so, that much crust in a years time speaks highly of Evanston's water supply system. Maybe a strainer would help out a bit. Was there a backflow involved with this installation as well? Also, there are normally issues with discharging PRVs into public sewers. I would love to see this fire pump installation. Also, are the pumps in series or parallel?

"Haha, ok. Do load banks reach over 155 degrees f?"

Easily. I saw this happen as well where a load bank was parked in a sub basement next to the generator room.

Der,
Suppose you put a nozzle on an air line that hadn't had its separator drained recently. If you directed it towards a nearby wall and opened it slightly, I don't think it would take long to see a deposit build up. I think that is what our garage electrician saw on the wall near the sprinkler head. I was just there fixing the XL3 system when he told me why I had a supervisory on that zone. A contractor did alot of other work before listening to him and replacing the head.

The 2 check valves probably hadn't been checked in years. The pumps are in parallel. I was there because they suspected a leak in the yard as a cause for the jockey short cycling. But when I gated off everything coming off the manifold, we were still losing pressure at the same rate. That's when the check valve became suspect. We gated off at the source to verify. They come in to run tests on both fire pumps but I'm not aware of any specific tests on the check valves or required maintenance on them.
Joe

A further posting about the sprinkler mis-conceptions. We service and repair sprinkler systems, but do not install or design sprinkler systems. We also install, upgrade and service chemical fire suppression systems.

The fry daddy and other cooking appliances are required to shut off the fuel source when the fire suppression system trips. The elecltrical shut-off can be a contactor or shunt trip breaker. The power shut off may be at the extension cord, or at the panel or anywhere in between. My personal preference is at the panel.

The standard sprinkler head is rated at 155° and if a glass bulb will have a red liqued in the glass bulb. Other colors denote higher temps, w/a 450° head being the highest temp. NFPA 13 calls for a head rated at 25° over ambient temperature. If you see a leak or discoloration at the sprinkler head, call a sprinkler contractor to do an inspection. Kind of like we call in an electrician if we see discoleration at an electrical fitting.

The accepted industry statistic for sprinkler head failure (leaking head) is 1 in 6,000,000.

Pipes and fittings do leak, but not normally. Pipe and fittings are usucally rated for 175PSI working pressure,and are pressure tested at 350 PSI for a certain length of time. Usually the leaks we see are in Schedule 10 pipe and grooved fittings in dry systems.

The connection the fire truck connects to are called Fire Department Connections, or FDC. The purpose is to support the sprinkler system by insuring enough pressure and volumn of water. That big truck is just a big pump, often pumping 1750 GPM or more. The standpipes are also supported by the fire department. Fire departments use there own hoses on the standpipes, not the hoses found in the building. Fire departments are very distrustful of the condition of the rack hose in the building. Even with testing, fire hoses will rupture. The rack hose in a building is an unknown item.

Douglas Hicks
General Fire Equipment Co of Eastern Oregon, Inc