Preventing Fire Outside from Getting Inside Repeater Vault

[BirkenVogt]

The Mount Diablo thing has me wondering how that box caught fire. It was either a semitrailer or a shipping container. If a trailer, was there a combustible exterior or underfloor? Did ventilation suck fire inside? Did it get exposed to enough heat to catch the insides on fire through conduction?

I would like to prevent any repeat performances of this.

http://www.arrl.org/images/view/News/MDARC site-1.jpg

 

[WayneH]

I've been up to North Peak enough to know it pretty good. That is indeed a shipping container and I forget what's elevating it off the ground. The "offline" remark could just be damage to the coax.

That's the only shipping container on North Peak. The two other buildings are true built shelters/buildings.

Most modern pre-fab shelters will shut off HVAC when the smoke detector trips. All the new Fibrebonds I've worked in have done this. Shipping containers on the other hand....good reason someone used them, because they're cheap.

 

[BirkenVogt]

I have been thinking along the same lines, that I would like to kill the ac if the smoke detector trips. But the question becomes, then what? It is going to start heating up fast even if there is no fire. If we cut the DC power due to over-temp, then we are hanging our entire revenue stream on a little temperature control.

I guess what I really need is a very reliable method of alarm transmission so we can go up and fix it if it false trips, or possibly 2 different ones. Any ideas on what works?

 

[WayneH]

I have been thinking along the same lines, that I would like to kill the ac if the smoke detector trips. But the question becomes, then what? It is going to start heating up fast even if there is no fire. If we cut the DC power due to over-temp, then we are hanging our entire revenue stream on a little temperature control.

I guess what I really need is a very reliable method of alarm transmission so we can go up and fix it if it false trips, or possibly 2 different ones. Any ideas on what works?

Did you see this thread in this forum about temperature sensors? http://forums.radioreference.com/industry-discussion/271481-temp-safety-cabinets.html

Batteries, since there should generally be either DC battery backup or a UPS, are a first concern. I don't know what temps inside a shelter would achieve with a fire outside but I once walked in to a shelter where both HVAC units had failed. The temp was pushing well over 110 deg. The batteries of course eventually failed. I found this out when the gen went to transfer on exercise; the batteries couldn't hold a load for a second.

If you want to remotely power off equipment I would look at web controlled power outlets. APC makes a line called the "MasterSwitch" if you want to source something used. Their most recent is the AP7900. http://www.webpowerswitch.com/ is another vendor.

 

[zz0468]

I've been up to North Peak enough to know it pretty good. That is indeed a shipping container and I forget what's elevating it off the ground. The "offline" remark could just be damage to the coax.

I've seen post-fire photos, and it appears that it's actually a trailer, not an all metal shipping container. It had wood sides on the inside, and a wood floor. Fire got underneath, and it burned from the inside out.

One end was gutted, with heavy smoke and heat damage to the other end. Most, if not all, equipment is a total loss.

 

[zz0468]

I guess what I really need is a very reliable method of alarm transmission so we can go up and fix it if it false trips, or possibly 2 different ones. Any ideas on what works?

How about a series smoke detector and high temp alarm. Both have to trip in order to remove power, and shut down HVAC. The problem with any such plan is, by the time heat and smoke are enough to trip sensors, the building is probably already on fire.

You could alarm heat and smoke separately, and use the alarms to notify someone to look at the web cam (your site DOES have a web cam, right!?) and take appropriate action.

The best thing to do is a block building on a concrete foundation with adequate fire clearance outside, and a fire suppression system inside. The shipping container comm site can be done nicely, with as many amenities as you care to put into it. You get what you pay for.

 

[jim202]

Is there any reason that the brush can't be cut back to reduce the heat load if there was a fire outside these sites?

I have been to a number of sites over the years and the grass, brush and small trees are right up against the fence if not inside the fenced area. This is like asking for your site to be burnt to the ground.

My next comment will irritate a number of site owners because they are either too cheap and use an old box trailer or took the site over in that condition. Then they are rolling the dice, hoping nothing would happen over time.

It just blows my mind when a site owner takes these risks and then complains when his truck trailer gets damaged from a fire or storm. Your getting income from your customers and your too cheap to provide a decent equipment shelter for them. Somethings wrong with this picture.

 

[zz0468]

Is there any reason that the brush can't be cut back to reduce the heat load if there was a fire outside these sites?

At the sites I run, on USFS and BLM property, that is a strict requirement. There is a 50' cutback requirement, and there is talk of increasing it to 100'.

I have been to a number of sites over the years and the grass, brush and small trees are right up against the fence if not inside the fenced area. This is like asking for your site to be burnt to the ground.

My next comment will irritate a number of site owners because they are either too cheap and use an old box trailer or took the site over in that condition. Then they are rolling the dice, hoping nothing would happen over time.

There are a lot of notoriously cheap site owners out there. Some of the largest corporate site operators are among the cheapest.

It just blows my mind when a site owner takes these risks and then complains when his truck trailer gets damaged from a fire or storm. Your getting income from your customers and your too cheap to provide a decent equipment shelter for them. Somethings wrong with this picture.

It IS possible to minimize expenses when developing a site. I've seen some container sites that are VERY nicely done. A container can cost a couple of thousand dollars, delivered on site. They're tough, and durable. But you have to do a whole lot more to it than just drop a box on the ground and pack it full of radios.

 

[WayneH]

I've seen post-fire photos, and it appears that it's actually a trailer, not an all metal shipping container. It had wood sides on the inside, and a wood floor. Fire got underneath, and it burned from the inside out.

It had the standard shipping container style doors. I would say it's a vintage version of something used to ship with. It may have even been attached to the frame of a truck at one point in its life.

 

[zz0468]

It had the standard shipping container style doors. I would say it's a vintage version of something used to ship with. It may have even been attached to the frame of a truck at one point in its life.

Makes sense to me. In the pics I've seen, it's clearly very old, with a higher content of wood inside than you'd normally see. Over the years, I've heard it referred to as a trailer, but you're right, the doors are clearly container style.

The big question for all the ham systems in there now is, will the owner replace it.

 

[mkewman]

Is there any reason that the brush can't be cut back to reduce the heat load if there was a fire outside these sites?

I have been to a number of sites over the years and the grass, brush and small trees are right up against the fence if not inside the fenced area. This is like asking for your site to be burnt to the ground.

My next comment will irritate a number of site owners because they are either too cheap and use an old box trailer or took the site over in that condition. Then they are rolling the dice, hoping nothing would happen over time.

It just blows my mind when a site owner takes these risks and then complains when his truck trailer gets damaged from a fire or storm. Your getting income from your customers and your too cheap to provide a decent equipment shelter for them. Somethings wrong with this picture.

Here in California, at least in the past, Fire Marshals will fine site owners if there is a fire hazard and it isn't taken care of PDQ.

It cracks me up that some of the big corporate site owners are the biggest offenders, when they have the most to lose when something likes this happen.

Anyone have a link to more of the diablo pics?

 

[slicerwizard]

It cracks me up that some of the big corporate site owners are the biggest offenders, when they have the most to lose when something likes this happen.

Reduced maintenance/payroll costs is management's most important yardstick (profit = revenues - expenses) - and managers' bonuses depend on it. These problems you speak of? Don't you know they're not a problem until they're a problem? And don't we have insurance to cover these occasional annoyances anyway? Think like a BOSS!