Halon

[tilwinter]

Just out of curiosity, I removed the halon unit from the engine compartment in my 1981 30+.

It has a date of manufacture of 1989.

According to the label, it should be weighed every 6 months to be sure it has enough halon, I suppose.

Any thoughts about this unit? Can I assume that the heat sensor still works after all these years. Is there someplace the sensor can be checked? Should I shell out 400 bucks for a new unit that has the halon replacement, on the assumption that it is more likely to actually work if there is a fire?

An engine compartment fire is obviously a serious concern.


Rod Johnson

 

[wanderer]

unless your engine compartment is airtight, i wouldn't use halon.

halon works on the principle of oxygen displacement so if your engine bay isn't airtight - and i've seen NO sailboat with an airtight engine compartment - dumping halon won't be as effective as most people think. also, halon has no cooling effects.

halon is very effective for fighting fire in the right conditions.. ie... a space that can be made airtight to avoid oxygen from entering and allowing the agent to do it's job once it's been deployed

as far as checking the unit, i'd look in your area for a fire saftey shop or your local fire dept. they'll have the info or contacts

personally, i'd go with a CO2 system for the engine bay and a foam agent system for your bilge

hopefully this helps

 

[HGSail]

I have a story about someone that I once worked with, He worked at our satillite facillty at the KABC Prospect lot. When a small fire broke out in the room ajacent to him the Halon system activated, He only had 25' to get to the door and he did not make it. 25ft!!! By the time he could react he was dead, That's how fast it displaces the air!!! The Halon had sucked the air right out of the room. As far as I know, These systems are no longer available to the public. Please look into another system, We wouldn't want to lose you to this nasty stuff.

Pat
E29
'73
#224
Holy Guacamole

 

[tilwinter]

Thanks for the thoughtful comments.

I read a lot on the web, and most of the comments about halon in boats were favorable as to efficacy, and there was little mention of potential toxicity as long as there was less than 5% halon in the immediate environment. I would not plan to be in the engine compartment. I am more concerned that my unit is no longer functional, and how to find out.

I gather the only reason it is no longer used, is concern re the ozone layer.

My inclination is to leave the cannister deployed and hope it never is needed. At the same time I will make sure there are adequate additional units available near the engine compartment, in case a fire occurs and the halon either does not deploy or is ineffective.

To replace it with a self-deploying CO2 unit is very expensive.

I wonder how many of the people on the board have a dedicated self-deploying system in the engine compartment?

 

[Loren Beach]

Our '88 model came with a factory Halon bottle system mounted over the front of the engine. I have the bottle weighed every few years to re-certify it. We have the standard green "ruby light" indicator which stays lit as long as the Halon release valve has not been heat-activated.

Our engine compartment is quite small, and diesel fuel seem like a low-risk fire hazard in a well maintained boat, IMO.

YMMV,

Loren

 

[Howard Keiper]

I have one of these units too, and my local fire extingusher re-fill place says they aren't allowed to recharge or certify them anymore. On the other hand, say they, if the pressure gauge reads in the green, and you can hear stuff sloshing around inside, then it's more than likely OK.
Anyway, if it doesn't go off when it should, I'm no worse off than if I didn't have it in the 1st place...no??
howard Keiper

 

[Shadowfax]

I thought they where banned about 7 or 8 years ago. I doubt you could buy one now, if that is in fact true

 

[Loren Beach]

Halon fire bottle OK here

I just got off the phone with the local fire extinguisher company that I take my stuff to for checking and recertifying every few years. They didn't even hesitate about having me include my Halon bottle for weighing and re-tagging.
I do understand that once emptied, it cannot be refilled with the same stuff...

And that's the news from Portland, OR

Loren

 

[tilwinter]

The interesting comments continue.

Do any of you engineering types out there have any idea as to how the heat activation works? Does it become innactive due to corrosion over time?

 

[wanderer]

The interesting comments continue.

Do any of you engineering types out there have any idea as to how the heat activation works? Does it become innactive due to corrosion over time?

in the nozzle, horn, sprinkler head, there is usually a glob of solder or a bulb of water which keeps the valve closed. upon reaching a specified temp (usually from fire) the solder melts or the bulb bursts opening the valve.

as far as innactivity, the concern is over time the agent will cake up in the cylinder via humidity and gravity.

any dry agent extinguishing system can fall victim to that, hence the inspections

unfortunately, i know too much about shipboard fires

the nicest thing about halon is it's very easy to clean up and doesn't damage equipment

 

[Captron]

The problem with halon and CO2 for that matter, is that while they will suppress a fire, they do nothing to eliminate heat or neutralize fuel ... often, once the fire is out, it will reignite once oxygen is reintroduced (or leaks in) unless other steps are taken to eliminate heat or fuel. Fires require specific agents depending on the type of fire. Halon and C02 are at best fire suppression systems rather than extinguishing systems.

Dry chemical will extinguish a fire in wood, fiberglass, fuel, wiring, even metal fires if you can dump enough of it on. It will damage engines, alternators, and other mechanical gear though.

Foam is best on fuel fires but cannot be used on electrical fires.

Water will work on wood and plastic but is not useful for fuel or electrical fires.

Fog will work on fuel and ash producing fires but is not useful in fighting electrical fires.

IMHO, you would be better off to install a fire detection system and have a way to shoot lots of dry chemical directly on the fire. When it comes to dry chemical fire extinguishers, more is better.

 

[kevin81]

Some facts on Halon

A few items to clarify on the subject...
1. There were two types of Halon suppression gases - "1301" for occupied areas and "1211" for portable fire extinguishers. The fixed/automatic extingushing systems that were available for the marine industry were available in both 1301 and 1211.
2. Neither 1301 or 1211 extinguishes a fire by removing the oxygen. They work by stopping the chemical reaction that takes place in a fire. CO2 does work by removing the oxygen.
3. Halon 1301 systems were developed for occupied areas, i.e when designed correctly people would not be harmed if the gas was discharged into the space they are in. The design concentration is 5% to 7% by volume.
4. Both halon 1301 and 1211 were remoed from the market due to same reasons as freon 12 - they were grouped in the same chemical family as the freon gases.
5. There are replacement gases/systems now available - the most common are "FM-200" and "FE-241". Human exposure at correctly designed for FM-200 concentrations for short durations are not lethal nor toxic. FE-241 is for unoccupied spaces.
6. The activation method as noted in the previous post is by a sprinkler nozzle device. These are similar to the type of fire sprinkler nozzles found in buildings, etc. They have a fusible bulb or link that when the temperature is high enough (165 deg. F or more), the bulb or link will melt and the extinguishing gas will be released from the bottle.
7. The next key in extinguishing a fire (in an engine compartment) is to stop the fuel. On marine systems, an automatic fuel shutoff valve is required for diesel engines.

Ok, enough with the info - if you have halon 1301 (or 1211) system you can get it checked by a licensed fire extinguisher company but it can't be refilled if the system is activated. Either replacement systems will work as mentioned above (FM-200 or FE-136) and are avaiable at most marine supply stores. One word of caution if you plan on moving to Europe, the FM-200 is not (or will not) be available. I'm not sure about FE-136.

Kevin

 

[tilwinter]

I KNEW there was more information out there.

Captain Ron: What sort of a fire detection system are you referring to?