Halon Volume For Engine Room

[Terry Etapa]

I've got a 13 lb halon 1211 fire extinguisher mounted on a bulkhead outside of my engine room. It's meant to be discharged through a port into the engine room.

I have been trying to determine if it has enough capability to be used in the volume of my engine room. I haven't had any luck.

Is it as simple as pounds of halon per cubic foot of volume? If so, does anyone know what the number is?

[ 12-06-2004, 06:50 PM: Message edited by: Terry Etapa ]

[capt jake]

Terry, I don't have your requested data at hand, but I have a couple of concerns with Halon.

1 - Recent EPA regulations have made Halon very expensive to service and maintain.

2 - Halon work by O2 exclusion and interupting the chemical reaction to extinguish a fire. It is quite effective on electrical fires and it has the benefit of not damaging electronics (like dry chem will).

This being said, I would have to wonder about it's effectiveness on an engine room fire as this would typically be a class B fire (flam liquids) where an agent with cooling effects would have the greatest benefits.

Just a couple thoughts.

[mmd]

Transport Canada is phasing out useage of halon as a fire supressant. From the Transport Canada website:


"Halon, as a fire suppressant, is being phased out in Canada. Refills of portable equipment will be banned after 2003. A fixed fire extinguishing system will be permitted one refill between 2005 and 2010 provided the system is replaced one year after that."

[capt jake]

What mmd says also applies here, though I am not sure of the final date the US has set. It's components damage the ozone, thus it is being eliminated.

There have been some recent breakthroughs in regards to extinguishers. Check out the class K extinguishers. Though they were primarily design for grease fires in kitchens, they do have a class B rating. They have proved to be very effective and got the approval by UL to retro-actively replace all pre-existing systems in kitchens (the on retro-active requirement ever).

This new extinguishing agent (wet chemical) was developed with the assistance of McDonalds believe it or not. It makes much less mess than dry chemical and cleans up very easily.

I guess I should also add; I do not know about the CG regulations in this area. It sometimes takes a while for all of the key players to start reading from the same sheet of music. I am very familiar with installations in structures that don't float. ;) There has been great strides to unify the standards and codes in recent years. Hopefully there will be some consistancy in the near future.

[ 12-07-2004, 11:14 AM: Message edited by: capt jake ]

[Terry Etapa]

I just paid $130 USD to get my 13 lb halon bottle serviced. That included a hydro, which is good for 6 years. The replacement cost would be over $600 USD. Replacements are more economical?

My only modification to the system is adding a USCG approved bracket. It was held in place by a hook, like seen in buildings.

My question is still the same, was this bottle properly sized for my engine room?

[capt jake]

Ask the people who serviced it.

[Bob Smalser]

I remember the M1 tank having a total of 25lbs of halon....but that system was designed for a hotter fire.

Take a look here and see if you can find what you need:


The US Army currently has
three fielded ground vehicles using Halon 1301 to protect their crew compartments: the M1 Abrams main battle tank, the
M2/M3 Bradley Fighting Vehicle, and the M992 Field Artillery Ammunition Support Vehicle (FAASV). The crew
compartments of these vehicles range in volume from 250 to 700 ft3 and employ from seven pounds of halon 1301 in a
single shot to 21 pounds in each of two shots. http://www.dtic.mil/ndia/11ground/clauson.pdf#search='pounds%20pressurized%20halon%2 0m1%20abrams%20tank'

[mmd]

A 13-lb Halon cylinder will supposedly protect an engine room volume of 240 cu. ft. (measure your engine space L x B x D, then subtract the volume of any sealed tanks such as fuel, water, oil, etc. Do not subtract the volume of the engine(s)). This assumes that the engine room can be completely sealed off from external spaces (most yachts - especially wooden ones - can't) and that the engine(s) are at a complete stop when the halon is applied. If there is any way air can get in or halon can get out of the engine space, more halon is needed. If the engine(s) are still running when the halon is discharged, they will suck in halon and exhaust it out before stalling for lack of oxygen. Some sources suggest up to 1.5x the reccommend halon supply for a given space.

As far as I know, the USA is the only nation in the western world (and most others) that has not yet banned halon. You may wish to check to see if it is legal for you to sail in Canadian waters with a halon system aboard - an inspection by the Canadian Coast Guard may result in your removing the installed cylinder(s) and disposing of it/them properly, at your expense.

For more information on halon replacements, see here (http://www.kortjacht.nl/blussers/SEA-FIRE%20LEAFLET.pdf) or here (http://www.epa.gov/ozone/snap/fire/qa.html) or here (http://www.unitor.com/internet/info/features/docs/20001113.htm) .

USCG guuidelines for CO2 and halon fire supression systems are here (http://www.uscg.mil/hq/msc/PRGuidance/E1-06%20.pdf) .

[JimConlin]

I recollect that the principal argument for halon over CO2 systems was that it was less nasty to the people in the space being gassed, and that if there weren't people in the space, CO2 was fine, and less of an environmental problem. Can your 13 lbs of halon be profitably recycled and can you easily switch to a CO2 extinguisher?

[Paul H]

Halon 1211 was designed as a streaming clean agent, ie for use in extinguishers. It was used for some total flooding systems many years back.

Halon 1301 was designed for total flooding applications, and at a 7% by volume application rate. 1211 application rates are different, and I don't know off the top of my head, as I've never come across one nor calced one.

My texts are at home, but you should be able to find something on google to do some rough calculations.

Halon is very effective on hydrocarbon fires. When I've used and seen it used during extingquisher training on a diesel pan fire, it looked like it magically extinguished the fire. Dry chem works well, when you get it down to the fuel. CO2 would blow the flames away, but as soon as you moved the stream, it would flame up again.

A caveat with halocarbon fire fighting agents (Halons) is that while they produce no health effects by themselves in proper percentages, when they break down in the process of fighting a fire, the components they break down to are quite nasty, ie bromic and fluoric acid.

Halon prices are curious, for awhile they were very high, but then a sufficient number of systems have been taken out of service, and the holon recycled, so that the price has dropped.

The wet chemical systems were designed for use on hot oil fryers. The reason they have replaced previous systems is the change from lard based to oil based friers. The previous systems would cause the lard to saponify, and hence make a soap type layer that would prevent oxygen from getting to the lard. The vegitable oils used in fries today don't react in the same way, hence the switch to wet chem.

I don't know of any uses of wet chem systems in the oil and gas industry. The standard for pool based liquid hydrocarbon fire fighting is AFFF foam. Dry chemical, water mist and some of the newer clean agent systems are also being employed in certain applications.

There is no perfect fire fighting medium for all fires, each has it's strengths and weaknesses.

There was (is?) a product called fire trace, as I recall, that would allow you to install a fairly inexspensive automatic total flooding system using either CO2 or dry chem. It is a plastic tubing that you run through your engine room, is pressurized with your extinquishing agent, and melts to allow the extinquishent to discharge on the source or sources of heat.

A previous employer of mine was going to be the Alaska rep, but we just never had any applications for the product. I know it was being used in engine compartments of large dump trucks used in the mining industry.

[Paul H]

Since I get to do calculations so infrequently, and I'm sick and tired of doing estimates, procedures, and job progressing, I did a little research on 1211.

Assuming I didn't screw up the calculation, which is a possibility, you should be able to obtain a 7% concentration of 1211 at 75 deg F in an approximate volume of 400 cu foot. I actually reduced the agent to 12#'s, as 1211 requires approximately 10% more agent then 1301, and then I rounded down the volume a touch. If you have openings in the enclosure, especially at the bottom of the enclosure, you will get halon leakage and hence lower the concentration.

[Terry Etapa]

Thanks for all the help. My engine room is roughly about 230 cubic feet. It looks like my "system" is acceptable per what mmd and Paul have said. I can now worry about the real work of converting a fishboat, and forget about fire suppression for now. Well, make that think less about fire suppression for now.

I also have two 3 lb halon, and two 3 lb dry chemical extinguishers onboard. In 6 years, when the 13 lb halon bottle needs a hydro, I'll look into one of the pre-engineered systems. My halon can then be a backup.

[Peter Malcolm Jardine]

I don't have an engine room system. I use a sniffer, and have 4 ABC extinguishers on board...3 eights and a five. On gasoline installations, the biggest danger is right after fueling. I personally inspected (and installed) my gas lines, which are all copper of course, and I inspect every spring. I also installed another high capacity blower, so there are two with dual inlets on each.

[Paul H]

Terry,

I checked out your website, a great project indeed. If I had the facilities, I'd probably tackle something similar. As it is, the Tolman skiff I'm building provides the least boat I can live with, and still fit in my garage.

I converted trawler would definately be the ticket.

I dug up fire traces website, and am going to get some literature. The 240 cu ft coverage for the 13# bottle must be for a higher concentration then I calced.