Auto fire extinguisher size

Hi

I need to buy an automatic fire extinguishing system.

They are sold by cabin volume.

Do I calculate the size of the engine room or by the free volume excluding the displacement of the engine?

My engine room is approx 500 cubic feet but the engines and associated mechanics probably take 200 cubic feet of that.

I’m thinking that the net free volume is 300 cubic feet, so I should over spec to 500 cubic feet. If that’s wrong then maybe I should overspec to 600? The price jumps quite a bit once you get over 500.

I don’t want to scrimp on a vital piece of safety equipment but I don’t want to waste money either.

Thoughts?

Give Fireboy a call and they can help you figure out the right system for the size of your ER.

This is not a go cheap situation.

Home - Fireboy-Xintex

The advantage of modern halon and its replacements over CO2 is that they can put out fires at concentrations that won’t kill you if you are in the space when they are released. In this case more is not better. Of course that doesn’t answer your question. I think there is a new member in the group who installs fire systems for a living. Hopefully he’ll see this and respond.

Tang said:

Hi

I need to buy an automatic fire extinguishing system.

They are sold by cabin volume.

Do I calculate the size of the engine room or by the free volume excluding the displacement of the engine?

My engine room is approx 500 cubic feet but the engines and associated mechanics probably take 200 cubic feet of that.

I’m thinking that the net free volume is 300 cubic feet, so I should over spec to 500 cubic feet. If that’s wrong then maybe I should overspec to 600? The price jumps quite a bit once you get over 500.

I don’t want to scrimp on a vital piece of safety equipment but I don’t want to waste money either.

Thoughts?

Click to expand...

You are thinking correctly. No need to go up to 600.

Keep in mind that the automatic system is only effective if the engine(s) and vent fans are shut off IMMEDIATELY on fire bottle discharge. Otherwise the running engine and vent fans will just suck all the fire suppressant out of the ER. All the automatic system I've seen require an automatic shutdown system to accomplish this. It's a pain to install, but essential if you want the fire system to actually do anything.

The Fireboy-Xintex website says the gross volume of the space must be used unless the builder has attached a nameplate deducting the volume of fixed tanks. It also says, if in doubt choose the next larger size.

I would rather go over in cubic feet than go under. But it sound like 500ft would do it. But I would call FireBoy. They maybe including everything in the E.R. to a degree.

Each of the available agents has 2 important specs: the concentration where it's effective, and the concentration where it's lethal. The wider the gap between those 2, the more you could safely over-size. IIRC, Novec 1230 has a wider spread than FM-200, for example.



Unfortunately I've never seen it available for marine use, but ideally, a system would have 2 bottles. 1 that dumps immediately (and triggers the shutdowns), then unless manually stopped, another that starts deploying a few minutes later and slowly deploys over 15 - 30 minutes to maintain the agent concentration while things cool (to prevent a re-flash). Airplane fire suppression is typically done that way, for example.

“ Selecting Your System
1. Determine the volume of your engine compartment in cubic feet or cubic meters, L x W x H. Do NOT deduct for engines, fixed tanks, or other equipment.

2. Choose your model from the Model/Size Chart:

HFC-227ea Clean Agent | FK-5-1-12 Fire Protection Fluid

Example: CG20950227 = automatic discharge with optional manual discharge, 950 cubic feet coverage.

NOTE: When in doubt, always select the larger model size for adequate protection.”

CG2 Fire Extinguisher | Fireboy-Xintex

As a note to correlate my comments to what Porgy just posted, HFC-227ea = FM200, FK-5-1-12 = Novec 1230 (Fireboy likes to use the technical names rather than the trade names for the agents).

I have oversized the bottle. My engine room bulk measurement per fireboy recomendations without allowance for machinery volume is 500 cu ft. I followed fireboy's recommendation and went up to the next bottle size without concerns for 2 reasons.

1 - I don't worry about the lethal effects of being in the engine room when the bottle trips. I don't go in there when underway, I may open the door for a look if I hear something I don't like. I won't go into an engine room on fire, alone, with no protective gear carrying a portable. That's a sure invitation to die. If the fixed system does not extinguish the fire then it will be time to call for help and abandon ship.

2 - Engines are essentially large effecient air pumps that will quickly strip the extinguishing agent to below effective concentrations from the space. PO had his orignal halon fixed system trip when the exhaust hose after the riser blew out and got surrounding flamable materials hot enough to scorch. He heard a "whomp" as the bottle tripped and the engines slowed for a few beats but never stopped running. The halon replacements also will not stop the engines. I want more time to reach for the shutdowns on the mains when the bottle trips. A bottle for 700 cu ft in a 500 cu ft engine room buys me a bit of time to stop the engines and kill the main DC power. Not much mind you but maybe enough.

If you have an automatic fixed system, are concerned about lethal concentration of the extingjishing agent and want to safely be in the space then you might consider a system similar to that used when CO2 is the agent in manned spaces. A small bottle that fires and sets off a siren, not enough to be lethal but more than enough to hear the siren over the engine noise. A short time later the main bottle trips giving you time to exit the space.

Thanks to you all for your replies. Engines would shut off quickly after activation of alarm with the option to restart them as a manual override.

I’m looking into some auto closing engine vents to prevent the gas escaping and oxygen coming in. I believe some boats come with this as standard but mine apparently doesn’t.

As a twin diesel then the risk is higher from the batteries rather than the engines so I’m thinking of having a separate manual unit over the battery box, so that I can manually activate that once the main unit has been exhausted.

If 2 dedicated systems plus the 4 handhelds haven’t put the fire out then I’m going to be watching it burn from the life raft and filling out insurance forms when I get back to shore. I’m not risking my life for a hunk of grp and iron.

City: Coupeville Wa.
Vessel Name: Pelorus
Vessel Model: Californian 42 LRC
Join Date: Oct 2015
Posts: 1,786
I have oversized the bottle. My engine room bulk measurement per fireboy recomendations without allowance for machinery volume is 500 cu ft. I followed fireboy's recommendation and went up to the next bottle size without concerns for 2 reasons.

1 - I don't worry about the lethal effects of being in the engine room when the bottle trips. I don't go in there when underway, I may open the door for a look if I hear something I don't like. I won't go into an engine room on fire, alone, with no protective gear carrying a portable. That's a sure invitation to die. If the fixed system does not extinguish the fire then it will be time to call for help and abandon ship.“

You still need to be careful. I know of one incident where two men were killed when they were just working in the engine room. They bumped into something and set off a CO2 system. They were dead before they could get out. No fire involved.

HopCar said:

City: Coupeville Wa.
Vessel Name: Pelorus
Vessel Model: Californian 42 LRC
Join Date: Oct 2015
Posts: 1,786
I have oversized the bottle. My engine room bulk measurement per fireboy recomendations without allowance for machinery volume is 500 cu ft. I followed fireboy's recommendation and went up to the next bottle size without concerns for 2 reasons.

1 - I don't worry about the lethal effects of being in the engine room when the bottle trips. I don't go in there when underway, I may open the door for a look if I hear something I don't like. I won't go into an engine room on fire, alone, with no protective gear carrying a portable. That's a sure invitation to die. If the fixed system does not extinguish the fire then it will be time to call for help and abandon ship.“

You still need to be careful. I know of one incident where two men were killed when they were just working in the engine room. They bumped into something and set off a CO2 system. They were dead before they could get out. No fire involved.

Click to expand...

Yes, CO2 is deadly and accidents can be fatal. However the discussion is about halon replacement agents and the concern that they too can be deadly when the concentration is high enough leading some to not want to oversize their bottle. Along that line I suggested the use of a system designed and installed like a CO2 system if it is a concern.

Additional thoughts related to my previouis. Further reasons to consider going up one size. Most of use don't have auto closures on the ventilation. Many of the older boats this would be very difficult to implement. Almost none of use have water tight compartments. There will always be air leaks, often through the bilge from stem to stern. It is important to keep the extingushing agent high enouth long enough to ensure the fire is out. Oversizing the bottle is one way to do that.

As to the incident you mentioned it would be good to know what they bumped that set the CO2 system off. With decades of experince on boats with properly designed and installed CO2 systems I can't envision that happening. Everytihing was well protected. There was nothing to bump in the engine room that would set the system off. If it did go off the siren and delay before the big bottle(s) released would give time to evacuate the space.

As to the incident you mentioned it would be good to know what they bumped that set the CO2 system off. With decades of experince on boats with properly designed and installed CO2 systems I can't envision that happening. Everytihing was well protected. There was nothing to bump in the engine room that would set the system off. If it did go off the siren and delay before the big bottle(s) released would give time to evacuate the space.

This happened in the early seventies at the Richard Bertram Marina near where I worked. I don’t remember the details but I was impressed that they couldn’t get out quick enough. I believe that halon and it’s replacements can be deadly too if the concentration is too high. For that reason you don’t want to go way over size on the system.

This probably explains why the guys died so quickly.
“ Carbon dioxide does not only cause asphyxiation by hypoxia but also acts as a toxicant. At high concentrations, it has been showed to cause unconsciousness almost instantaneously and respiratory arrest within 1 min [6].”

Here is a link to the complete report: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5380556/

It is the volume of the engine compartment less tankage, no other deductions are to be made for engines, equipment etc.

More here https://stevedmarineconsulting.com/wp-content/uploads/2014/03/FixedFireEx125_03.pdf

As someone who spends a great deal of time in engine rooms, my personal preference is for a non-lethal agents, even though they are not required for this 'normally unoccupied space'.

CO2 is prohibited if you seek ABYC compliance.

So many automatic systems only shut down the main engine(s). I always have the system rewired to shut down the generator too. Just my preference.

I'm an instructor at the Cruising Club of America's Safety at Sea Hands on Training courses. We trained 499 people last year -- 2/3 of which were racing to Bermuda and the rest of which are voyaging to a variety of places.


We are strongly recommending FireTKO FST which is a package about the size of a bowling ball that you toss into the engine room. It is said to be effective up to 5,300 cubic feet. Costs a little over $1,000. See https://www.lrse.com/products/firetko-fst


Unlike dry chemical fire extinguishers, the aerosol is non-corrosive. It is also non-toxic.



Jim

Circumnavigator said:

I'm an instructor at the Cruising Club of America's Safety at Sea Hands on Training courses. We trained 499 people last year -- 2/3 of which were racing to Bermuda and the rest of which are voyaging to a variety of places.


We are strongly recommending FireTKO FST which is a package about the size of a bowling ball that you toss into the engine room. It is said to be effective up to 5,300 cubic feet. Costs a little over $1,000. See https://www.lrse.com/products/firetko-fst


Unlike dry chemical fire extinguishers, the aerosol is non-corrosive. It is also non-toxic.



Jim

Click to expand...

The aerosol approach is interesting. If it's what I'm thinking of, these lack USCG or UL approval, and they require a battery to work. Can't hurt, but this is not ABYC compliant for a fixed system, and not a replacement for a fixed clean agent gaseous system.

Steve DAntonio said:

The aerosol approach is interesting. If it's what I'm thinking of, these lack USCG or UL approval, and they require a battery to work. Can't hurt, but this is not ABYC compliant for a fixed system, and not a replacement for a fixed clean agent gaseous system.

Click to expand...

Entirely correct, but incomplete. They do require a battery but it has a 15 year life, which matches the shelf life of the device.


Jim

Steve DAntonio said:

The aerosol approach is interesting. If it's what I'm thinking of, these lack USCG or UL approval, and they require a battery to work. Can't hurt, but this is not ABYC compliant for a fixed system, and not a replacement for a fixed clean agent gaseous system.

Click to expand...

ABYC can not require anything. ABYC only "recommends."

To be clear, I said "ABYC compliant", I never used the word "required". It is required if your goal is ABYC compliance.

As an adjunct to a fixed system, the aerosol unit it's fine, but no more than that.

Fixed gaseous systems can also be non-toxic, and they are non-corrosive. A fixed bottle without auto-shut off for a small compartment is well under $1000 and it is fully automatic.

I too am a Safety at Sea Instructor, having lectured on systems, damage control, and firefighting at the Naval Academy event for the past 16 years. It's a worthy cause to be sure, and applicable to power as well as sail operators.

I'm curious, this technology is new with few actual, real-world use examples, with no UL or CG approval. Other than manufacturer's advertising, on what do you, or the SAS event at which you teach, base your recommendation to those attendees? A serious question.

In my feeble mind, ABYC is trying to establish itself as the 'go to' authority but all it has accomplished is confuse the issues.

OldDan1943 said:

In my feeble mind, ABYC is trying to establish itself as the 'go to' authority but all it has accomplished is confuse the issues.

Click to expand...

And your solution is.....?
If ABYC went away today what would the resulting benefit be?

Bacchus said:

And your solution is.....?
If ABYC went away today what would the resulting benefit be?

Click to expand...

My concern is that 'recommends' may become 'must'. Then we have 2 standards to follow and comply with.

OldDan1943 said:

My concern is that 'recommends' may become 'must'. Then we have 2 standards to follow and comply with.

Click to expand...

What is the 2nd "standard"?

Would you insure a boat for a person where there were no standards followed during contruction? Or a house where no building codes were recognized?
This sort of approach is taken in many many situations

Are you suggesting that boat manufacturing becomes the wild west with no standards to be checked & verified? How about if there were no standards for the auto industry... up to each mfg what they chose to eliminate or compromise to reduce costs?
True caveat emptor!

Bacchus said:

What is the 2nd "standard"?

Would you insure a boat for a person where there were no standards followed during contruction? Or a house where no building codes were recognized?
This sort of approach is taken in many many situations

Are you suggesting that boat manufacturing becomes the wild west with no standards to be checked & verified? How about if there were no standards for the auto industry... up to each mfg what they chose to eliminate or compromise to reduce costs?
True caveat emptor!

Click to expand...

I don't see ABYC as a problem for new boat manufacture....

It's when the boating industry in general wants vessels brought to those standards when upgraded (not sure if even major repairs are included). As long as meeting the spirit is acceptable I can see that, it's when surveyors or insurers expect 100% compliance that things start to go south when 90% 0r better of the safety issues are addressed but the lesser percent ranks equally.

psneeld said:

I don't see ABYC as a problem for new boat manufacture....

It's when the boating industry in general wants vessels brought to those standards when upgraded (not sure if even major repairs are included). As long as meeting the spirit is acceptable I can see that, it's when surveyors or insurers expect 100% compliance that things start to go south when 90% 0r better of the safety issues are addressed but the lesser percent ranks equally.

Click to expand...

Absolutely!

psneeld said:

I don't see ABYC as a problem for new boat manufacture....

It's when the boating industry in general wants vessels brought to those standards when upgraded (not sure if even major repairs are included). As long as meeting the spirit is acceptable I can see that, it's when surveyors or insurers expect 100% compliance that things start to go south when 90% 0r better of the safety issues are addressed but the lesser percent ranks equally.

Click to expand...

I completely understand your point but still don't see an alternative solution being proposed. What is the proposal?... ABYC only applies to new boat sales?
DIY mods by amateur owners gets no consideration?
If that's what you want you are free to ignore ABYC and self insure or only liability if req'd to satisfy marina reqmts. That way you get to chose if you even want a survey or what to worry about if you do.

OK for new boat mfg is fine but as soon as the original sale is completed it is now a used vessel.
If you were purchasing a used vessel would you want the surveyor to overlook and not inform you of non-compliance issues?
I agree it would be nice if non-compliance issues were classified as major /important / critical and others as minor / non- critical but who decides? Surveyor, seller, buyer, insurer, broker, other???
How would an owner feel / react if an insurance Co refused a claim if they inspected a boat after a loss and cited non-compliance issues as the reason?