ER Fire Control

[David Rive]

I would like to add an automatic extinguisher to Waterthrush's engine room. In browsing the Xintrex-Fireboy website, they say an automatic engine shutdown system is "required" in installations involving diesel engines. I understand the logic - you don't want your engines continuing to suck in and circulate air while you are trying to kill a fire. On the other hand, when my engines are running, I am always within 1 or 2 seconds reach of the engine kill switches at the helm ... if the alarm went off and the extinguisher discharged I could kill the engines almost as fast as an automatic system would.

So my question is - are these automatic engine shutdown gizmos really required?

 

[koliver]

Your engines will ingest an ER fire if the fire occurs within a few feet of the intake. If the automatic extinguisher is outside of that range, it may not sense the fire until the engine has already consumed the air cleaner and other combustibles at that part of the ER. If it is located close by and douses the fire, it will also douse the intake and your engine will have sucked in a lot of very damaging extinguisher contents, likely taking so much away from dousing the fire that the fire still burns.
So yes, a shutdown system linked to the automatic fire suppression system is a good idea.

 

[ulysses]

Absolutely agree with Keith. The sizing of the extinguishing agent is based upon the volume of the engine room space w/out the numerous cubic feet of air the engine is drawing into the engine room every second it is running. Likewise the ventilation system, if equipped, should be shut off. Furthermore don't be in the engine room space when the system deploys there should be an alarm equipped with the system that allow a few seconds to escape before it deploys the agent. Remember that most agents Halon, C02, etc. are heavier than air so the old practice of getting low in a fire does not apply once it goes off.

 

[Capt.Bill11]

Actually one of the main problems with not having an automatic engine/gen shut down is the fact that the engine/gen could suck all the extinguishing agent out before it has a chance to kill the fire.

 

[Chrisjs]

Our automatic shut down switch was always set to automatic but did have a manual override in the event that safety/navigation needs outweighed extinguishing the fire. Tough call to make unless a large ship is headed directly for you!! The switch itself should not be so costly in relation to (professionally) installing the Fireboy. So perhaps the OP's issue is difficulty of running the switch wiring to the helm. Perhaps an option is to locate the automatic switch where wiring is not such a problem, and trust that the really big ship does not show up if and when there is an engine room fire. Not sure if this would satisfy an insurance company. We needed to have our Fireboy professionally inspected annually along with other fire extinguishers for insurance.

 

[David Rive]

Thanks for the feedback everybody. Clearly I need the automatic shutdown system.

 

[willpep]

I had a Fireboy installed on my Mainship 30. During one cruise, the black box which is supposed to, in the event of a fire, shut down blowers and kill the engine decided just to kill the engine (no fire). After some investigation (mostly on boatdiesel.com) I decided to throw the black box overboard. The halon fire extinguisher is still installed. Now the Captain decides when to shut down the engine.

Cheers

 

[FF]

One problem is there must be delay between killing the engine (s) so the RPM can go to zero to keep the engine from pumping the extinguishing agent thru its exhaust.

 

[willpep]

Agree. It could create a runaway engine situation. On my list is to change the extinguisher from automatic to manual. I haven't done any research here yet.

However, I pretty much stand on top of my engine box and am relying on my senses to hit the kill switch.

I just had a bad experience and decided the risk of loosing power for a computer glitch wasn't worth it. Just my 2c.

Cheers

 

[Fletcher500]

I went Through the same thought process as you when I was. researching this.

Theoretically, and practically speaking the engine shutdown is the correct answer.

One of my biggest concerns is losing the engines. I was also concerned that these interlocks could potentially shut them down through a false trip. I Therefore installed the automatic fire boy clean agent system,but did not do an interlock to shut the engines down.

I used a larger container volume of agent to provide a safety factor which I am counting on to certain extent.

I am not implying that my approach is the right way but it works for me.

 

[ulysses]

I am not sure what "safety factor" you were using but it should involve the Max. Air Flow through your engine (s) per minute. It would not be uncommon for one turbo-charged engine to flow over 600 cubic feet or air per minute which is probably close to half the air volume of an average engine room and therefore probably half of the extinguishing agent. Halon or C02 is going to kill the engine (s) pretty quickly anyway, I am pretty sure the newer agents will also. What would make for a bad day is for the engines to be running and use up most of the extinguishing agent then shut down. Then you would still have a fire and no engines.

 

[Fletcher500]

As noted, I am in basic agreement with the logic here, so I was reluctant to even post.

My concern is those interlocks shutting down my engines as I am driving by a jetty,, At the offshore islands and landing on the rocks, or even down the fairway and playing ping-pong off other boats in their slips. Those interlocks can and have failed.

I didn't want want to take that risk. If you go to other sites you will see that it is a valid concern.

 

[psneeld]

I too am not fond of auto shutdown for the main propulsion.

Maybe silly but after all those hours of flying without auto shutdown and equally devastating possible outcomes....I'll stick with my investigate, formulate concept rather than auto shutdown.

But I realize that may not be for everyone. Just size and complexity of boat and crew could swing my decision.

 

[ulysses]

I certainly see the problem with a false shut-down. The other thing that E.R. fires or for that matter any boat fire creates is usually if not the cause of a fire certainly one of the earliest effects is you will lose most all electricity. Melting and groundings of wires. If it is located away from the heat sensors you may have problems doing anything. You would think someone would come up with some improvements on the systems or at least a sequence with alarms and over-ride ability.

 

[psneeld]

Based on the dozens of small vessel fires I have been involved with......

I am convinced a simple smoke detection system if it can be in clean enough engine room air to avoid false alarms....it would be the best early warning system.

Most fires start as electrical and most are smoldering probably for awhile....thus the smoke detector.

With a simple early alarm...your options now have expanded.

Waiting for an engine compartment bottle to shut you down and hopefully extinguish the fire has now has compounded things. That is because most boat fires are electrical and unless it or you shut down electrical circuits, a reflash is possible .....AND now you could possibly be getting the snot beat out of you because you are DIW.

The auto shutdown feature and engine room bottles on smaller vessels sound good on paper...just not from my experience.

Iit seems the insurance companies don't think they are that great as they say there is no discount for having an installed system on my last 2 boats.

 

[ksanders]

I was worried about the risk of an automatic shutdown system as well. Having my engines shut down at the wrong time kept me awake at night.


I decided to not use an automatic shutdown for the very reasons listed in this thread.

First off someone is always at the helm when the mains are running. When the generator is running someone is no more than 10 seconds away.

The helm indicator of a discharge is bright and it it LOUD. For me, The risk of an inadvertant engine shutdown is not worth the added few seconds.

FYI I also have a smoke detector in the engine bay. It is a standard home unit, linked to my Lowes Iris alarm system. For all the naysayerrs advocating a "marine" only system, that is complete and unadluterated Bull XXXX. I have had ZERO false alarms in a pretty much full season of use. Probably a hundred fifty or 200 hours on the engines .

 

[Simi 60]

One problem is there must be delay between killing the engine (s) so the RPM can go to zero to keep the engine from pumping the extinguishing agent thru its exhaust.

The delay could be the time it takes to run from the helm station kill switch to the engine room or nearby extinguisher button.
Down 2 levels for me, maybe the button one level down in the living space.

 

[Simi 60]

my Lowes Iris alarm system.

This?

Iris by Lowe's Second Generation review - CNET

 

[Jeffrey S]

If an engine ingests the fire retardant, won't that displace oxygen in the engine and won't the engine slow down on its own (if not stall)? Just put a block of wood against the oxygen intake of aCappella's engines, and it comes to a pretty controlled stop.

 

[ulysses]

Jeffrey S : I believe the concern is the automatic engine shut down falsely shutting the engine down when there is not an actual fire. I believe you are correct that in the case of a fire and the extinguishing agent being deployed the engine is going to shut down. I have used a C02 hand held extinguisher to shut down a run a way engine in the past. The question then arises as to if the engine is running how much agent is lost to the engine and how much is required to extinguish any fire that may be present.

 

[ksanders]

This?

Iris by Lowe's Second Generation review - CNET

Yes, although i have not read the review.

I have

4 smoke and CO detectors
2 high bilge water detectors
1 energy monitor
1 contact sensor hacked to read my SOC meter for alarm conditions
3 motion sensors
3 more contact sensors.

I even monitor the temperature of the fridge using a contact sensor.