Aquaalarm exhaust temperature alarm

[larman]

I would like to install an aqualarm exhaust temperature alarm on my cummins 6bta has anyone had any experience with the installation or the product?

[bshanafelt]

my motor is a 6bt and the install is simple. I put the sensor on a fiberglass 90 fitting about 10" from the exhaust riser/spray head.

Nice cheap insurance for a heads up on overheat or loss of raw water

good luck

[Choices]

They made me a custom one with one display for main engine and gen set. Pretty simple.

[Comodave]

I have put Borel alarms in several boats now. Very easy install. You can also have a high water alarm and WIF alarm.

[larman]

Originally Posted by bshanafelt

my motor is a 6bt and the install is simple. I put the sensor on a fiberglass 90 fitting about 10" from the exhaust riser/spray head.

Nice cheap insurance for a heads up on overheat or loss of raw water

good luck

Thanks for the reply. Would happen to have a picture of the install location.

[Captain Doug]

Seaboard Marine make a combo boost/pyrometer kit that was very easy to install and allows you instant feedback on EGT and boost.

[C lectric]

Originally Posted by bshanafelt

my motor is a 6bt and the install is simple. I put the sensor on a fiberglass 90 fitting about 10" from the exhaust riser/spray head.

Nice cheap insurance for a heads up on overheat or loss of raw water

good luck

My understanding is the sensor should go on the metal parts just after the shower head. THe installation on a fiberlgass part or a hose will seriously slow the reaction of a too hot exhaust from lack of water flow.

[Captain Doug]

For EGT location see Tony’s Tips on s mar website under exhaust systems, it has a photo.

[Captain Doug]

Starboard Marine photo of pyrometer install location on 6bta 5.9 M3.

[Jeff F]

I *think* that there are two different needs being discussed here.

EGT measures temps before the water is introduced into the exhaust. The exhaust temperature alarm is meant to measure farther downstream and goes off if for some reason the water flow is interrupted or constrained, and is pretty much independent of EGT.

Maybe I'm wrong, but I think the OP is talking about the latter.

[Comodave]

Originally Posted by Jeff F

I *think* that there are two different needs being discussed here.

EGT measures temps before the water is introduced into the exhaust. The exhaust temperature alarm is meant to measure farther downstream and goes off if for some reason the water flow is interrupted or constrained, and is pretty much independent of EGT.

Maybe I'm wrong, but I think the OP is talking about the latter.

That was my understanding too.

[C lectric]

bshanafelt's
description of his mounting location told me he was installing a loss of raw water temperature sensor. Often nothing more than a temp. sensitive switch such as an Airpax sw. which can be had in many ratings. THe catch is it should be mounted on the metal parts just after the raw water injection point into the exhaust stream. Not on either a fiberglass part or a hose as they are insulators and may materially delay the sw. reaction.

These alarms are usually set for activation, switch contacts close, of about 160oF to 170o F to give enough time to realize what the alarm is about and prevent damage to the fiberglass and hose components beyond.

I use some of these switches, Airpax, but for different although similar situations.


EGT is a different use. It measures the actual exhaust gas temp. as that gas exits the cylinders. That gas exiting can be as little at idle as less than 200oF to 300oF. When the engine is actually under load that temp. can rise dramatically to easily 500oF [easy operation] up to 1,000o F. [full plane run hard]

The two uses have nothing to do with each other. other than temps. One is a monitoring system of the exhaust gas temperature , one is an alarm that the temp is to high and of raw water loss.

If there are question about what I have suggested go to
www.sbmar.co and read TOny Athens descriptions of the two uses.

[bshanafelt]

Hello C lectric

As it happens, I have both EGT pyrometer and the downstream raw water alarm.
Very different probes doing very different things as stated.

To the mounting of the raw water failure temperature alarm, I would be happy to mount it on a metal part downstream of the shower, but there is none in my wet exhaust system.
It consists of exhaust hose or fiberglass tubing/fittings and a fiberglass silencer.
So, it is mounted on the first fitting downstream of the shower, which is fiberglass.

I suppose the fiberglass fitting would eventually melt if raw water failed, hopefully it would alarm prior to a melt thru.


FWIW, the exhaust system performed flawlessly for 2500 hrs before this alarm was installed and 1000 hrs since.

[Bmarler]

Mounting just downstream of the elbow is common and an acceptable position for the sensor. The hose or tube will heat very quickly in absence of cooling water.

[socalrider]

Originally Posted by Bmarler

Mounting just downstream of the elbow is common and an acceptable position for the sensor. The hose or tube will heat very quickly in absence of cooling water.

Yup - you can test the sensor with a heat gun. I added them as well; much quicker to respond to an impeller failure/blockage than engine coolant temp - potential boat saver.

[CompuNerd]

...except when the cooling water sensor fails.


Had that happen this fall. No audible alarm until the EGT went off, and by that time had to baby the engine at dead slow speed back to the marina. Destroyed the impeller but didn't fry the engine. I've now installed a raw water flow alarm between the raw water strainer and the impeller pump, so I have three alarms for the cooiing system: raw water flow, EGT, and cooling water temp.


As always, YMMV.

[socalrider]

Originally Posted by CompuNerd

...except when the cooling water sensor fails.


Had that happen this fall. No audible alarm until the EGT went off, and by that time had to baby the engine at dead slow speed back to the marina. Destroyed the impeller but didn't fry the engine. I've now installed a raw water flow alarm between the raw water strainer and the impeller pump, so I have three alarms for the cooiing system: raw water flow, EGT, and cooling water temp.


As always, YMMV.

That sounds frightening! What caused the sensor failure?

I'm surprised your EGT read high due to a cooling failure - would suspect that engine coolant temp would be the next thing to notify of a problem. I think of EGT as a tool for calibrating prop pitch (if you have a variable pitch prop) or monitoring your turbos, not something that would be useful in identifying a cooling problem. But there's a lot I don't know about boats!

[Jeff F]

Yeah, EGT would be the last to spike.

[heysteve]

I recently installed the Borel wet exhaust temperature sensor. Just to be clear, this mounts on the rubber hose just after the raw water injection point. Exact instructions are available here.

[firehoser75]

Originally Posted by heysteve

I recently installed the Borel wet exhaust temperature sensor. Just to be clear, this mounts on the rubber hose just after the raw water injection point. Exact instructions are available here.

This the correct location and method for installing this alarm. I installed one on my 6BTA engine, and it potentially saved me from suffering expensive damage due to a pending overheat condition or maybe also a failure of the exhaust hose potentially allowing hot exhaust gases and hot salt water into my ER!! I picked the Borel brand (very similar) as it alarms at a lower temp than the Aqualarm model, but still has enough of a temp differential to avoid "false alarms".
I also installed an Aqualarm water flow alarm between the strainer and the raw water pump. The flow alarm will help "save an impeller" should you forget to open the thru hull, or should you "suck in" some kind of blockage.
The exhaust hose alarm will notify you of an impending overheat from basically any cause (to do with the raw water side). The first place to show signs of an impending overheat is this location, and theses alarms (Borel or Aqualarm) will give warning (assuming no malfunction) before your engine suffers damage. It will alarm before the engine (coolant) reaches high enough temps to alarm the regular "overheat" alarm. The exhaust alarm may not sound soon enough to "save" an impeller from damage and the extra work that would entail fishing out the pieces and installing a new one, hence the water flow alarm in addition.

I wired them both to an Aqualarm "panel" located near the helm. Believe me, the alarm sound cannot be overlooked. It is loud.
These alarms are relatively easy to install, and are inexpensive as far as boat "things" go. I highly recommend these 2 types of alarms to help avoid a potential engine destroying (at least severe damage) severe overheat.
I am not affiliated in any way with these companies, just a customer.