October 12, 2015

Engine exhaust hose temperature monitoring

We occasionally participate in various boating forums. [See our Some Forums We Read sidebar for links...]

Some of those topics may be relevant here, so once in a while we will repost on our blog for reference.

The following may be one of those cases.

Link to original forum post [31-Jul-2015]

Re: Raw Water flow sensor switch alarm

Originally Posted by kevins View Post
I am thinking about putting a flow sensor/switch/alarm inline between the raw water intake pump and the heat exchanger. Has anyone done this? Any luck. I believe it will help me recognize an overheat before it happens.

any thoughts?

Hi Kevin,

With wet exhaust systems there are two basic ways to monitor the presence of sufficient cooling [injected raw] water: water flow (as you describe) and external temperature of the exhaust hose.

I chose the external monitoring method for simplicity and cost effectiveness. (No sensors inside the caustic exhaust hose environment- its bad enough on the outside...)

Another reason I chose this approach is because flow of raw water at the injection point does not necessarily mean enough water is being injected to keep the exhaust tubing at desired temperature. [e.g., What if your exhaust elbow is constricted and not allowing enough water to be injected...? A not uncommon problem prompting annual inspection and cleaning of our exhaust injection elbows as part of our PM process...]

I bought 3 submersible thermistors [extreme environment waterproof and potted] from the manufacturer for about US$10/each and put one on each engine and generator wet exhausts, with one for a spare...

For details regarding this DIY approach, read the excellent article John Lewis wrote last year published in Ocean Navigator magazine.

I hope you have fun with your project.

SV Denali Rose
Sharing our choices [good and bad...] based on facts & experience...

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