Engine temperature with infrared thermometer

[jalfrezi]

I was given a laser point infrared thermometer. A great gadget.
I have been pointing it at my d2-40 and note varied surface temperatures.
The thermostat temperature measured with it is 85c whilst the gauge says 90degrees c.
Any comments please.
Gareth of Jalfrezi


Sent from my iPad using Cruisers Sailing Forum
Gareth Thomas

[Lepke]

Each device you use for temp reading is going to have some variance. In your case one is measuring water flow and the other is measuring surface temp.
You can use it to measure temps on exhaust ports an see if your cylinders are running even. I use mine on electrical connections and breakers to predict problems and verify I am using correct wire size.

[darylat8750]

I would consider keeping a log of the temps recorded by IR for a while. Always shoot the same spots (even a few inches will make a difference in some areas). After a while you will have a good base line and any change will give you a heads up to trouble shoot. For instance on my trawler I shoot the top of the coolant expansion tank (among other places) and take a reading at least every 4 hours. I noted a decrease of over 10 degrees. Water temp gauge on panel still showed the normal temp. I looked around and discovered that the water level was about 3 inches lower than it had been and then traced down a leak in my heat exchanger.

[Kenomac]

I picked up one of those devices for this season. It's cheap insurance. On our final sailing day last season, we had to sail right up to the dock without the engine because the warning light had come on, even though the engine did not appear to be overheating at the time, I didn't want to take any chances.

Now we can double check.

[SaltyMetals]

Think that if you get the right one, or most probably a Raymarine IR thermometer, you can connect the output to one of the new A Series plotters. I do not have one but i think this is what is mentioned in the manual.
Andrew

[dick sargent]

Being old school, I installed a pyrometer in the dry exhaust manifold in addition to other engine gauges and alarms. The best feature was it enabled me to monitor the temperature rise depending on bottom or prop fouling. When the temp rose higher than the clean-bottom temp I backed off the throttle to maintain safe temp. and prevent overheating.

[Emouchet]

On my Volvo MD2030, I have been monitoring the temperature reading from both the IR thermometer while pointing right on the temp sending unit versus the temp gauge and find out the reading are pretty consistent.

I like using the IR thermometer because I can do reading in other areas of the engine and built some knowledge about what is ood versus what is overheating for instance.
A $40 well spent.

[Tugwit]

Originally Posted by dick sargent

Being old school, I installed a pyrometer in the dry exhaust manifold in addition to other engine gauges and alarms. The best feature was it enabled me to monitor the temperature rise depending on bottom or prop fouling. When the temp rose higher than the clean-bottom temp I backed off the throttle to maintain safe temp. and prevent overheating.

Hi Dick--
At the risk of being somewhat off-topic, I recently installed a pyrometer in the exhaust manifold of my Isuzu 2AB1 diesel and have been recording temperatures under various operating conditions in order to establish a baseline. I'm interested in your experience of "normal" pyrometer readings on a small marine diesel and on the conditions where you note "abnormal" readings (e.g. as you say conditions of fouling, perhaps additional engine load due to headwinds or current, different props, etc.). Perhaps you would be so kind as to reply to me off-thread, or perhaps others would be interested in this area, as well--either as a continuation of this thread, or a new thread. What do you (and others) think?

[bcboomer]

A new thread on exhaust pyrometer readings would be interesting. I've just bought one from Cruz-Pro and have no info on optimum temperatures for my Westerbeke W46.

[Pauls]

Infrared temperature measurement is very useful, it has many advantages. However, like any tool, it also has limitations. In the case of infrared temperature measurement, the tool does not actually measure temperature. It is measuring the energy emitted by the surface in the infrared band. Because the emitted energy can vary greatly depending on the type of surface - ie its color, surface roughness, etc - exact temperature measurement with infrared is not possible without calibration for the surface characteristics (called emissivity, ie the energy emission characteristics of the surface). So you can expect to see some variation between the infrared readings and other measurement devices.

Also, bear in mind that ALL measurement has error, and retail level temp measurement probably has measureable error. That is why in industry measurement tools are calibrated regularly.

All that said, you don't need high accuracy, you're just checking on your engine temps, and for that the tools you've got are most likely fine.

I design and build infrared sensing equipment, the above is accurate.

[paulajayne]

Need to set it for the material being measured.

ThermoWorks Emissivity Table

[Tikka]

1/ set for type of surface engine block recommend 0.95
2/ internal and external block temperature is very different
/surface air cooling, affects measurement/
using IR thermometer is tricky, in most cases red dot is not
indication where is temperature measured

if you measure different surface, setting different constant is important,
personally, wouldn't worry too much, cheap IR are marginal anyway.

[Cheechako]

I bought an IR thermostat for my Grandson for Xmas. Very handy device. Aim and shoot.. what could be easier? They are used for all kinds of things including industrial checking of high voltage wire runs on the inside ceiling of buildings for heat/hot spots. Would have been very handy when I was living aboard.

[StuM]

Originally Posted by paulajayne

Need to set it for the material being measured.

ThermoWorks Emissivity Table

Cheaper ones don't have emissivity adjustment. They are fixed at around 0.95.

If you want a bit more accuracy/consistency on various parts of the engine, stick patches of duct tape on your targets .

[Tkeeth]

Originally Posted by StuM

Cheaper ones don't have emissivity adjustment. They are fixed at around 0.95.

If you want a bit more accuracy/consistency on various parts of the engine, stick patches of duct tape on your targets .

Flat black electrical tape works better, it has an emissivity at about .95. Also be aware, the laser pointer is a marker and has nothing to do with measurment. In the side of your device will be a cone that will give the size of the measurement spot at a certain distance. You generaly want to be closer. Paul is correct. I am a IR professional 20+ years