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infrared thermometer transparent material hanoverrov 2/25/2010
Hello I am a student at Hanover High School and are attending a mate rov competition soon and I was wondering if there are any transparent materials that I could use to measure temperature underwater with the infrared thermometer?
 
Re:infrared thermometer transparent material Raphael ITC Eurasia 2/25/2010
hanoverrov wrote:
am a student at Hanover High School and are attending a mate rov competition soon and I was wondering if there are any transparent materials that I could use to measure temperature underwater with the infrared thermometer?
Unfortunately, water is opaque for infrared equipment. You cannot do any underwater measurement with such a device.
 
Re:infrared thermometer transparent material hanoverrov 2/26/2010
Raphael ITC Eurasia wrote:
Unfortunately, water is opaque for infrared equipment. You cannot do any underwater measurement with such a device.
all we are trying to do is find the difference of the temperature from the water, not the actual temperature. is this possible?


 
Re:infrared thermometer transparent material JKEngineer 2/27/2010
If the object you want to measure is under water, then you cannot use IR to measure its temperature. The water will absorb all the IR radiation that the object emits, so that the IR sensor will not see it. Think of trying to see something in the bottom of a bowl of pea soup.

What you could consider, depending on what the object is, is to use thermocouples or similar contact temperature sensors.

If the object can be taken out of the water and IMMEDIATELY looked at, you have a chance to measure it with IR. This has been done by others, however I have always questioned the validity of it, since there is still water on the object so that you are measuring the temperature of the thin layer of water, not the object. If there is a temperature profile for the water vs. depth then you are also not sure which water is left on the object as you remove it from the water. This means you are introducing errors, from several sources.

Another alternative, also not great, would be to use a "glass bottom bucket" approach as is done to look below the surface of water by eye. In your case the bottom of the bucket would have to be an IR transparent material, such as thin film food wrap or garbage bags (even the black ones). You would make the plastic in the bottom large enough to be slack, push the bucket down onto the object until the plastic conformed to it, and quickly take the temperature. You would still have a film of water on the object and would be measuring that. Also the temperature of the object would start changing as soon as you contacted it with the plastic.

Since I have no clue as to what a mate rov competition is, I can't give you more specific advice.

Jack
Jack M. Kleinfeld, P.E.
Kleinfeld Technical Services, Inc.
Infrared Thermography, Finite Element Analysis, Process Engineering

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