I asked my dad what he wanted for Christmas and he said laser thermometer.

Since I never knew they existed until he mentioned it what do you recommend?

On 08/12/2010 19:25, David Wilson wrote:
I asked my dad what he wanted for Christmas and he said laser thermometer.

Since I never knew they existed until he mentioned it what do you
recommend?




He probably means infrared thermometer. They often have laser aimers.

On my list too

Andy

In article ,
"David Wilson" writes:
I asked my dad what he wanted for Christmas and he said laser thermometer.

Since I never knew they existed until he mentioned it what do you recommend?

Perhaps he means an infra-red thermometer with laser aiming?
The laser is just a gimmic, as the field of vision is usually
something like a 30 degree cone, and not the laser dot.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

"Andrew Gabriel" wrote in message
...
In article ,
"David Wilson" writes:
I asked my dad what he wanted for Christmas and he said laser
thermometer.

Since I never knew they existed until he mentioned it what do you
recommend?

Perhaps he means an infra-red thermometer with laser aiming?
The laser is just a gimmic, as the field of vision is usually
something like a 30 degree cone, and not the laser dot.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]


Hi sorry about that, yes that is what I meant, infra red thermometer, point
it at something and it tells you the temperature, I wasn't really listening
to him when he told me.

David Wilson wrote:


"Andrew Gabriel" wrote in message
...
In article ,
"David Wilson" writes:
I asked my dad what he wanted for Christmas and he said laser
thermometer.

Since I never knew they existed until he mentioned it what do you
recommend?

Perhaps he means an infra-red thermometer with laser aiming?
The laser is just a gimmic, as the field of vision is usually
something like a 30 degree cone, and not the laser dot.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]


Hi sorry about that, yes that is what I meant, infra red thermometer,
point it at something and it tells you the temperature, I wasn't really
listening to him when he told me.
I have one of these http://tinyurl.com/34yl4rf and find it useful for
'general interest' measurements round the house and finding local
hotspots in electronic circuits and wiring, balancing radiators etc etc.
It is only chap and maybe not spot on accurate but it seems to work ok.

Bob

On 08/12/2010 22:32, Tim Streater wrote:

The only oddity is that it insists the outside walls are at -15C.

Not sure whether that remark was intended to be serious or not but with
an infra-red thermometer it does matter how good a surface is as an
emitter in the infra-red. Unpainted copper pipes seem particularly good
at providing a misleadingly low reading at elevated temperatures but
not, curiously, at ambient.

A piece of scrap copper lying on the floor gives 19C. The outlet on my
insulated hot water tank gives about 25C (scarcely higher than the
insulated surface) either side of a piece of black insulation tape
wrapped round the pipe while the tape itself enjoys a temperature of
about 55C. Has anyone an explanation for this curious state of affairs?

On 09/12/2010 08:27, Roger Chapman wrote:
On 08/12/2010 22:32, Tim Streater wrote:

The only oddity is that it insists the outside walls are at -15C.

Not sure whether that remark was intended to be serious or not but with
an infra-red thermometer it does matter how good a surface is as an
emitter in the infra-red. Unpainted copper pipes seem particularly good
at providing a misleadingly low reading at elevated temperatures but
not, curiously, at ambient.

A piece of scrap copper lying on the floor gives 19C. The outlet on my
insulated hot water tank gives about 25C (scarcely higher than the
insulated surface) either side of a piece of black insulation tape
wrapped round the pipe while the tape itself enjoys a temperature of
about 55C. Has anyone an explanation for this curious state of affairs?

IIRC a reading from a matt black surface will be the most accurate - if
you Google "emissivity" all will be revealed.

Dave

On Thu, 09 Dec 2010 10:25:40 +0000, Tim Streater
wrote:

Very serious, I was hoping to be able to identify heat leakage spots by
taking the temp of the outside of the house. It seemed odd when I took
my first outdoor reading, it said -6 or so. As I went round the house it
went progressively down to -15, where it stayed as I arrived back at my
starting point. Not sure why this should be. My device has emissivity
fixed at 0.95, but I thought ordinary brick was not too far off that
anyway.


These thermometers measure the difference between the emitting surface and the
measuring surface, i.e. the active bit inside the thermometer. If the
temperature of the thermometer head itself changes during the measurement, it'll
throw the result off.

Put the thing outside for a hour, and maybe handle it with gloves, and I'd guess
it will give more reproducible results.


Thomas Prufer

On Thu, 09 Dec 2010 15:37:54 +0000, Tim Streater wrote:
In article ,
Thomas Prufer wrote:

On Thu, 09 Dec 2010 10:25:40 +0000, Tim Streater
wrote:

Very serious, I was hoping to be able to identify heat leakage spots by
taking the temp of the outside of the house. It seemed odd when I took
my first outdoor reading, it said -6 or so. As I went round the house it
went progressively down to -15, where it stayed as I arrived back at my
starting point. Not sure why this should be. My device has emissivity
fixed at 0.95, but I thought ordinary brick was not too far off that
anyway.

These thermometers measure the difference between the emitting surface and
the measuring surface, i.e. the active bit inside the thermometer. If the
temperature of the thermometer head itself changes during the measurement,
it'll throw the result off.

Errm, how that going to work? How can the designer know what the temp of
the measuring surface is going to be? Is the device not going to measure
the amount of infra-red it receives at a set number of frequencies and,
by comparing them, deduce what the temp of the emitting surface is gonna
be?

Devices like the MLX90614 contain a reference sensor in the body of the
device. They return two sets of data: the internal device temperature
and the "seen" temperature.
ref: http://tinyurl.com/2eo43bh


Put the thing outside for a hour, and maybe handle it with gloves, and I'd
guess it will give more reproducible results.

OK I'll try that.



--
http://thisreallyismyhost.99k.org/09...0451427892.php

On Thu, 09 Dec 2010 16:15:54 GMT, pete
wrote:

Devices like the MLX90614 contain a reference sensor in the body of the
device. They return two sets of data: the internal device temperature
and the "seen" temperature.

Yup. And if the temperature of the device is changing rapidly, the internal
device temp will be off mo if the reference sensor is somewhere just a bit
aside from the active surface doing the "seeing", and the active bit is heating
or cooling (be it to a change in ambient, or to a lot of IR coming in, or
whatever), the reference sensor's temp will lead (or lag) the active surface
temp. This throws the temp. calculated from internal and "seen" off.

A look through a IR camera is also instructive: a hot, flat, plated metal
surface (i.e. chromed fittings on a radiator) can show a wild range of
temperatures. The temperature of the metal itself and the temperature of some
surface reflected in the shiny bits combine and alternate to give varying
readings. Add in that the emissivity will vary between the metal and the
reflection...


Thomas Prufer