What's the difference between the usual DIY IR guns and the ones which
they are using (Asia) to check body temperature in the epidemic?

Harry Bloomfield wrote:

What's the difference between the usual DIY IR guns and the ones which
they are using (Asia) to check body temperature in the epidemic?

very little I suspect, they do vary in the angle of the measuring "cone"

We mow know that this is a pointless thing for many viruses and bacterial
infections, unless you catch it at the exact time.
Be better off getting that test system more reliable and faster than
faffing about with infra red temperature guns.
Brian

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"Andy Burns" wrote in message
...
Harry Bloomfield wrote:

What's the difference between the usual DIY IR guns and the ones which
they are using (Asia) to check body temperature in the epidemic?

very little I suspect, they do vary in the angle of the measuring "cone"

Andy Burns explained :
very little I suspect, they do vary in the angle of the measuring "cone"

My DIY gun reads around a 3 degrees low of normal body temperature,
when checking my forehead. If there really is no difference, they must
be manually applying an off set to the reading.

Harry Bloomfield wrote:

My DIY gun reads around a 3 degrees low of normal body temperature

stick some black insulating tape on your forehead?

Brian Gaff (Sofa 2) wrote

We mow know that this is a pointless thing for many viruses and bacterial
infections, unless you catch it at the exact time.

No we don’t if you quarantine those with an elevated temperature,
even if that’s just due to the common cold or the seasonal flu.

Yes that doesn’t tell you what they are infected
with, but that doesn’t matter when you quarantine
all those with elevated temperatures.

Be better off getting that test system more reliable and faster than
faffing about with infra red temperature guns.

It isnt faffing about of that’s all you have,

We are just starting to use a test that give a result
in less than an hour but at $40 a test its never going
to be practical to use on all kids showing up at school
every day or on all those showing up at the supermarket.


"Andy Burns" wrote in message
...
Harry Bloomfield wrote:

What's the difference between the usual DIY IR guns and the ones which
they are using (Asia) to check body temperature in the epidemic?

very little I suspect, they do vary in the angle of the measuring "cone"

On 17/04/2020 19:48, Harry Bloomfield wrote:
What's the difference between the usual DIY IR guns and the ones which
they are using (Asia) to check body temperature in the epidemic?

The main difference is that the ones intended for use on humans or
animals are calibrated for the emissivity of human skin which isn't all
that close to being a black body for thermal radiation.

For precise none contact work you put a black sticker on the target that
has the right emissivity for the measurement device you are using. But
for mass screening it is easier to fiddle the detector to match "skin".

--
Regards,
Martin Brown

On Sat, 18 Apr 2020 05:39:41 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:

FLUSH all of the trolling senile cretin's latest troll**** unread again

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FredXX to Rot Speed:
"You are still an idiot and an embarrassment to your country. No wonder
we shipped the likes of you out of the British Isles. Perhaps stupidity
and criminality is inherited after all?"
Message-ID:

Martin Brown explained :
For precise none contact work you put a black sticker on the target that has
the right emissivity for the measurement device you are using. But for mass
screening it is easier to fiddle the detector to match "skin".

I knew about the black tape trick, but never saw them stick tape on the
people they were checking.

On 17/04/2020 21:50, Harry Bloomfield wrote:
Martin Brown explained :
For precise none contact work you put a black sticker on the target
that has the right emissivity for the measurement device you are
using. But for mass screening it is easier to fiddle the detector to
match "skin".

I knew about the black tape trick, but never saw them stick tape on the
people they were checking.


The black tape has to be the correct type. Some black tape may actually
act as a mirror to IR and so you are measuring the temperature of what
it is reflecting rather than what it is attached to.
--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On Sat, 18 Apr 2020 07:37:34 +0100, alan_m wrote:

On 17/04/2020 21:50, Harry Bloomfield wrote:
Martin Brown explained :
For precise none contact work you put a black sticker on the target
that has the right emissivity for the measurement device you are
using. But for mass screening it is easier to fiddle the detector to
match "skin".

I knew about the black tape trick, but never saw them stick tape on the
people they were checking.


The black tape has to be the correct type. Some black tape may actually
act as a mirror to IR and so you are measuring the temperature of what
it is reflecting rather than what it is attached to.

What about people with varying degrees of black skin ?

On 18/04/2020 08:28, John wrote:
On Sat, 18 Apr 2020 07:37:34 +0100, alan_m wrote:

On 17/04/2020 21:50, Harry Bloomfield wrote:
Martin Brown explained :
For precise none contact work you put a black sticker on the target
that has the right emissivity for the measurement device you are
using. But for mass screening it is easier to fiddle the detector to
match "skin".

I knew about the black tape trick, but never saw them stick tape on the
people they were checking.


The black tape has to be the correct type. Some black tape may actually
act as a mirror to IR and so you are measuring the temperature of what
it is reflecting rather than what it is attached to.

What about people with varying degrees of black skin ?

Black in this sense means black in the 3-20um thermal IR band which is
quite unrelated to the apparent colour in the visible spectrum.

To a first approximation almost anything opaque and non-metallic is
almost black for thermal IR but when you are trying to measure a small
temperature difference precisely on a background of ~300K you have to
compensate for the fact that skin is not an ideal opaque emitter.

Notable examples where opaque things are transparent to thermal band IR
are black bin bags and thin pine cladding. Conversely window glass is
transparent in the visible (obviously) but opaque to far IR.

https://physics.stackexchange.com/qu...infrared-light

Note how his glasses are black in the IR photo.

--
Regards,
Martin Brown

John wrote:

On Sat, 18 Apr 2020 07:37:34 +0100, alan_m wrote:

On 17/04/2020 21:50, Harry Bloomfield wrote:
Martin Brown explained :
For precise none contact work you put a black sticker on the target
that has the right emissivity for the measurement device you are
using. But for mass screening it is easier to fiddle the detector to
match "skin".

I knew about the black tape trick, but never saw them stick tape on the
people they were checking.


The black tape has to be the correct type. Some black tape may actually
act as a mirror to IR and so you are measuring the temperature of what
it is reflecting rather than what it is attached to.

What about people with varying degrees of black skin ?

Doesn't help:

https://www.cl.cam.ac.uk/~jgd1000/melanin.html

--

Roger Hayter

On 17/04/2020 20:26, Brian Gaff (Sofa 2) wrote:
We mow know that this is a pointless thing for many viruses and bacterial
infections, unless you catch it at the exact time.
Be better off getting that test system more reliable and faster than
faffing about with infra red temperature guns.
Brian

I disagree, it is useful as a rapid mass screening device that requires
no skill. I don't know how effective it was at airports etc. in the Far
East, but certainly better than nothing.

Some companies are starting to put TV monitoring systems on main office
entrances, these will be backed up by trained security staff using a
proper medical "ear-thermometer" on anyone who triggers the system.

On Sat, 18 Apr 2020 08:50:53 +0100, Martin Brown wrote:

Conversely window glass is transparent in the visible (obviously) but
opaque to far IR.

It's actually reflective. Had a play with a thermal camera the other
week, have capuured still of my thermal reflection in a glazed door.

As to the OPs orginal question I would be very surprised if the IR
thermometers generally being used to check for fever are anything
other than bog standard ones.

The actual "temperature" reading the device produces isn't that
important you're looking for an elevated temperature. Having played
with my IR thermometer and measuring skin temperature from 1/2" or so
it's moderately consistent within +/- 0.2C. That, in theory, ought to
be enough to give an indication if someone has a fever of 1 C above
normal. Trouble is depending on the exposure of the skin, ie recently
covered or not there is several degrees difference in indicated
temperature.

Conclusion, it might pickup on someone with a fever but I wouldn't
like to bet on it. A 1 degree C fever makes you feel really grotty,
it might be more reliable to look at someones eyes for "fishyness"
and their general demeaner and combine that with the IR thermometer
reading.

--
Cheers
Dave.

On 17/04/2020 20:31, Andy Burns wrote:
Harry Bloomfield wrote:

My DIY gun reads around a 3 degrees low of normal body temperature

stick some black insulating tape on your forehead?



Or point it up your nose, or into the back of your throat ?

On Friday, 17 April 2020 20:39:52 UTC+1, Rod Speed wrote:
Brian Gaff (Sofa 2) wrote

We mow know that this is a pointless thing for many viruses and bacterial
infections, unless you catch it at the exact time.

No we dont if you quarantine those with an elevated temperature,
even if thats just due to the common cold or the seasonal flu.

Yes that doesnt tell you what they are infected
with, but that doesnt matter when you quarantine
all those with elevated temperatures.

Be better off getting that test system more reliable and faster than
faffing about with infra red temperature guns.

It isnt faffing about of thats all you have,

He's right. Scary.


NT

On Friday, 17 April 2020 20:49:29 UTC+1, Martin Brown wrote:
On 17/04/2020 19:48, Harry Bloomfield wrote:
What's the difference between the usual DIY IR guns and the ones which
they are using (Asia) to check body temperature in the epidemic?

The main difference is that the ones intended for use on humans or
animals are calibrated for the emissivity of human skin which isn't all
that close to being a black body for thermal radiation.

For precise none contact work you put a black sticker on the target that
has the right emissivity for the measurement device you are using. But
for mass screening it is easier to fiddle the detector to match "skin".

The Chinese don't bother with any of that. They just pick out anyone with higher temp reading than the rest.


NT

On Saturday, 18 April 2020 19:44:39 UTC+1, wrote:
On Friday, 17 April 2020 20:39:52 UTC+1, Rod Speed wrote:
Brian Gaff (Sofa 2) wrote

We mow know that this is a pointless thing for many viruses and bacterial
infections, unless you catch it at the exact time.

No we dont if you quarantine those with an elevated temperature,
even if thats just due to the common cold or the seasonal flu.

Yes that doesnt tell you what they are infected
with, but that doesnt matter when you quarantine
all those with elevated temperatures.

Be better off getting that test system more reliable and faster than
faffing about with infra red temperature guns.

It isnt faffing about of thats all you have,

He's right. Scary.

yeah it';s almost like Trump making sense ;-) , I use my old maplin one to test the bath water, soup, oil in frying pan and other things.
Easy to tell if one thing is hotter than another and supreme accuracy to a decimal point isn't required.




NT

In article ,
Martin Brown wrote:
What's the difference between the usual DIY IR guns and the ones which
they are using (Asia) to check body temperature in the epidemic?

The main difference is that the ones intended for use on humans or
animals are calibrated for the emissivity of human skin which isn't all
that close to being a black body for thermal radiation.

Do they have settings for different skin colours? Like before and after a
holiday in the sun? ;-)

--
*Santa Claus has the right idea. Visit people only once a year.

Dave Plowman London SW
To e-mail, change noise into sound.

On 18/04/2020 11:43, Andrew wrote:
On 17/04/2020 20:31, Andy Burns wrote:
Harry Bloomfield wrote:

My DIY gun reads around a 3 degrees low of normal body temperature

stick some black insulating tape on your forehead?



Or point it up your nose, or into the back of your throat ?
They may have a resolution on 0.1 deg C, but accuracy is a different
matter and on mine is stated as +/- 1 deg C

Oral , ear canal or anal temperatures are usually the best to match
"core" body temperature which is usually quoted as a normal value of 37C .

On 19/04/2020 10:27, Dave Plowman (News) wrote:
In article ,
Martin Brown wrote:
What's the difference between the usual DIY IR guns and the ones which
they are using (Asia) to check body temperature in the epidemic?

The main difference is that the ones intended for use on humans or
animals are calibrated for the emissivity of human skin which isn't all
that close to being a black body for thermal radiation.

Do they have settings for different skin colours? Like before and after a
holiday in the sun? ;-)

Brits who have turned that peeling lobster pink colour they seem to aim
for on holiday may well show up as feverish on a temperature test.

--
Regards,
Martin Brown

Robert wrote:

point it up your nose, or into the back of your throat ?
They may have a resolution on 0.1 deg C, but accuracy is a different
matter and on mine is stated as +/- 1 deg C

Oral , ear canal or anal temperatures are usually the best to match
"core" body temperature which is usually quoted as* a normal value of 37C .

My lidaldi thermometer reads 36.x in my ear or under my tongue, where x
varies from .3 to .7

My cheapo black/yellow "gun" thermometer varies between 30.1 to 33.6
when looking at my forehead, throat or ear, sorry no black tape to hand.

On Sunday, 19 April 2020 12:08:15 UTC+1, Robert wrote:
On 18/04/2020 11:43, Andrew wrote:
On 17/04/2020 20:31, Andy Burns wrote:
Harry Bloomfield wrote:

My DIY gun reads around a 3 degrees low of normal body temperature

stick some black insulating tape on your forehead?



Or point it up your nose, or into the back of your throat ?
They may have a resolution on 0.1 deg C, but accuracy is a different
matter and on mine is stated as +/- 1 deg C

....which if Chinese means +/- 100C


NT

Oral , ear canal or anal temperatures are usually the best to match
"core" body temperature which is usually quoted as a normal value of 37C .

thankfully they're not testing those

On Sunday, 19 April 2020 12:08:15 UTC+1, Robert wrote:
On 18/04/2020 11:43, Andrew wrote:
On 17/04/2020 20:31, Andy Burns wrote:
Harry Bloomfield wrote:

My DIY gun reads around a 3 degrees low of normal body temperature

stick some black insulating tape on your forehead?



Or point it up your nose, or into the back of your throat ?
They may have a resolution on 0.1 deg C, but accuracy is a different
matter and on mine is stated as +/- 1 deg C

Oral , ear canal or anal temperatures are usually the best to match
"core" body temperature which is usually quoted as a normal value of 37C .

Be amusing to see people get off planes and having to bend over to get their temperature taken ;-)

On Sunday, 19 April 2020 14:06:19 UTC+1, Martin Brown wrote:
On 19/04/2020 10:27, Dave Plowman (News) wrote:
In article ,
Martin Brown wrote:
What's the difference between the usual DIY IR guns and the ones which
they are using (Asia) to check body temperature in the epidemic?

The main difference is that the ones intended for use on humans or
animals are calibrated for the emissivity of human skin which isn't all
that close to being a black body for thermal radiation.

Do they have settings for different skin colours? Like before and after a
holiday in the sun? ;-)

Brits who have turned that peeling lobster pink colour they seem to aim
for on holiday may well show up as feverish on a temperature test.

I go like that after about 15mins in the sun, and I'm not even ginger !


--
Regards,
Martin Brown