From: "Tracy rwstracy@gmail.com" <flyrotary@lancaironline.net>
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Date: Sun, 25 Apr 2021 15:19:07 -0400
Message-ID: <CAA9qwZvuv8bs1PQEcbmyoz9f5b_Ea9WgxE0=DAS4zj3BMtjY_Q@mail.gmail.com>
Subject: Re: [FlyRotary] Temperature probe placement
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Did you try wrapping some insulation around the sensor & pipe to see if
'ambient cooling' is affecting the reading?


On Sun, Apr 25, 2021 at 2:14 PM Finn Lassen finn.lassen@verizon.net <
flyrotary@lancaironline.net> wrote:

> I'm stumped.
>
> With my new coolant return plumbing (got rid of sharp 90 deg fitting) I
> relocated my temp sensors.
>
> Return from left rad used to sit on (black) 45 deg fitting and return
> from right rad on a 90 deg brass fitting.
>
> Now I have the right sensor under a silicone hose contacting the 3/4"
> alum tubing out of the radiator.
>
> The left sensor contacting the 3/4" tubing going into the return (was
> planning on moving it to left rad output tubing).
>
> The right probe now reads significantly lower (60F) than a non-contact
> thermometer pointed at rad and also when pointed at silicone hose.
>
> All sensors read the same when cooled down overnight.
>
> I realize I could clamp the right probe to the silicone hose, but felt
> that the hose would act as an insulator.
>
> Probes are LM35 or equivalent ICs. I had tested them in boiling water
> and ice baths and they were accurate within 1 to 2 deg F.
>
> I feel I'm missing something. An alum tube is a good heat conductor,
> right?  Does its color matter when sensor is directly touching it (with
> heat sink compound to ensure better contact)?
>
> I'd rather not go the route of inserting 3/4" copper tuning (with well
> for sensor) into the return hoses, but perhaps the only way to get
> accurate measurements?
>
> Finn
>
>
>
>
>
> ---
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<div dir=3D"ltr">Did you try wrapping=C2=A0some insulation around the senso=
r &amp; pipe to see if &#39;ambient cooling&#39; is affecting the reading?<=
div><br></div></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=
=3D"gmail_attr">On Sun, Apr 25, 2021 at 2:14 PM Finn Lassen <a href=3D"mail=
to:finn.lassen@verizon.net">finn.lassen@verizon.net</a> &lt;<a href=3D"mail=
to:flyrotary@lancaironline.net">flyrotary@lancaironline.net</a>&gt; wrote:<=
br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8e=
x;border-left:1px solid rgb(204,204,204);padding-left:1ex">I&#39;m stumped.=
<br>
<br>
With my new coolant return plumbing (got rid of sharp 90 deg fitting) I <br=
>
relocated my temp sensors.<br>
<br>
Return from left rad used to sit on (black) 45 deg fitting and return <br>
from right rad on a 90 deg brass fitting.<br>
<br>
Now I have the right sensor under a silicone hose contacting the 3/4&quot; =
<br>
alum tubing out of the radiator.<br>
<br>
The left sensor contacting the 3/4&quot; tubing going into the return (was =
<br>
planning on moving it to left rad output tubing).<br>
<br>
The right probe now reads significantly lower (60F) than a non-contact <br>
thermometer pointed at rad and also when pointed at silicone hose.<br>
<br>
All sensors read the same when cooled down overnight.<br>
<br>
I realize I could clamp the right probe to the silicone hose, but felt <br>
that the hose would act as an insulator.<br>
<br>
Probes are LM35 or equivalent ICs. I had tested them in boiling water <br>
and ice baths and they were accurate within 1 to 2 deg F.<br>
<br>
I feel I&#39;m missing something. An alum tube is a good heat conductor, <b=
r>
right?=C2=A0 Does its color matter when sensor is directly touching it (wit=
h <br>
heat sink compound to ensure better contact)?<br>
<br>
I&#39;d rather not go the route of inserting 3/4&quot; copper tuning (with =
well <br>
for sensor) into the return hoses, but perhaps the only way to get <br>
accurate measurements?<br>
<br>
Finn<br>
<br>
<br>
<br>
<br>
<br>
---<br>
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Archive and UnSub:=C2=A0 =C2=A0<a href=3D"http://mail.lancaironline.net:81/=
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</blockquote></div>

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