From: "Finn Lassen finn.lassen@verizon.net" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Re: Temperature probe placement
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
References: <list-1441266@logan.com>
Message-ID: <ba500ad9-bbcd-1102-e4c0-e2148bf9d794@verizon.net>
Date: Sun, 25 Apr 2021 06:20:06 -0400
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Thanks Tracy.

I've now tried that. Definitely a factor. Had no idea that the tubing 
would give up that much heat to the surrounding air.

Finn

On 4/25/2021 3:19 PM, Tracy rwstracy@gmail.com wrote:
> 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 
> <mailto:finn.lassen@verizon.net> <flyrotary@lancaironline.net 
> <mailto: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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>     Homepage: http://www.flyrotary.com/
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    <div class="moz-cite-prefix">Thanks Tracy.<br>
      <br>
      I've now tried that. Definitely a factor. Had no idea that the
      tubing would give up that much heat to the surrounding air.<br>
      <br>
      Finn<br>
      <br>
      On 4/25/2021 3:19 PM, Tracy <a class="moz-txt-link-abbreviated" href="mailto:rwstracy@gmail.com">rwstracy@gmail.com</a> wrote:<br>
    </div>
    <blockquote type="cite" cite="mid:list-1441266@logan.com">
      <meta http-equiv="content-type" content="text/html; charset=utf-8">
      <div dir="ltr">Did you try wrapping some insulation around the
        sensor &amp; pipe to see if 'ambient cooling' is affecting the
        reading?
        <div><br>
        </div>
      </div>
      <br>
      <div class="gmail_quote">
        <div dir="ltr" class="gmail_attr">On Sun, Apr 25, 2021 at 2:14
          PM Finn Lassen <a href="mailto:finn.lassen@verizon.net"
            moz-do-not-send="true">finn.lassen@verizon.net</a> &lt;<a
            href="mailto:flyrotary@lancaironline.net"
            moz-do-not-send="true">flyrotary@lancaironline.net</a>&gt;
          wrote:<br>
        </div>
        <blockquote class="gmail_quote" style="margin:0px 0px 0px
          0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">I'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" <br>
          alum tubing out of the radiator.<br>
          <br>
          The left sensor contacting the 3/4" 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'm missing something. An alum tube is a good heat
          conductor, <br>
          right?  Does its color matter when sensor is directly touching
          it (with <br>
          heat sink compound to ensure better contact)?<br>
          <br>
          I'd rather not go the route of inserting 3/4" 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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