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From: "DaveLeonard" <daveleonard@cox.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: RE: [FlyRotary] Re: Thermocouples (was: EGT sensors)
Date: Fri, 12 Nov 2004 16:08:18 -0800
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Does anyone know, can the two types be used interchangeably with a given
monitor, or are they monitor specific?

Dave Leonard


>
> Sorry, I stand (sit) corrected.
>
> Finn
>
> Bill Dube wrote:
>
> > At 10:36 AM 11/10/2004 -0500, you wrote:
> >
> >> Al Gietzen wrote:
> >>
> >>> Subject: [FlyRotary] EGT sensors
> >>>
> >>>
> >>> Time to change the EWP subject:)
> >>> At the rotary roundup Tracy mentioned that if you have two EGT
> >>> sensors, you
> >>> can tune each rotor separately. Does anybody have two EGT sensors,
> >>> how they
> >>> are mounted and where do you get them?
> >>> Bulent
> >>> -----
> >>> I have three (20B) inconel clad K-type, clamp-in.  One in
> each header a
> >>> couple inches from the port.  Got mine from Grand Rapids
> >>> Technologies, but
> >>> you may alos be able to get them from Omega.  They are built into a
> >>> hose
> >>> clamp so you drill the hole, tighten the clamp, seal up tight.
> >>>
> >>> Al
> >>
> >> Don't you mean J-type? I believe K is lower temperature.
> >
> >
> >         The opposite is true.
> >
> >          The ASTM recommends that type J be used continuously only to
> > 760 C (1400 F). Type K are rate for continuous use up to 1260 C
> (2300 F).
> >
> >         With modern metering, type K thermocouples are superior to
> > type J. The copper lead in type J is a high thermal conductor that
> > transports heat to (or away) from the tip, resulting in increased
> > error in the measurement. The copper also oxidizes easily. Copper
> > oxide has an enormous Seebeck coefficient, so the calibration goes out
> > the window if the wire or the connections corrode.
> >
> >         The main reason that type J was popular was that it has a very
> > flat Seebeck coefficient (as a function of temperature.) This makes
> > the temperature (roughly) proportional to the voltage over a pretty
> > good range. The Seebeck coefficient for type K varies quite a bit with
> > temperature. This makes it hard to build a simple analog readout, but
> > is not a problem for a modern electronic readout.
> >
> >
> >
> >>>  Homepage:  http://www.flyrotary.com/
> >>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> >>
> >
>
>
> >>  Homepage:  http://www.flyrotary.com/
> >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>