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nuckolls.bob(at)aeroelect
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 Posted: Mon Oct 31, 2016 9:43 am Post subject: CHT challenge . . . |
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At 01:45 AM 10/31/2016, you wrote:
Hi Bob,
I found your discussion on building your own sensors
in AeroElectric Connection very informative, however,
it raises a question: Can any CHT sensor be used with
any CHT gauge as long as the temp ranges are the same
for both devices?
Theoretically possible but as a practical
matter, maybe not. A thermocouple is a
voltage versus temperature SOURCE. As long
as the instrument reading the voltage draws
ZERO current from the source, then that gage
may be sued with any thermocouple of the
right voltage/temperature curve. Most CHT
couples are type K . . . but there ARE a few
type J devices out there to.
As a practical matter, you can parallel any
number of electronic instrumentation systems
onto a single thermocouple . . . electronic
gages have a very high input impedance and do
no 'pollute' the thermocouple's data.
But ALL un-powered temperature displays
place some demand on the thermocouple
making it necessary to MATCH a gage with
a thermocouple based on wire type (J,K,E,T)
and resistance of the thermocouple lead-wire.
I have installed a C90-12F on my Zenith CH750 project and want to hook up at least one CHT sensor until I can confirm nominal temps within the experimental cowl that is provided. And I don’t want to spend hundreds of bucks if not necessary.
A local acft used parts shop has a couple of used CHT gauges available at very reasonable prices but without sensors and wiring.
Acft Spruce provides a sensor CP131 CHT Probe 18m, part number 10-01440. This sensor will fit under one of my selected cylinder spark plugs.
Would such a sensor work properly with a used CHT gauge? The used gauge I have in mind reads to 600 F and has two leads which I assume connect to the appropriate two leads from the sensor.
The Aircraft Spruce catalog speaks to the use of type E
thermocouple wire on their spark plug gasket offering.
Here are excerpts from the data tables on the three popular
thermocouple types.
Type E
[img]cid:7.1.0.9.0.20161031124007.0216e880(at)aeroelectric.com.0[/img]
Tyoe J
[img]cid:7.1.0.9.0.20161031124007.0216e880(at)aeroelectric.com.1[/img]
Type K
[img]cid:7.1.0.9.0.20161031124007.0216e880(at)aeroelectric.com.2[/img]
As you can see, type E has a lot more output
that J and K. The tough nut is that any gage
used with this particular produce must be
MATCHED to the wire.
The answer to your question is bounded by two
points: (1) match gage to type of thermocouple
wire and (2) finding an 18mm spark-plug gasket
fitted wire appropriate to the gage.
Bob . . .
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rampil
Joined: 04 May 2007
Posts: 870
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| Posted: Mon Oct 31, 2016 12:23 pm Post subject: Re: CHT challenge . . . |
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So far as I know, a cht gauge must match
the alloy combo (i.e., the letter type) of the
TC. Printed temp scale is not relevant. Different
alloy combos output different voltages at the
same temp point.
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_________________
Ira N224XS |
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billbear
Joined: 26 Oct 2012
Posts: 7
Location: Alasska
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| Posted: Tue Nov 01, 2016 3:45 pm Post subject: CHT challenge . . . |
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Thanks, Ira,
I got the same info from Bob N. in an email. Presently waiting on a reply from the gauge manufacture for data on the alloy combo for a Falcon gauge.
Bill
On Oct 31, 2016, at 12:23, rampil <ira.rampil(at)gmail.com> wrote:
| Quote: |
So far as I know, a cht gauge must match
the alloy combo (i.e., the letter type) of the
TC. Printed temp scale is not relevant. Different
alloy combos output different voltages at the
same temp point.
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=461777#461777
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billbear
Joined: 26 Oct 2012
Posts: 7
Location: Alasska
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| Posted: Fri Nov 04, 2016 5:37 pm Post subject: CHT challenge . . . |
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Thanks, Bob,Your discussion cleared up my concern - very helpful.
Bill
On Oct 31, 2016, at 9:42, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 01:45 AM 10/31/2016, you wrote:
Hi Bob,
I found your discussion on building your own sensors
in AeroElectric Connection very informative, however,
it raises a question: Can any CHT sensor be used with
any CHT gauge as long as the temp ranges are the same
for both devices?
Theoretically possible but as a practical
matter, maybe not. A thermocouple is a
voltage versus temperature SOURCE. As long
as the instrument reading the voltage draws
ZERO current from the source, then that gage
may be sued with any thermocouple of the
right voltage/temperature curve. Most CHT
couples are type K . . . but there ARE a few
type J devices out there to.
As a practical matter, you can parallel any
number of electronic instrumentation systems
onto a single thermocouple . . . electronic
gages have a very high input impedance and do
no 'pollute' the thermocouple's data.
But ALL un-powered temperature displays
place some demand on the thermocouple
making it necessary to MATCH a gage with
a thermocouple based on wire type (J,K,E,T)
and resistance of the thermocouple lead-wire.
I have installed a C90-12F on my Zenith CH750 project and want to hook up at least one CHT sensor until I can confirm nominal temps within the experimental cowl that is provided. And I don’t want to spend hundreds of bucks if not necessary.
A local acft used parts shop has a couple of used CHT gauges available at very reasonable prices but without sensors and wiring.
Acft Spruce provides a sensor CP131 CHT Probe 18m, part number 10-01440. This sensor will fit under one of my selected cylinder spark plugs.
Would such a sensor work properly with a used CHT gauge? The used gauge I have in mind reads to 600 F and has two leads which I assume connect to the appropriate two leads from the sensor.
The Aircraft Spruce catalog speaks to the use of type E
thermocouple wire on their spark plug gasket offering.
Here are excerpts from the data tables on the three popular
thermocouple types.
Type E
[img]cid:7.1.0.9.0.20161031124007.0216e880(at)aeroelectric.com.0[/img]
Tyoe J
[img]cid:7.1.0.9.0.20161031124007.0216e880(at)aeroelectric.com.1[/img]
Type K
[img]cid:7.1.0.9.0.20161031124007.0216e880(at)aeroelectric.com.2[/img]
As you can see, type E has a lot more output
that J and K. The tough nut is that any gage
used with this particular produce must be
MATCHED to the wire.
The answer to your question is bounded by two
points: (1) match gage to type of thermocouple
wire and (2) finding an 18mm spark-plug gasket
fitted wire appropriate to the gage.
Bob . . .
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
| Description: |
|
| Filesize: |
14.29 KB |
| Viewed: |
4626 Time(s) |
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| Description: |
|
| Filesize: |
14.48 KB |
| Viewed: |
4626 Time(s) |
|
| Description: |
|
| Filesize: |
14.15 KB |
| Viewed: |
4626 Time(s) |
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