Today's Message Index:
----------------------
1. 07:47 AM - Re: Thermocouple compatible bulkhead connector? (Noel Loveys)
2. 08:07 AM - Re: Thermocouple compatible bulkhead connector? (Ron Quillin)
3. 08:37 AM - Re: Thermocouple compatible bulkhead connector? (Kevin Carey)
4. 10:50 AM - Re: Thermocouple compatible bulkhead connector? (John Loram)
5. 10:55 AM - Re: Thermocouple compatible bulkhead connector? (John Loram)
6. 11:57 AM - Re: Thermocouple compatible bulkhead connector? (rampil)
7. 11:59 AM - Re: Thermocouple compatible bulkhead connector? (Noel Loveys)
8. 01:29 PM - Re: Thermocouple compatible bulkhead connector? ()
Message 1
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| Subject: | Thermocouple compatible bulkhead connector? |
John:
My advice would be to just use a grummet. The wires on thermocouples have
to be a consistent types of metal from the couple itself to the instrument.
Finding a multi pin bulkhead fitting in the exact correct metals may be
difficult if not impossible.
If your plane is certified be sure to follow AC43 for specs on cable
supporting.
Noel
-----Original Message-----
From: owner-avionics-list-server@matronics.com
[mailto:owner-avionics-list-server@matronics.com] On Behalf Of John Loram
Sent: February 3, 2010 7:33 PM
Subject: Avionics-List: Thermocouple compatible bulkhead connector?
Does any one know of a source (other than Omega) for multi-pin bulkhead
connectors that are compatible with Type J & K thermocouples? I wiring the
firewall foreword...
thanks, -john-
Message 2
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| Subject: | Thermocouple compatible bulkhead connector? |
At 07:47 2/5/2010, you wrote:
>The wires on thermocouples have
>to be a consistent types of metal from the couple itself to the instrument.
I don't believe as stated that's entirely true.
A voltage is developed across a junction of differing metals, that's
why a TC works, but...
If a transition is made from conductor metal type A, to conductor
metal type B, we'll assume some voltage +E is developed. However,
when transitioning back from conductor metal type B to conductor
metal type A, voltage E is again developed, but it is now -E. When
both transitions are at the same temperature, the voltages cancel one
another out and minimal if any error voltage is generated.
We do this all the time in a thermal-vacuum chamber used for NASA
satellite/spacecraft verification all the time and it's quite
acceptable; assuming the transitions are at a constant or nearly so
temperature. While the instrument within the chamber is cycled from
~ +85C to ~ -100C, the transition connector remains near ambient ~
+22C. Errors are minimal and well within acceptable limits.
Ron Q.
Message 3
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| Subject: | Re: Thermocouple compatible bulkhead connector? |
Have you checked with the manufacturer of the EGT/CHT system you're using?
I have an EI UBG-16 and when I checked with EI, they didn't have a problem
with using a standard multi-pin connector at the bulkhead. There are
already two pretty common looking multi-pin connectors in the harness for
the EGT and CHT leads installed at the factory.
Kevin
----- Original Message -----
From: "Noel Loveys" <noelloveys@yahoo.ca>
Sent: Friday, February 05, 2010 10:47 AM
Subject: RE: Avionics-List: Thermocouple compatible bulkhead connector?
>
> John:
>
> My advice would be to just use a grummet. The wires on thermocouples have
> to be a consistent types of metal from the couple itself to the
> instrument.
> Finding a multi pin bulkhead fitting in the exact correct metals may be
> difficult if not impossible.
>
> If your plane is certified be sure to follow AC43 for specs on cable
> supporting.
>
> Noel
>
> -----Original Message-----
> From: owner-avionics-list-server@matronics.com
> [mailto:owner-avionics-list-server@matronics.com] On Behalf Of John Loram
> Sent: February 3, 2010 7:33 PM
> To: avionics-list@matronics.com
> Subject: Avionics-List: Thermocouple compatible bulkhead connector?
>
>
> Does any one know of a source (other than Omega) for multi-pin bulkhead
> connectors that are compatible with Type J & K thermocouples? I wiring the
> firewall foreword...
>
> thanks, -john-
>
>
>
Message 4
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| Subject: | Thermocouple compatible bulkhead connector? |
You're quite correct Ron. Somehow I had failed to notice that I would be
creating two, opposite polarity junctions that would be "isothermal"...
Now, I just need to find a cheap source for mil spec circular connectors
(MIL-C-5015). Anybody have a favorite source? I need a bulkhead and plug
connector with 24 pins for the thermocouples.
thanks all for comments, -john-
_____
From: owner-avionics-list-server@matronics.com
[mailto:owner-avionics-list-server@matronics.com] On Behalf Of Ron Quillin
Sent: Friday, February 05, 2010 8:07 AM
Subject: RE: Avionics-List: Thermocouple compatible bulkhead connector?
At 07:47 2/5/2010, you wrote:
The wires on thermocouples have
to be a consistent types of metal from the couple itself to the instrument.
I don't believe as stated that's entirely true.
A voltage is developed across a junction of differing metals, that's why a
TC works, but...
If a transition is made from conductor metal type A, to conductor metal type
B, we'll assume some voltage +E is developed. However, when transitioning
back from conductor metal type B to conductor metal type A, voltage E is
again developed, but it is now -E. When both transitions are at the same
temperature, the voltages cancel one another out and minimal if any error
voltage is generated.
We do this all the time in a thermal-vacuum chamber used for NASA
satellite/spacecraft verification all the time and it's quite acceptable;
assuming the transitions are at a constant or nearly so temperature. While
the instrument within the chamber is cycled from ~ +85C to ~ -100C, the
transition connector remains near ambient ~ +22C. Errors are minimal and
well within acceptable limits.
Ron Q.
Message 5
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| Subject: | Thermocouple compatible bulkhead connector? |
Turns out that such connectors do exist in several different version. You
buy the pins separately to match the thermocouple wire. Pins cost about $20
each. However, I've finally realized that it won't be necessary to use a
special connector. (see other posts on same subject).
I'm determined not to have to disconnect 24 wires for thermocouples every
time I want to pull the engine.
-john-
> -----Original Message-----
> From: owner-avionics-list-server@matronics.com
> [mailto:owner-avionics-list-server@matronics.com] On Behalf
> Of Noel Loveys
> Sent: Friday, February 05, 2010 7:47 AM
> To: avionics-list@matronics.com
> Subject: RE: Avionics-List: Thermocouple compatible bulkhead
> connector?
>
> <noelloveys@yahoo.ca>
>
> John:
>
> My advice would be to just use a grummet. The wires on
> thermocouples have to be a consistent types of metal from the
> couple itself to the instrument.
> Finding a multi pin bulkhead fitting in the exact correct
> metals may be difficult if not impossible.
>
> If your plane is certified be sure to follow AC43 for specs
> on cable supporting.
>
> Noel
>
> -----Original Message-----
> From: owner-avionics-list-server@matronics.com
> [mailto:owner-avionics-list-server@matronics.com] On Behalf
> Of John Loram
> Sent: February 3, 2010 7:33 PM
> To: avionics-list@matronics.com
> Subject: Avionics-List: Thermocouple compatible bulkhead connector?
>
>
> Does any one know of a source (other than Omega) for
> multi-pin bulkhead connectors that are compatible with Type J
> & K thermocouples? I wiring the firewall foreword...
>
> thanks, -john-
>
>
>
>
>
>
>
> Photoshare, and much much more:
>
>
>
>
Message 6
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| Subject: | Re: Thermocouple compatible bulkhead connector? |
Amphenol certainly makes TC compatible pins for J & K combos.
You might be able to request samples. These pins are usually not
stocked at Digikey or Newark, etc, but that does not mean they are
not potentially available. Check the Amphenol catalogs for your choice
in metal or plastic circular connectors.
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=284991#284991
Message 7
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| Subject: | Thermocouple compatible bulkhead connector? |
As far as i know for certification the metals have to be consistant... If
the plane is not certified that is not a requirement.
Noel
From: owner-avionics-list-server@matronics.com
[mailto:owner-avionics-list-server@matronics.com] On Behalf Of Ron Quillin
Sent: February 5, 2010 12:37 PM
Subject: RE: Avionics-List: Thermocouple compatible bulkhead connector?
At 07:47 2/5/2010, you wrote:
The wires on thermocouples have
to be a consistent types of metal from the couple itself to the instrument.
I don't believe as stated that's entirely true.
A voltage is developed across a junction of differing metals, that's why a
TC works, but...
If a transition is made from conductor metal type A, to conductor metal type
B, we'll assume some voltage +E is developed. However, when transitioning
back from conductor metal type B to conductor metal type A, voltage E is
again developed, but it is now -E. When both transitions are at the same
temperature, the voltages cancel one another out and minimal if any error
voltage is generated.
We do this all the time in a thermal-vacuum chamber used for NASA
satellite/spacecraft verification all the time and it's quite acceptable;
assuming the transitions are at a constant or nearly so temperature. While
the instrument within the chamber is cycled from ~ +85C to ~ -100C, the
transition connector remains near ambient ~ +22C. Errors are minimal and
well within acceptable limits.
Ron Q.
Message 8
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| Subject: | Re: Thermocouple compatible bulkhead connector? |
I've used the 38999 series Mil connectors (with std gold pins) with
great success for all kinds of firewall connections - including K and J
type thermos. Flame Enterprises as a distributor for Mil-everything.
http://www.flamecorp.com/
The CPC Series 2 connectors are also good, but they are plastic - not
recommended for use on the firewall. You can get those from all the
usual suspects - Mouser, Digi-Key, Allied, etc. I have not used them,
but they may come in a metal form factor...dunno.
James Redmon
Berkut #013/Race 13
www.berkut13.com
----- Original Message -----
From: John Loram
To: avionics-list@matronics.com
Sent: Friday, February 05, 2010 10:48 AM
Subject: RE: Avionics-List: Thermocouple compatible bulkhead
connector?
You're quite correct Ron. Somehow I had failed to notice that I would
be creating two, opposite polarity junctions that would be
"isothermal"...
Now, I just need to find a cheap source for mil spec circular
connectors (MIL-C-5015). Anybody have a favorite source? I need a
bulkhead and plug connector with 24 pins for the thermocouples.
thanks all for comments, -john-
-------------------------------------------------------------------------
---
From: owner-avionics-list-server@matronics.com
[mailto:owner-avionics-list-server@matronics.com] On Behalf Of Ron
Quillin
Sent: Friday, February 05, 2010 8:07 AM
To: avionics-list@matronics.com
Subject: RE: Avionics-List: Thermocouple compatible bulkhead
connector?
At 07:47 2/5/2010, you wrote:
The wires on thermocouples have
to be a consistent types of metal from the couple itself to the
instrument.
I don't believe as stated that's entirely true.
A voltage is developed across a junction of differing metals, that's
why a TC works, but...
If a transition is made from conductor metal type A, to conductor
metal type B, we'll assume some voltage +E is developed. However, when
transitioning back from conductor metal type B to conductor metal type
A, voltage E is again developed, but it is now -E. When both
transitions are at the same temperature, the voltages cancel one another
out and minimal if any error voltage is generated.
We do this all the time in a thermal-vacuum chamber used for NASA
satellite/spacecraft verification all the time and it's quite
acceptable; assuming the transitions are at a constant or nearly so
temperature. While the instrument within the chamber is cycled from ~
+85C to ~ -100C, the transition connector remains near ambient ~ +22C.
Errors are minimal and well within acceptable limits.
Ron Q.
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