[AR] Re: Best Practices for Measuring Engine Temps with a Thermocouple
- From: Charles Pooley <ckpooley@xxxxxxxxxxxxx>
- To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
- Date: Wed, 16 Oct 2013 17:16:30 -0700 (PDT)
Welding to the engine is best, because the signal from a TC is from the
temperature gradient from the junction to where you measure it. Thin wire
helps.
Then, use an instrumentation amplifier. They measure true differential
voltage. The ground reference for the signals can be the metal surface being
measured. The output is differential also, with a reference voltage for the
output. There are a number of inexpensive ones in 8 pin packages to choose
from. Charles Pooley
________________________________
From: David W. Schultz <david.schultz@xxxxxxxxxxxxx>
To: arocket@xxxxxxxxxxxxx
Sent: Wednesday, October 16, 2013 4:49 PM
Subject: [AR] Re: Best Practices for Measuring Engine Temps with a Thermocouple
On 10/16/2013 06:25 PM, Graham Sortino wrote:
> I’ve been testing out some thermocouples on my revised test stand and I
> was wondering if there is a best practice for connecting the
> thermocouple to the object** being measured?
The best way is to spot weld each thermocouple wire to the metal object.
> touched the tip of the thermocouple wire to my piece of metal.
By doing this you have created an interesting thermodynamics problem.
The wire is at a lower temperature and it begins to heat up when you
touch it to the metal. The tip is pulling heat from the metal but the
wire is cooling the tip. You are also cooling the metal but hopefully
that is a small effect. It seems unlikely that this would ever give a
good result.
--
David W. Schultz
http://home.earthlink.net/~david.schultz
Returned for Regrooving
Other related posts:
