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Do you trust your temperature probes ?
16-12-2018, 08:05 PM
Post: #1
Tongue Do you trust your temperature probes ?
Thought I'd throw this in as it illustrates how easily things can go wrong. A bit of a long winded lead in, but here goes.

For a few years I have been using my Therma3 probe to monitor the temperature of the oil when making bio. It is an industrial digital unit originally used for probing meat.

Anyway. a few days ago I was wondering about the temperature of the beds in my green house. so I stuck the probe into the ground. 8C. 'That's a bit low' thinks I. So needing to check the probe I cleaned it and put it under my tongue. 26C.

That is pretty close to hypothermia. Was I dying ? Feel ok.

On cross checking with a standard thermometer I found the probe was reading 10 degrees low.

'And where is the relevance to bio ?' you may by thinking by now.

Well, I heat my oil to 50C for processing. That is 50C as indicated on this probe. Which is actually 60C.
Had I been trying for a bit more performance I may have heated the oil to an indicated 55C. An actual 65C which, as we all know, is 1C above the boiling point of Methanol.

Guess I have been lucky.

Dave.
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16-12-2018, 09:16 PM
Post: #2
RE: Do you trust your temperature probes ?
The above is a good point to remember. I have a mercury thermometer that has been checked against an NPL standard unit, this has reminded me to recheck my lower grade temp probes.

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16-12-2018, 11:28 PM
Post: #3
RE: Do you trust your temperature probes ?
Yes, digital probes are great for speed and convenience. But, like most things electronic, not to be trusted blindly.

Dave.
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16-12-2018, 11:45 PM
Post: #4
RE: Do you trust your temperature probes ?
That's a good point about accepting and relying upon assumed calibration.

When meth is mixed with the catalyst, the MeOx can be pushed much higher than 64 C without it boiling off significantly.
With a GL plant, any vapour goes round the loop anyway.
(I think...)

Location: N.E. London.
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17-12-2018, 10:16 PM
Post: #5
RE: Do you trust your temperature probes ?
If I'm pushing the temps a bit it comes out of the condensor, which is a pain!

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