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How about air impurity in the carrier gas?

Good luck,
Henry

Ute på vift

> 8 dec. 2018 kl. 02:37 skrev Patrick Griffin <[log in to unmask]>:
> 
> My first reaction is an air leak somewhere upstream from the TC that is degrading the graphitization.   I'm sure you see why that would fit, and so you have troubleshot around it with He sniffer and Ar overpressure on every conceivable fitting.  The second is the magnet current regulator, which I know nothing about in the V but is straightforward to diagnose on the software side.  The other explanations are harder to pin down... shitty for you, fun for us puzzles obsessives.
> 
> How closely have you monitored the high temperature conversion device?  My imagination has concocted a elaborate scenario where everything you've seen matches a nearly-but-not-quite dead heating element with a hairline fracture somewhere. That could either be the wise and helpful voice of experience or the bitterness and resentment of someone who has PTSD from a silicon carbide heating element (Roxanne, Seth, Marilyn?).    I don't know about your device at all, but if you crack it open and find a variable resistor, it may be worthwhile to move it up a step.  If you find the time to fully power down (unplug!) your device, checking the resistance along the element when cold will be definitive.  
> 
> An overnight trace of standard gas that bypasses the thermal conversion can rule out the magnet current regulator.  I would also monitor the injection volume as a function of intensity and d2H since conversion efficiency is dependent on temperature and bond strength is a function of redox conditions.  
> 
> If conditioning returns the B4 standard to good values and good peak heights,  consider overloading your injections with a fast-eluting compound that conditions the reactor on each run.  Works a charm for me.
> 
> Keep us updated.
> 
> -patrick
>