Hi Bob -
I was curious about this so I asked NGK about and they said the
maximum rated pressure for the CM-6 plugs is 250psi. I don't recall
the exact pressure I was testing these too but it was most likely
above 250 psi, which would explain the leaking. I usually run my
igniter at about 100psia and my main engine at 150psia so I will try
to be more careful about this going forward.
Thanks again for the advice.
Best,
Graham
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*From:* Robert Watzlavick <rocket@xxxxxxxxxxxxxx>
*To:* arocket@xxxxxxxxxxxxx
*Sent:* Tuesday, November 4, 2014 9:38 PM
*Subject:* [AR] Re: Igniter Popping Sound
I haven't noticed any leakage around the spark plug after hot firings,
but that's assuming you would see some soot or something if it
leaked. Hot chamber gases coming out the top of the igniter would
definitely be bad.
-Bob
On 11/04/2014 07:25 AM, Graham Sortino (Redacted sender
gnsortino@xxxxxxxxx <mailto:gnsortino@xxxxxxxxx> for DMARC) wrote:
Thanks very much. I'm really happy with the improvement. Also, thanks
too for all of the advice and suggestions.
Regarding erosion... I noticed a little bit of brown color
(presumably rust/oxidization) on the tip ofspark plug tap.
One other thing I noticed is that when pressure testing the igniter
chamber I noticed that the ME-8 plugs leaked a bit when the pressure
was over about 100psia. The leak seems not to be at the thread/seal
but instead at the external part of the plug where the cermaic
portion is mated with the metal bit. I'm probably using the wrong
spark plug terminology here so apologies if this is confusing. I will
try and take a closer look at it tonight and provide a bit more feedback.
On Monday, November 3, 2014 11:30 PM, Robert Watzlavick
<rocket@xxxxxxxxxxxxxx> <mailto:rocket@xxxxxxxxxxxxxx> wrote:
Very nice! The new an improved version looks very stable and has a
nice plume that should light your main chamber just fine. One thing
I wanted to ask you - have you seen any erosion on the spark plug?
I went through several of the little ME-8 plugs while getting it all
worked out. How well did the pressure transducer line hold up?
-Bob
