Patrick Duffy wrote:

> The greater the exposure to oxygen, the shorter the life of the sensor.
> In the past, I wrapped one sensor in plastic wrap and another I placed
> in a small container where the sensor barely fit.  With the plastic wrap
> (Saran Wrap or similar) I was able to essentially have no air space.
> Both sensors were used to measure the same gas during that period.  In
> the end, the sensor I wrapped in Saran wrap did last a couple months (I
> think it was 4 months) longer than the other.  However, I should note,
> any type of plastic wrap will still allow O2 through the material.
> The sensors arrive in a bag that is thick enough to prevent gas from
> entering, the typical zip lock bags are not thick enough to prevent it.

Seems like I was on the right track but may not have gone far enough to
actually improve the life of my sensor unit.  I think, however, I have.  The
last couple of times I used it, I made a point of checking the reading on my
analyzer before and after I took it from the bag.  The reading has
consistently been lower in the bag than out, suggesting that the sensor has
used up some O2 that has not been replaced.  If I were real serious about
this, I suppose a bit of electrical tape over the small inlet and outlet
would do an even better job.  In the long run, however,it may all be for
nothing.  On the O2 stick, the battery and sensor are supposed to be good
for about the same period.  Since there's no way to turn the battery off,
extending the sensor life may be a waste of time.

> You should know that if the sensors are sealed (as they are from the
> factory), the wake up over a period of hours.  Depending on how long
> they were in the bag, it can take anywhere from 4 to 24 hours for the
> sensor to "wake up" completely.  So, my suggestion is, if you even wrap
> the sensor in some type of plastic wrap, expose it to open air for at
> least 4 hours.  Any sensor opened out of a factory sealed bag should not
> be used for 24 hours (usually levels out at 6 hours).  If you do not,
> your gas measurement MAY NOT be accurate.

Sounds like good advice.  It's also news to me.  Thanks for sharing it Mike.

Lee