calibration test gas mixtures [was Re: NTK UEGO calibration]

[David Hunt]

Are these mixtures by mole, weight or volume?

dh
----- Original Message -----
From: "Jason Haines" <jhaines15 at home.com>
To: <diy_efi at diy-efi.org>
Sent: Wednesday, August 22, 2001 10:34 PM
Subject: calibration test gas mixtures [was Re: NTK UEGO calibration]


> As promised, here are some sample gas mixtures for different air fuel
> ratios. These gas mixtures were provided to us by Horiba for use with our
> wide band meters at work but they should apply to any wide band meter. The
> bubbler is a device (looks like a bong) that is designed to add water
vapor
> to the mixture to more closely simulate the gas mixture that would be
> encountered by an O2 sensor (with water being a natural byproduct of
> gasoline combustion). You can do this without the bubbler, you just loose
a
> little bit of accuracy.
>
> With bubbler:
>
> The gas mixture you want for 0.85 lambda (12.5:1 AFR) is:
>  Carbon monoxide 3.4%
>  Hydrogen  2.0%
>  Carbon dioxide 10.0%
>  Nitrogen  balance
>
> The gas mixture you want for .8 lambda (11.76:1 AFR) is:
>  Carbon monoxide 6.64%
>  Hydrogen  2.57%
>  Carbon dioxide 10.0%
>  Nitrogen  balance
>
> A gas mixture for 1.0 lambda (14.7:1 AFR) is:
>  Carbon dioxide 13.0%
>  Nitrogen  balance
>
> A gas mixture of 13.0 AFR:
>  Carbon monoxide 4.1%
>  Hydrogen  0.75%
>  Carbon dioxide 10.0%
>  Nitrogen  balance
>
>
> Without bubbler:
>
> A gas mixture of 13.0 AFR:
>  Carbon monoxide 4.0%
>  Hydrogen  0.733%
>  Carbon dioxide 10.0%
>  Nitrogen  balance
>
> I don't have a lean (>1.0 lambda) gas mixture specification yet. If you
need
> one you can use atmospheric as roughly 20.6 - 20.9% 02. I assume you could
> also use a known 02 % concentration gas (with remainder being something
> semi-inert like nitrogen).
>
> You will want to flow the gas past the sensor(s) at roughly 2-3 liters per
> minute. You do not want to have any back pressure on the system when
> calibrating the sensors (although it would be interested to see how the
> results changed).
>
> These mixtures assume normal gasoline. I don't know how much error not
> having the moisture content or the correct fuel specifications will cause.
> If you look at the difference between the mixtures for the 13:1 AFR with
and
> without the bubbler, you can see the level of accuracy that is being
> targeted here. The difference between 4.1% and 4.0% for the CO and 0.75%
and
> 0.733% for the Hydrogen. =
>
> You will want to get a +/- 1% certified blend but you shouldn't have to
pay
> for an EPA certified blend (you don't need that level of accuracy or
> paperwork). One source for the gas mixtures is Scott Specialty Gases
> (215-766-8861) - they have offices all over the country. Our tank came
from
> Praxair (440-237-8770). I think they also have offices all around the US.
> You can get large tanks like those used for welding gases or you can get
> disposable cylinders but you pay a lot for the disposable cylinders
because
> they normally make the larger cylinder in the custom blend and then fill
the
> disposables from that so you pay for the extra gas anyway.
>
> I hope this if of use to some people.
>
>
> Jason
>
>
>
>
> >
> > > Heater in the WB sensor *will* ignite a propane or butane mix w/ air -
> > > detonate is more like it.  Did that.
> > >
> > > I'm just a minor in chem from 40 years ago, so its a bit
misty....really
> > > dunno how these things work.
> > >
> > > I used argon/CO2 MIG mix to get stoich; ran a couple of WBs, compared
to
> > > the switching of a NB sensor.  Used a 1 qt Mason jar w/ holes in the
lid
> > > for the sensors & small hole to admit gasses.  Convection from the
> > > heater(s) mixes things well, adding a very small muffin fan didn't
> change
> > > anything.  Starting w/ air in the jar (offscale lean), running argon
in,
> > > AFRs fall to 14.7:1.  Adding propane or butane at this point is safe,
> but
> > > doesn't take much to *really* swing the AFR rich.  Far as I can tell,
> *no*
> > > O2 and *no* hydrocarbon = stoich - add either O2 or hydrocarbon gas to
> get
> > > the full range of AFRs.
> > >
> > > Short of a bomb deal, I couldn't come up w/ a reproducable means of
> mixing
> > > known amounts of gasses & come up w/ a 'cal' gas.  These are available
> > > commercially, mostly for EPA stuff & come w/ all sorts of assays &
> > > certificates w/ a price tag to match - try BOP gasses.
> > >
> > > Barry
> > >
> > > At 04:39 PM 8/21/01 -0400, you wrote:
> > > >For those of us that are not chemists, is there a cheap way that is
> > > >also safe (not that I don't like to blow things up as long as I am
not
> > > >one of those things).
> > > >
> > > >What about Propane?  Or Butane?  Something readily available, and if
> > > >so how would one go about testing?  Will the heater in the O2 sensor
> > > >start an explosion with Propane or other?
> > > >
> > > >Where would one get nitrogen or argon?  Is there an easy way to make
> > these
> > > >gases (that is also safe)?
> > > >
> > > >Thanks,
> > > >
> > > >Steve F
> > > >
> > > >-----Original Message-----
> > >
> >
>
> --------------------------------------------------------------------------
> > --
> > > To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the
> > quotes)
> > > in the body of a message (not the subject) to
> majordomo at lists.diy-efi.org
> > >
> > >
> >
>
> --------------------------------------------------------------------------
> --
> > To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the
> quotes)
> > in the body of a message (not the subject) to
majordomo at lists.diy-efi.org
> >
>
> --------------------------------------------------------------------------
--
> To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the
quotes)
> in the body of a message (not the subject) to majordomo at lists.diy-efi.org
>
>


----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org