Dear Dave,

Don't get offended! Let me answer your questions first:

1. Yes, I did try to make a point.
   (copying Jeff Bentley's style without success, I must add)
2. Yes, I don't have the Handi but think having 2-digit is fine.
3. All.
4. Yes. Because I built mine. They work fine.

Think about this for a minute... Assuming you want max PO2 of 1.2, 11.5%
would let you go down to 94m (308ft). If you have 12.5%, PPO2 at 94m would
be 1.3

Is it a big deal ? I don't think it is, and it would be even less important
when you mix higher O2% for Nitrox and deco gas.

They were rhetorical questions as I knew the sensor accuracy. All of them
are about 2-3% off *full-scale*. Do you understand what that mean ? :-)

I used to use the voltmeter/calculator method for a long while and it is
fine even now. The only reason I built the meters was the chance to learn
some electronics.

I don't mix even 1/100th of the amount the WKPP guys do, but enough to not
worry about the decimal places on my trimix. If you use a good pressure
gauge and correct fill rate, you shouldn't be surprised when reading your
analyzer.

This reminds me of people who PP blend to the exact single-digit, or deco to
the exact second, or uses Helium analyzer...

I wasn't really trying to pick a fight with you, but now you sound pretty
obnoxious :-)

-Phi

-----Original Message-----
From: David Dalton [mailto:david_dalton@ho*.co*]
Sent: Wednesday, August 16, 2000 3:40 PM
To: phi@sk*.be*; david_dalton@ho*.co*; Bakalite@ba*.co*;
dmdalton@qu*.ne*; Art.Paltz@R2*.CO*; techdiver@aq*.co*;
cavers@cavers.com
Subject: RE: "OMS Like" DIN flow regulator


"Phi Le" wrote:

>Dave,
>
>Assuming this is 2-digit and no decimal places, that should cover the range
>from 00 to 99 for O2.
>
>How accurate do you need your mix to be ? And do you know how accurate your
>sensor is ? :-)
>
>-Phi


Dear Phi,

A few questions and then the answers you asked for:

If I misunderstood your tone/intent my appologies but

Did you have a point you were trying to make?
Do you think the Handi is a suitable unit for all O2 analyzing tasks?
If not all, which ones do you think it is good for?
Do you use one? Why did you decide on it? How has it worked out for you?

Your questions seem to want to start an argument as opposed to seeking
knowledge. 2 minutes on their web site would have told you the acuracy of
the Handi & the MAX 250-E.


The following are the reasons I chose not to use a Handi O2 analyzer:

1 ) In-my-never-to-be-humble-opinion 2 digit display is fine for
recreational nitrox. For a low O2% trimix it might not be. As I am just
starting to mix I would say others (George, JJ, Jess, Scott) on these list
could address the usefulness of this unit in those applications far better
than I, and I defer to them.

2) A 2 digit display could introduce an additional error of as much as 1%
(11.5%-12.5% displayed as 12%, you wanted 11.5%, you tested and got 12% so
you think you are close but you really got 12.5% so you are off by 1.0%
rather than 0.5%).

3) The unit itself is accurate +/- 3% full scale over operational
temperature range (as listed on their site)

4) The MAX 250 E is accurate +/- 2% of full scale (as listed on thier site)

5) Combining 2 & 3 above I would deduce that you are looking at a unit to
unit accuracy level of 2% vs 4%.

6) The Handi cost about $230 with the fittings that started this thread.

7) I just built my own and it cost $136.50 including the sensor + fittings -
Oh, I almost forgot I bought my computer geek a Mountain Dew @ $1.04 to
modify the panel meter for me - at 52 the eyes don't like close work and the
hands are no longer suitable for conducting brain surgery.

8) In 2 to 4 years when my sensor "cashes in it's chips" it will cost me $65
for a new one instead of $200 for a new Handi-dandy (and I hate throwing
away the "car just because it needs new sparkplugs").

9) If I was as cheap as MOST divers, I could have just used my Radio Shack
Digital Multi Meter (which I bought for $39.95 a number of years ago) and a
$5 calculator in concert with the MAX 250. That way my expenditures would
have only been about $95 for the MAX 250 and fittings or $65 if I skipped
the fittings.

Please excuse any errors. I am new to diving, I didn't start until 1962 :-).

Dave Dalton



>
>-----Original Message-----
>From: David Dalton [mailto:david_dalton@ho*.co*]
>Sent: Tuesday, August 15, 2000 5:52 PM
>To: Bakalite@ba*.co*; dmdalton@qu*.ne*; Art.Paltz@R2*.CO*;
>techdiver@aq*.co*; cavers@cavers.com
>Subject: Re: "OMS Like" DIN flow regulator
>
>
>Paul,
>
>I guess I was unclear in what I posted. I wouldn't recommend the Handi
>analyzer, since it's use is limited with only a 2 digit display, but their
>BC adapter and barbed adapter will work with their medical & industrial
>sensors such as the MAX 250E.
>
>Dave
>

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