[PSUBS-MAILIST] O2 gauge

Wed Nov 26 15:04:05 EST 2014

We have a Crowcon Tetra 3 which does O2, Co and CO2.  It also does H2 but not to scale  Registers as CO.  i.e. it goes off with lead acid battery charging.  Was not cheap and needs “Calibration” every year and tells you so.

We have accessed the internals via computer to download and use its data sourcing to control the Oxy input solenoid.

Crowcon say it cant be done but we have done it anyway.  Since found out that you can get the same beast thru BOC for half the price!

Hugh 

From: Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org] On Behalf Of Alec Smyth via Personal_Submersibles
Sent: Thursday, 27 November 2014 4:01 a.m.
To: Personal Submersibles General Discussion
Subject: Re: [PSUBS-MAILIST] O2 gauge

Hi Hank,

I'm on my third. The first two came as a pair in an eBay auction, which was ideal because that way I had a spare. I sure needed it, because the first one lasted 15 minutes in the heat and humidity of a Florida dive. They seemed like ideal units; brand name, back-lit display, high and low visual and audible alarms. The second lasted a bit longer, maybe a season. Then I cobbled together a working one by combining parts from the two and got one more season out of that. It was instructive taking these things apart. After just a few dives the printed circuit boards looked like the terminals on an old car battery, all covered in whitish gunk, and its not like I dropped them over the side. My take-away was to avoid instruments that are intended for a hospital. Go instead for something intended for the field (sealed, clip-on, small enough to go in your pocket, etc.) The hospital units work perfectly in the garage but die very soon after you start using them on actual dives.

My current one you can find on eBay by searching "SPD201". It has the benefit of being really cheap. It is not as ruggedly encased as more expensive field units, but it has managed to survive several seasons without turning into a battery terminal, so I'd rate the quality as "not the best but good enough". There are two things I'd change about it, but they're both minor. First, it has two alarms but they are both low alarms and for our application it would be better to have one high and one low alarm. Second, the backlight comes on when you press a button but turns itself off after a while to conserve the battery - I'd rather it stayed on until switched off again.   

Best,

Alec

On Tue, Nov 25, 2014 at 3:20 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Hi all,
Can you guys tell me what type of O2 monitoring device your using and do you recommend it.
Thank you
Hank
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