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Subject: Re: Furnace oil tank safety alarm
X-Newsreader: Microsoft Outlook Express 5.50.4807.1700
Date: Sun, 8 Sep 2002 11:34:08 -0400
NNTP-Posting-Date: Sun, 08 Sep 2002 11:23:24 EDT
Organization: Bell Sympatico
"Paul Honigmann" wrote in message
> gagir writes
> >So you would measure evaporated CH compounds?
> Yes. You can use infrared (spectroscopy) tuned to C-H bonds, or
> pellistor techniques which react to any vapour which burns. Or
> semiconductor sensors, but personally I don't like those much because
> they react to anything, including ambient temperature and humidity
> changes, so you don't know if it's a real alarm or not.
> >The sensitivity has to be way up there for it to react at the begining of
> >small leak, but still be able to discriminate other small gas leaks such
> >humans dispensing methane...;P
> Those will get diluted to parts per billion 8)
Well you haven't been to our family gatherings @(
> Infrared will show up ppm and pellistors (which are rather old fashioned
> but cheap, and they work) will show up levels of around 0.05%. Since the
> flammable level of most gases is around 1 to 5% by volume in air, the
> obvious choice would be to use a cheap pellistor.
The problem here is less flamability than clean up costs.
> The catch is that such a system is going to set you back... I dunno... a
> couple of thousand Euros I guess. Because it needs to trigger an alarm
> somewhere, so you need a PLC, etc etc. All the bits add up. An amateur
> could knock something together much cheaper, but the professional
> companies need to recover costs spent proving these things are safe. You
> aren't allowed to sell equipment for hazardous areas (where there is
> potentially flammable vapour) without third party testing and stuff and
> it's all very expensive.
My job is to do electronics and instrumentation in the photonics business.
We use 5K psi H2, so I know what you mean.
> Come to think of it, we recently developed something called "FlamSafe"
> which is a cut price system specifically for this kind of application,
> so you might want to check that on the URL below.
Could not find this product, I will use the product enquiry form.
> Gosh this Sales stuff is hard. I'd better stick to engineering. You
> don't need communication skills for that.
Well then, I will understand what I need from you and buy elswhere ; ~)
> >> I'd just like to point out that the company I work for makes leak
> >> detector type things* for flammable gases - check out www.crowcon.com
> >> --
> >> Paul Honigmann
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