Oil filled gauge and O2

I will be replacing a gauge soon. It's used for
Nitrox and Trimix blending. Is there any reason
why I shouldn't use an oil filled gauge with O2?

Steve Chaplin wrote:
> I will be replacing a gauge soon. It's used for
> Nitrox and Trimix blending. Is there any reason
> why I shouldn't use an oil filled gauge with O2?

Since the oil is outside the bourden tube I can't see why not.
If it leaked it would not be HP O2 just one bar which is pretty
safe stuff.

I bought a digital for blending. I know the cell might not be
any more accurate than I could read a pointer but all those
decimals look soooo sexy.

nigelH

You said the following on 02/22/04 03:56:
> Since the oil is outside the bourden tube I can't see why not.
> If it leaked it would not be HP O2 just one bar which is pretty
> safe stuff.
This is my thinking. People who I believe should know better
seem to think you need a dry gauge for O2. I just wanted to
check I was not missing something obvious.

> I bought a digital for blending. I know the cell might not be
> any more accurate than I could read a pointer but all those
> decimals look soooo sexy.
Those on the price tag a little less so!

S
--
----------------------------------------------------------
Steve Chaplin
usenet5@codekey.co.uk

On Sun, 22 Feb 2004 03:56:13 +0000 (UTC), "Nigel Hewitt"
<nigelh@REMOVETHISnigelhewitt.net> wrote:

>If it leaked it would not be HP O2 just one bar which is pretty
>safe stuff.

How did you work that one? Lets say I've got 32% @ 230 bar that's 73
bar

Pete
diving 'at' melbourne 'dot' me 'dot' uk

Pete Melbourne wrote:
> "Nigel Hewitt" wrote:
>
>> If it leaked it would not be HP O2 just one bar which is pretty
>> safe stuff.
>
> How did you work that one? Lets say I've got 32% @ 230 bar that's 73
> bar

The oil is outside the tube.
Outside the tube is one bar.
Otherwize it wouldn't work.

Knowing what the cases on oil filled gauges are like
half a bar over pressure and you'll be cleaning the
oil off the walls. The last one I saw was made of brass
'plate' you might have thought was a bit thick and a
funny colour if you bought it as cooking foil but not
by much. The oil is there to prevent the case crumpling
compeletely at depth while still allowing you to keep
water out of the gears and other works.

nigelH

On Mon, 23 Feb 2004 15:06:14 GMT, "Nigel Hewitt"
<news@REMOVETHISnigelhewitt.net> wrote:

>Pete Melbourne wrote:
>> "Nigel Hewitt" wrote:
>>
>>> If it leaked it would not be HP O2 just one bar which is pretty
>>> safe stuff.
>>
>> How did you work that one? Lets say I've got 32% @ 230 bar that's 73
>> bar
>
>The oil is outside the tube.
>Outside the tube is one bar.
>Otherwize it wouldn't work.
>
>Knowing what the cases on oil filled gauges are like
>half a bar over pressure and you'll be cleaning the
>oil off the walls. The last one I saw was made of brass
>'plate' you might have thought was a bit thick and a
>funny colour if you bought it as cooking foil but not
>by much. The oil is there to prevent the case crumpling
>compeletely at depth while still allowing you to keep
>water out of the gears and other works.
>

But if you get a leak then surely that leak will be at tank pressure?

Pete
diving 'at' melbourne 'dot' me 'dot' uk

Pete Melbourne wrote:
> But if you get a leak then surely that leak will be at tank pressure?

But I can't see how the oil can ever get to any significant pressure.
The case will rupture and you might get a sudden flash as it burns
but it is not contained at pressure as in an oxygen fire inside a
contaminated pump. Then there is a real risk of igniting the metal.
If you've done acetylene cutting you know that is something to watch.
The oil does not add anything significant to the 'risk assessment'
of the gauge.

At one bar oxygen goes from highly dangerous to just simple
nasty. Yes, there used to some horrific accidents when some old
man in an oxygen tent borrowed a fag off one of his mates (what
Matron doesn't see won't hurt me). It burnt fast, scorched his
fingers and he dropped it so the bedding went up in flames.
Emphysema to terminal burns in 0.1 seconds. I think that's why
they only use masks in hospital now, to protect the patients from
their visitors.

nigelH