Re: [xj-s] Valve seats & LN2

["Craig Sawyers" <craig@sawyers.demon.co.uk>]

The other way is to use an expanded polystyrene jug.  These are purchasable
quite easily and don't have the problems of explosion and glass shards.

Craig Sawyers
-----Original Message-----
From: John_Warr-1@sbphrd.com <John_Warr-1@sbphrd.com>
To: xj-s@jag-lovers.org <xj-s@jag-lovers.org>
Date: 02 July 1998 08:40
Subject: [xj-s] Valve seats & LN2


>
>
>
>
>To:       xj-s@jag-lovers.org
>cc:
>From:     John Warr-1 @ SB_PHARM_RD
>Date:     02-Jul-98 08:39:32 AM
>Subject:  Valve seats & LN2
>Categories:
>
>John Napoli wrote
>
>>Go to your local dermatologist and fill up your thermos bottle with
>>liquid nitrogen.  It will last for hours if not days.
>
>Whilst I don't usually issue safety warnings, on the principal that
>evolution
>has worked pretty well so far, so why mess with a good system, I would
>just say this. The principal is sound, but WATCH THAT THERMOS.
>
>1.
>This may sound obvious, but DON'T PUT THE TOP ON.
>
>Just use a loose fitting polystyrene bung to keep out enquiring pussycats
>(and cut down on evaporation caused by drafts). If you seal the top at all,
>the pressure build up will blow the thing to buggery.
>
>2.
>Food type thermos flasks are not really designed for use with cryogens.
>This can result in hairline cracks. Liquid nitrogen is then pulled into the
>vacuum cavity, and the insulation breaks down. This in turn causes the LN2
>to
>boil away fairly rapidly. At this point, we* are left with the nitrogen
>which
>was pulled into the vacuum space. When this boils, it has nowhere to go.
>
>Kaboom
>
>It is like a 12 gauge cartridge exploding in your hand, accompanied by huge
>amounts of glass shrapnel. If you don't have a cryogen flask handy, use a
>stainless steel jobbie. The LN2 won't last quite as long, but your eyesight
>and
>boyish good looks will be preserved.
>
>3.
>Take off rings & similar. LN2 is pretty safe UNTIL it is trapped against
>the skin.
>You were going to do that anyway, weren't you ?
>
>
>Y'rs &c
>
>John Warr
>
>*.....not actually we. At this point, I have legged it, and you are on your
>own.
>
>
>
>

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